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习题练习:gc textbook chapter 7 Linear Momentum



 作者: admin   总分: 102分  得分: _____________

答题人: 匿名未登录  开始时间: 24年12月27日 14:40  切换到: 整卷模式

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1#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
We claim that momentum is conserved, yet most mchfj4i6w 7 rbot,kr*4r9d4 x0v t,e qtoving objects eventually slow down and stop. Eb 90k,jht4 wqv f6rrxet,c4i4o *7t rdxplain.
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2#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
When a person jumps from a tree to the ground, what happens totov o;3sdp9b- the momentum of the peb- vo9;t3odsprson upon striking the ground?
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3#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
When you release an inflated but untied balloon, why does it fly across the rxapoq9 oepgv +:p.,t)u1o : rtoom.op q:rtgx pao eu: vopt19,+)?
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4#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
It is said that in ancient times a rict w) c/aweavq s4y1j5*h man with a bag of gold coins froze to death while stranded on a frozen lake. Because the ice was frictionleats1/y)q5a4*jc vw wess, he could not push himself to shore. What could he have done to save himself had he not been so miserly?
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5#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
How can a rocket change direction when it is far out in space and isfn,z/zlj3lr7vi q3n( essentiallyzjf,izl l nnr(3 /37qv in a vacuum?
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6#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
According to Eq. 7–5, the longer the impls i 9*tk jo,x+dl1r6fact time of an impulse, the smaller the force can be for the same momenod+*1 t, ll9x6fsijrktum change, and hence the smaller the deformation of the object on which the force acts. On this basis, explain the value of air bags, which are intended to inflate during an automobile collision and reduce the possibility of fracture or death.
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7#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Cars used to be built as dcnn. eax)h y3bq,0y()fwnsb xmd t 0(-jo-3b rigid as possible to withstand collisions. Today, though, cars are desi(3m-bxd)ncx0 eqfbb-n ja hdo 3ts( wn,0y )y.gned to have “crumple zones” that collapse upon impact. What is the advantage of this new design?
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8#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Why can a batter hit a pitched baseball further than a ball tossed in the air bku d8m v8w:;2 xz)behby the batter? u)bdz:2w8bm8 hek;vx
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9#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Is it possible for an object to receive a larger impulse from a smast * xm,wvc)4r-olhm du.16okll force than foo6lh1v.x * )du4kwtmms ,c-rrom a large force? Explain.
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10#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A light object and a heavy object have the same kinetic. ;tjkazu6rrb 2+wpp0 energy. Which has the greater momentu ;6pp.au 0rjtkb rz+2wm? Explain.
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11#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Describe a collision in which all kineti: z6vb.(yw, qi f/z6yst+wcov c energy is lost.
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12#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
At a hydroelectric power plant, water is directed at brkzuhb1u (* 0high speed against turbine uh0ur bk(bz *1blades on an axle that turns an electric generator. For maximum power generation, should the turbine blades be designed so that the water is brought to a dead stop, or so that the water rebounds?
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13#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A squash ball hits a o06q -jya9e ueed+a*m wall at a 45 $^{\circ} $ angle as shown in Fig. below. What is the direction (a) of the change in momentum of the ball, (b) of the force on the wall?
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14#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A Superball is dropped from a height h onto a hard steel plate (fixed to thldya blhjo +1 l *,8lowr.xy6*e Earth), from which it rebounds at very nearxlo8*a*olh yy. ,r6+l bd1wljly its original speed. (a) Is the momentum of the ball conserved during any part of this process? (b) If we consider the ball and Earth as our system, during what parts of the process is momentum conserved? (c) Answer part (b) for a piece of putty that falls and sticks to the steel plate.
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15#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Why do you tend to lean backward whendr r . zbgmvw;q3*.bv+ carrying a heavy load in your arms?
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16#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Why is the CM of a 1-m length of pipe at its m (ho4x.hno6i mid-point, whereas this is not true for yo6nox(h hmo4.iur arm or leg?
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17#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Show on a diagram how your CM sh/awy2c57oo+y f 8plhb ifts when you change from a lying position to a sitting positionp/ 8abyho25+cw 7lyf o.
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18#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
If only an external force can change the momentum of the center of j cb(3pwpj7:7yq b,*sxl1 o ihmass of an objecbxpi3qjc:bpoj lsw7 1 7hy (*,t, how can the internal force of an engine accelerate a car?
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19#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A rocket following a parabolic path through the air suddenly explodes -r4forvia:b) . ghd. soph 2y)into many pieces. What can yoh.:ry g ))bpfdvo2r.ia- sh4ou say about the motion of this system of pieces?
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20#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the magnitude of the momentum of a 28-g sparrow flying with a speed o0m 3ijdg * tgvvp//-+qzg m4vaf $8.4 \; m/s$    $kg \; m/s$

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21#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A constant friction force of 25 N acts on a 65-kg skier for 20 s. Wh1xz;f2g8 e-nnkuj/0 papkay( c b1mn6at is the skier’s cec ayn8 0k/p ;n-ngj1xb( p 21amkzu6fhange in velocity?    m/s

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22#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 0.145-kg baseball pitched at 8qxmj dqwbzs2 9g.+f9 39 m/s is hit on a horizontal line drive straight bac2wsgzq xdb8+fm9 . j9qk toward the pitcher at 52m/s If the contact time between bat and ball is $3\times10^{-3}$s calculate the average force between the ball and bat during contact.    N

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23#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A child in a boat throws a 6.40-kg package out horizontally with a speed of 1l x:e70;gvq/xn-v zv s0 m/s Fig. below Calculate the velocity of the v v/-nz 7;g: 0lvxseqxboat immediately after, assuming it was initially at rest. The mass of the child is 26.0 kg, and that of the boat is 45.0 kg. Ignore water resistance. The magnitude of the velocity of the boat is    m/s


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24#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the force exerted on a rocke.6t)3hd lh(yeac2u c lt, given that the propelling gases are expelled at .hcu3 ldl6t )(he2ayca rate of $1500 \; kg/s$ with a speed of $ 4\times10^{4 } \; m/s$ (at the moment of takeoff). F =    $\times 10^7 \; N$

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25#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 95-kg halfback moviyltn:-4 gaczkyt;42:sl rhp ;ng at $4.1 \; m/s$ on an apparent breakaway for a touchdown is tackled from behind. When he was tackled by an 85-kg cornerback running at $5.5 \; m/s$ in the same direction, what was their mutual speed immediately after the tackle?    $m/s$

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26#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 12,600-kg railroad car travels alone on n 4k++53 oqfz),qf lqmuld0o oalevel frictionless track with a constant speed of 18m/s A 5350-kg lo fdf4lq 5m +oolqknq),z3+u 0oad,initially at rest, is dropped onto the car. What will be the car’s new speed?    m/s

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27#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 9300-kg boxcar trave6zfhu(;+ mqzeqpk4 2rd6qor.ling at $15 \; m/s$ strikes a second boxcar at rest. The two stick together and move off with a speed of $6 \; m/s$ What is the mass of the second car?    $m/s$

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28#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  During a Chicago storm, winds can whip h8gw( aomf*6l korizontally at speeds of 100km/h If the air strikes a person at the rate of 40kg/s per square meter and is brought to rest, estimate the force of the wind on a person. Assume the person is 1.50 m high and 0.50 m wikw*amf(8g o6lde. Compare to the typical maximum force of friction $\mu\approx1.0$ between the person and the ground, if the person has a mass of 70 kg.    N
$F_{on person}$   $F_{fr}$

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29#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 3800-kg open railroad car coasts along with a constant spe;xe84hj8li 9t u7v rgaed of 8.6m/s on a level track. Snow begins to fall vertically and fills the car at a rate of 3.5kg/min Ignoring friction with the tracks, whatj 4x7 8ght98var iuel; is the speed of the car after 90.0 min?$\approx$    m/s

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30#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An atomic nucleus initially moving at 420m/s ex/nqg9 49k qhmmits an alpha particle in the direction of its velocity, and the remaining nucleus slows to 350m/s If the alpha particle has a mass of 4.0 u and the original nucleus has a mass of 222 u, what speed does the alpha particle have when it xh k/q9q4gmn 9is emitted?    m/s

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31#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 23-g bullet traveling 230m/xsvq;ge l.s kn39ph57.vi5k qs penetrates a 2.0-kg block of wood and emerges cleanly at 170m/s If the block is statih. ; 5ik57gqs e9vlsnvk qxp3.onary on a frictionless surface when hit, how fast does it move after the bullet emerges?    m/s

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32#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 975-kg two-stage rocket is traveling5k9nhi ( -cdmm at a speed of $5.80\times10^3\mathrm{~m/s}$ with respect to Earth when a pre-designed explosion separates the rocket into two sections of equal mass that then move at a speed of $2.20\times10^3\mathrm{~m/s}$ relative to each other along the original line of motion. Let “A” represent the upper stage (that moves away faster) and “B” represent the lower stage.
(a) What are the speed and direction of each section (relative to Earth) after the explosion? $v'_A$   m/s    $v'_B$   m/s  
(b) How much energy was supplied by the explosion? [Hint: What is the change in KE as a result of the explosion? $a\times10^8$ a =    J

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33#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A rocket of total mass 3180 kg is traveling in outer space with a sg91+) +uw b glrr ..ofle*rgja*cj4c velocity of 115m/s To alter its col1j*g9bg.)o+lr r* +a.4gw ejrcfcus urse by 35.0 $^{\circ} $, its rockets can be fired briefly in a direction perpendicular to its original motion. If the rocket gases are expelled at a speed of 1750m/s how much mass must be expelled?    kg

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34#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A golf ball of mass 0.045 kg is hit o 9y:m7x,s zbdsff the tee at a speed of 45m/s The golf club was in contact with the b:s7y m9sxz,dball for $3.5\times10^{-3}$s Find (a) the impulse imparted to the golf ball,    kg*m/s
(b) the average force exerted on the ball by the golf club.    N

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35#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 12-kg hammer strikes a nail at a velodu ae3hc 5,w:x7z4 yfbcity of 8.5m/s and comes to rest in a time interval of 8.0 ms. (a) What is the ib7hxawz5ecf4 yu3, :dmpulse given to the nail?    kg*m/s
(b) What is the average force acting on the nail?    N

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36#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A tennis ball of mass *z6m;1rpld hke btg22w 5ej 6upk;x/hm=0.06kg and speed v=25m/s strikes a wall at a 45 $^{\circ} $ angle and rebounds with the same speed at 45 $^{\circ} $ (Fig. 7–32). What is the impulse (magnitude and direction) given to the ball?   kg*m/s to the  


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37#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You are the design engineer in charge of the crashworthinessj 3bqm +kk,s3qrmqc5us r*)8 :if5kma of new automobile models. Cars are tested by smashing them into fixed, massive barriers at 50km/h (30 mph). A new model of mass 1500 kg takes 0.15 s from the time of impact untir3) q3skamqmcf,+m85s:* j k 5kbr quil it is brought to rest. (a) Calculate the average force exerted on the car by the barrier. $\approx$$a\times10^5$N a =   
(b) Calculate the average deceleration of the car.    m/$s^2$

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38#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 95-kg fullback is running at 4m/s to the east a.e6 *u;tb7qe h bsc5rgnd is stopped in 0.75 s by a head-on tackle by a tackler running det;c7b 5eq6.uhbr* gs ue west. Calculate
(a) the original momentum of the fullback    kg*m/s
(b) the impulse exerted on the fullback    kg*m/s
(c) the impulse exerted on the tackler,    kg*m/s
(d) the average force exerted on the tackler.    N

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39#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Suppose the force acting on a tennis ba - kyr3/mp06vinsd kb1ll (mass 0.060 kg) points in the +x direction and is given by the graph of d630/vb k-nr 1 kpyimsFig. 7–33 as a function of time. Use graphical methods to estimate
(a) the total impulse given the ball    N*s
(b) the velocity of the ball after being struck, assuming the ball is being served so it is nearly at rest initially.    m/s



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40#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  From what maximum height can a 75-kg person jump without breaking the l)sbig afh 0y9fve *c32ower leg bone of either leg? Ignore air resistance and assume the CM of the person moves a distance of 0.60 m from the a 9)ey g0i *2sbvf3hfcstanding to the seated position (that is, in breaking the fall). Assume the breaking strength (force per unit area) of bone is $170\times10^6\mathrm{~N/m^2}$ and its smallest cross-sectional area is $2.5\times10^{-4}m^2$ [Hint: Do not try this experimentally.]    m

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41#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A ball of mass 0.440 kg moving east (+x direction) wdo 7rmd+f( /kpbno(iz s9w f:+ith a speed of collides head-on with a 0.220-kg ball at rest. If the collision is perfectly elastic,:/w( fbr d kioom 9+z(psnf+d7 what will be the speed and direction of each ball after the collision?Let A represent the 0.440-kg ball, and B represent the 0.220-kg ball. $v'_A$    m/s    $v'_B$    m/s  

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42#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 0.450-kg ice puck, moving east with a speed of 3m/s has a head-on collisw ;yx6c,xng w*ion with a 0.900-kg puck initially at rest. Assuming a perfectly elastic collision, what will be the speed and direction of each object after the collision?Let A represewcx 6n*wx;g,ynt the 0.450-kg puck, and let B represent the 0.900-kg puck. v'$_A$ =    m/s   v'$_B$ =    m/s 

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43#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two billiard balls of equal mass undergo a perfectly elas vld5hy,kvmt8 gz5.,l tic head-on collision. If one ball’s initial speed was 2m/s and the other’s was 3m/s in the opposite direction, what will be their speeds after the collision?(Let A represent the ball moving at 2.00 m/s, and call that direction the pv g.v58lmd yk5, l,zhtositive direction.Let B represent the ball moving at 3.00 m/s in the opposite direction. ) v'$_A$ =    m/s v'$_B$ =    m/s

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44#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 0.060-kg tennis balpp9/7 8 *fqleu odzy/zl, moving with a speed of 2.5m/s collides head-on with a 0.090-kg ball initially moving away from it at a speed of 1.15m/s Assuming a perfectly elastic collision, what are the speed and direction of each ball after the collision?(Let A represent the 0.060-kg tennis ball, and let B represent the*ufp89eq /p z d7/lozy 0.090-kg ball.)v'$_A$ =    m/s v'$_B$ =    m/s

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45#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A softball of mass 0.220 kg that is moving with a speed of 8.5m/s cos4)p f 99mensxllides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backward with a speed of 3.7m/s Calcula994nespm ) xsfte
(a) the velocity of the target ball after the collision    m/s
(b) the mass of the target ball.    kg
(Let A represent the moving softball, and let B represent the ball initially at rest.)

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46#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two bumper cars in an amusement park ride collide elastically as one approau zth n6+)kh -e6(mkqmches the other directly from the rhm +t6 km 6h-z(kuq)neear (Fig. 7–34). Car A has a mass of 450 kg and car B 550 kg, owing to differences in passenger mass. If car A approaches at 4.5m/s and car B is moving at 3.7m/s calculate
(a) their velocities after the collision v'$_A$ =    m/s v'$_B$ =    m/s
(b) the change in momentum of each.$\Delta p_{\mathrm{A}}$$\approx$    kg*m/s $\Delta p_{\mathrm{B}}$$\approx$    kg*m/s


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47#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 0.280-kg croquet ball makes an elastic hea9q, w o.u-)p0 g6vymedalhmy1d-on collision with a second ball initially atoy1 gdu0a) ,m9.hy w6qpelvm- rest. The second ball moves off with half the original speed of the first ball.
(a) What is the mass of the second ball?    kg
(b) What fraction of the original kinetic energy $(\Delta\mathrm{kE/KE})$ gets transferred to the second ball?   

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48#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In a physics lab, a cube slides down a frictionless incline as shown in Fig5wt*x- /uxa ed. 7–35, and elastically strikes another cube at the bottom that is only one-half its mass. If the in-dxax*utew 5 /cline is 30 cm high and the table is 90 cm off the floor, where does each cube land? [Hint: Both leave the incline moving horizontally.]$\Delta x_{m}$$\approx$    m $\Delta x_{M}$$\approx$    m


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49#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
ake the general case of i:z1miq ba t 5yf9b77xan object of mass m$_A$ and velocity v$_A$ elastically striking a stationary object of mass head-on. (a) Show that the final velocities v'$_A$ and v'$_B$ are given by$v_{\mathrm{A}}^{\prime}=\left(\frac{m_{\mathrm{A}}-m_{\mathrm{B}}}{m_{\mathrm{A}}+m_{\mathrm{B}}}\right)\nu_{\mathrm{A}},v_{\mathrm{B}}^{\prime}=\left(\frac{2m_{\mathrm{A}}}{m_{\mathrm{A}}+m_{\mathrm{B}}}\right)\nu_{\mathrm{A}}.$(b) What happens in the extreme case when m$_A$ is much smaller than m$_B$ Cite a common example of this. (c) What happens in the extreme case when m$_A$ is much larger than m$_B$ Cite a common example of this. (d) What happens in the case when m$_A$=m$_B$ Cite a common example.
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50#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In a ballistic pendulum experiment, projectile 1 results in a maximum height h bs q8-xjma )w(of the pendulum 8(aj qw-)mbxsequal to 2.6 cm. A second projectile causes the the pendulum to swing twice as high, $h_2=5.2\mathrm{cm}$ The second projectile was how many times faster than the first? $v_1$ =    $v_2$ ([color=rgba(0, 0, 0, 0.85)]Round to three decimal places)

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51#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 28-g rifle bullet traveling 230m/s buries itself in a eup:hoyt82taw43 g9xv4g. qj:5j wlm3.6-kg pendulum hanging on a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine the vertical and horizontal components of the 9puam 4vgxo h84t5wwt3l y: 2:gjej.q pendulum’s displacement.vertical$\approx$    m horizontal =    m

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52#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
(a) Derive a formula for the fr.emlzcky fx1 l0opf;h0v 3 9+uaction of kinetic energy lost, $(\Delta\mathrm{KE/KE})$ for the ballistic pendulum collision of Example 7–10. (b) Evaluate for m=14g and M=380g
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53#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An internal explosion breaks an object, initially at rest, into two pignz:lfmp)g)58 s* qvaeces, one of which has 1.5 times the mass of the other. If 7500 J were released in the explosion, how much kinetic energy did each piece acquire? (Let A re)flpng * sz5mv: qa)g8present the heavier particle, and B represent the lighter particle. ) KE'$_A$ =    J KE$_B$ =    J

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54#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 920-kg sports car collides into the rear u ) x7ngo)l9zr-ax:e aend of a 2300-kg SUV stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8 m before stopping. The poli g)ex7)x-au :a n9lrozce officer, knowing that the coefficient of kinetic friction between tires and road is 0.80, calculates the speed of the sports car at impact. What was that speed?(Let A represent the sports car, and B represent the SUV) $\approx$    m/s

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55#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A ball is dropped from a height of 1.50 m and rebounds to a height of 1.20 m. +suqd 9sq 2er5Approximately how many r r esu5dq+92qsebounds will the ball make before losing 90% of its energy?   

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56#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A measure of inelasticity in a head-on collision of two objects is the coeffi o6g12y g*:lv rp.knsp 0xcnvp/8. pjkcient of restitution, e, defined xc:k. ry6pnn pgp*20pkg 8svvj/o .1las$e=\frac{\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}}{\nu_\mathrm{B}-\nu_\mathrm{A}},$
where $\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}$ is the relative velocity of the two objects after the collision and $\nu_\mathrm{B}-\nu_\mathrm{A}$ is their relative velocity before it.
(a) Show that e=1 for a perfectly elastic collision, and e=0 for a completely inelastic collision.
(b) A simple method for measuring the coefficient of restitution for an object colliding with a very hard surface like steel is to drop the object onto a heavy steel plate, as shown in Fig. 7–36. Determine a formula for e in terms of the original height h and the maximum height h’ reached after one collision.

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57#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A wooden block is cut into two pieces, ordbm u.5 p.sl;6tpyb8- 4 udawne with three times the mass of the other. A depression is made in both faces of the cut, so that a firecracker can be placed in it with the block reassembled. The reassembled block is set on a rough-surfaced table, and the fuse is lit. When the firec4r.ds6 ypumb;u-abp.t l w58d racker explodes, the two blocks separate and slide apart. What is the ratio of distances each block travels? 

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58#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 15.0-kg object moving in th(nppp*s i (ue,qp8:hfe (dl6ve +x direction at 5.5m/s collides head-on with a 10.0-kg object moving in the -x direction sp*p e6 pf:,e q p(l(u(8dhnviat 4m/s Find the final velocity of each mass if:
(a) the objects stick together;   m/s
(b) the collision is elastic; v'$_A$ =    m/s v'$_B$ =    m/s
(c) the 15.0-kg object is at rest after the collision;   m/s 
(d) the 10.0-kg object is at rest after the collision;   m/s 
(e) the 15.0-kg object has a velocity of 4m/s in the -x direction after the collision. .   m/s 
Are the results in (c), (d), and (e) “reasonable”? Explain
( Let A represent the 15.0-kg object, and let B represent the 10.0-kg object.)

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59#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A radioactive nucleus at rest decays into a second nu7n ;zya ebpqfy21-f d/cleus, an electron, and a neut 2ab7d ep y1-n/yq;zffrino. The electron and neutrino are emitted at right angles and have momenta of $9.30\times10^{-23}kg\cdot m/s$ and $5.40\times10^{-23}\mathrm{~kg}\cdot\mathrm{m/s}$ respectively. What are the magnitude and direction of the momentum of the second (recoiling) nucleus?    $ \times10^{-22}$    $^{\circ} $ from the momentum of the electron

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60#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An eagle ($m_{\mathrm{A}}=4.3\mathrm{kg}$) moving with speed $\nu_\mathrm{A}=7.8\mathrm{~m/s}$ is on a collision course with a second eagle ($m_{\mathrm{B}}=5.6\mathrm{kg}$) moving at $\nu_{\mathrm{B}}=10.2\mathrm{m/s}$ in a direction perpendicular to the first. After they collide, they hold onto one another. In what direction, and with what speed, are they moving after the collision? v =    m/s $\theta$ =    $^{\circ} $ rel. to eagle  

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61#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Billiard ball A of maswl.xnjqslsn 2n 4dy 3 6fs/p*f zjmp0*3-csm.s $m_\mathrm{A}=0.400$kg moving with speed $\nu_\mathrm{A}=1.80$m/s strikes ball B, initially at rest, of mass $m_\mathrm{B}=0.500$kg As a result of the collision, ball A is deflected off at an angle of 30.0 $^{\circ} $ with a speed $\nu_\mathrm{A}^{\prime}=1.10$m/s (a) Taking the x axis to be the original direction of motion of ball A, write down the equations expressing the conservation of momentum for the components in the x and y directions separately. (b) Solve these equations for the speed v'$_B$ and angle $\theta_{\mathrm{B}}$ of ball B. Do not assume the collision is elastic. $\theta_{\mathrm{B}}$ =    $^{\circ} $ v'$_B$ =    m/s

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62#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  After a completely inelastic collision betw cub plzaq;x6-,:1bcveen two objects of equal mass, each having initial speed the two move off together with speed v/3 What was the angle between their ib6qxc:ual; z1bp,c-v nitial directions?    $^{\circ} $

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63#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two billiard balls of equal mass move at right angles and meet at tyae5p7+ 9v sa++vo5k.u,ce/f fkfkmrhe origin of an xy coordinate system. Ball A is moving upward along the y axis at 2m/s and ball B is moving to the right along the x axis with speed 3.7m/s After the collision, assumed elastic, ball B is moving along the positive y axis (Fig. 7–3m79r +,k5vcaey +kpf .v+ o5 efasufk/7). What is the final direction of ball A and what are their two speeds? direction of ball A is   v'$_A$ =    m/s v'$_B$ =    m/s


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64#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A neon atom (m=20u) makej8vh/w /c. kzc; wbia*s a perfectly elastic collision with another atom at rest. After the impact, the hc wv/aiz w8.c*;j/bkneon atom travels away at a 55.6 $^{\circ} $ angle from its original direction and the unknown atom travels away at a -50 $^{\circ} $ angle. What is the mass (in u) of the unknown atom? [Hint: You can use the law of sines.](Let A represent the incoming neon atom, and B represent the target atom) $m_B$   u

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65#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A neon atom (m=20u) makes a perfectly elastic collisqzdrbf6e f86 .ion with another atom at rest.efqd 6rf6.bz8 After the impact, the neon atom travels away at a 55.6 $^{\circ} $ angle from its original direction and the unknown atom travels away at a -50 $^{\circ} $ angle. What is the mass (in u) of the unknown atom? [Hint: You can use the law of sines.](Let A represent the incoming neon atom, and B represent the target atom) $m_B$   u

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66#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Find the center of masctog;4yxc s9 md 9qm(5s of the three-mass system shown in Fig. 7–38. Specify relative to the left-hand 1.00-kg maqtmcyxcgos d(m; 9 459ss.    m


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67#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The distance betweenrishcj;zlv n 1 b/(f. o(z:0hu a carbon atom ($m_{\mathrm{C}}=12\mathrm{u}$) and an oxygen atom ($m_{\mathrm{O}}=16\mathrm{u}$) in the CO molecule is $1.13\times10^{-10}$m How far from the carbon atom is the center of mass of the molecule?    $\times10^{-11}$m

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68#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The CM of an empty 1050-.r;tb*.jw p6ncoe 7 mfkg car is 2.50 m behind the front of the car. How far from the front of the car will the CM be when two people sit in the front seat 2.80 m from the front of the car, and three people sit in the back seat 3.90 m. jc7t . *omfw;n6rpbe from the front? Assume that each person has a mass of 70.0 kg.    m

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69#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A square uniform raft, 18 m by 18 m, o 2,jhr.ecgfjhey x/fx .1sna(*95ixq f mass 6800 kg, is used as a ferryboat. If three cars, each of mass 1200 kg, occupy its NE, SE, and SW cog/5jnx.x.f(2ehsc qf19ar jy,*e x hirners, determine the CM of the loaded ferryboat.$X_{CM}$ =    m $Y_{CM}$ =    m

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70#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Three cubes, of sides rpx+ j7 qot3afhrs .)5$l_0$,$2l_0$, and $3l_0$ are placed next to one another (in contact) with their centers along a straight line and the $l=2l_{0}$ cube in the center (Fig. 7–39). What is the position, along this line, of the CM of this system? Assume the cubes are made of the same uniform material. $X_{CM}$ =    $l_0$ from the    edge of the smallest cube



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71#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A (lightweight) pallet has a load of identical cases of tomato paste (s5o1ig,p g k fdqvp1/9v5p9om lww u2,yee Fig. 7–40), each of which is a cube of length l. Find the center of gravity in thegugyl/fk 5wp9q,o19v1v25dm,ppw o i horizontal plane, so that the crane operator can pick up the load without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l



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72#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A uniform circular plate of radius agf,d 4n3tl7r7iuw t 7qiw01d2R has a circular hole of radius R cut out of it. The center of the smaller circle is a distance 0.80R from the cetti7f a0 i7w4 gq ddw1,7lunr3nter C of the larger circle, Fig. 7–41. What is the position of the center of mass of the plate? [Hint: Try subtraction.]   R


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73#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Assume that your proportions are the same asid im7vd +;.zb those in Table 7–1, and calculate the mass of one mi d.b7 +;vidzof your legs.    kg


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74#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Determine the CM of an out5 fykm-4e7z jhvyoq (,-crvu*stretched arm using Table 7–1.   % of the person's height along the line from the shoulder to the hand


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75#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Use Table 7–1 to calculate the position of the CM of an arm - +c5nzonea;q bent at a right angle. Assume that the persoq+5-ncz eoa n;n is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm


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76#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
When a high jumper iyje z i888,)sp md.mry+pm a1ss in a position such that his arms and legs are hanging vertically, and his trunk and head are horizontal, calculate how far below the torso’s median line the CM wiydmp .8mp 18 jais,ez8+ysr) mll be. Will this CM be outside the body? Use Table 7–1.
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77#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The masses of the Earth and Moon4 9wbkork8ma : are $5.98\times10^{24}$kg and $7.35\times10^{22}$kg respectively, and their centers are separated by $3.84\times10^{8}$m (a) Where is the CM of this system located? (b) What can you say about the motion of the Earth–Moon system about the Sun, and of the Earth and Moon separately about the Sun?
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78#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 55-kg woman and an 80-kg man stand 10.0 m apart on friction5 k; x snb99v9 ztx5w9numvf,nless ice.
(a) How far from the woman is their CM?    m from the woman
(b) If each holds one end of a rope, and the man pulls on the rope so that he moves 2.5 m, how far from the woman will he be now?    m
(c) How far will the man have moved when he collides with the woman? He has moved    m from his original position

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79#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A mallet consists of a uniform cylindrical head of mass 2.00 kg and a diamete2on7l p),z ducio, :d39uelqpr 0.0800 m mounted on a unifoeol:u9 p,d3 zilu p,)7nqd2 corm cylindrical handle of mass 0.500 kg and length 0.240 m, as shown in Fig. 7–42. If this mallet is tossed, spinning, into the air, how far above the bottom of the handle is the point that will follow a parabolic trajectory?    cm

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80#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A mallet consists of a uniform cylindriy aup.oge jzq7-./v4u*k p* snej95whcal head of mass 2.00 kg and a diameter 0.0800 m mounted on a uniform cylindrical handle of mass 0.500 k 9y *5/*uwgnhs7ep qjzk- evu ..jpa4og and length 0.240 m, as shown in Fig. 7–42. If this mallet is tossed, spinning, into the air, how far above the bottom of the handle is the point that will follow a parabolic trajectory?    d    d


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81#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) Suppose that in Example 7–14 dyv- x8c (c .m:vo3mh03scsmu (Fig. 7–29), $m_{II}$=3$m_{I}$ Where then would $m_{II}$ land?    d(Round to two decimal places)
(b) What if $m_{I}$=3$m_{II}$    d


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82#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A helium balloon and its gondola, of mass M, are in e3(;vdw7/yabt (ynjuthe air and stationary with respect to the ground. A passenger, of mass m, then climbs out and slides down a rope with speed measured with respect to the balloon. With what speed and dirb/w 7uv( e(d 3taj;ynyection (relative to Earth) does the balloon then move? What happens if the passenger stops?
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83#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An 0.145-kg baseball pitched horizontally at strikes a bat and is porp li. d0z74p3jyy.*3gsguiw pped straight up to a height ofy i lsdug.yz3.r470 ipg*wj3p 55.6 m. If the contact time is 1.4 ms, calculate the average force on the ball during the contact.    $^{\circ} $

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84#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A rocket of mass m traveling with7z+ b ykiv8pzg019ess speed $v_0$ along the x axis suddenly shoots out fuel, equal to one-third of its mass, parallel to the y axis (perpendicular to the rocket as seen from the ground) with speed 2$v_0$ Give the components of the final velocity of the rocket.$P_x$: v'$_x$=    $v_0$
$P_y$: v'$_y$=    $v_0$

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85#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A novice pool player is faced with the corner pocket i ihwg/daj5 h2o3y2k53c/ nuw shot shown in Fig. 7–43. Relative dimensions are also shown. Should the player be worried about this being a “scratch shot,”j2 5w ak5dh3/yo3/2 wihcnuig in which the cue ball will also fall into a pocket? Give details.
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86#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 140-kg astronaut (including space suit) acquir:mprc yr 1+e7qes a speed of 2.5m/s by pushing off with his legs from an 1800-kg spa r qr7y:p+em1cce capsule.
(a) What is the change in speed of the space capsule?    m/s
(b) If the push lasts 0.40 s, what is the average force exerted on the astronaut by the space capsule? As the reference frame, use the position of the space capsule before the push.    N

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87#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two astronauts, one of mass 60 kg and the othe- 2 ouomlbd : ze/gh5i)qymi;) u0ehn(t-nfr)r 80 kg, are initially at rest in outer space. They then push each other apart. How far apart are they when the lighter astronaut has movb/f)i-z :nidh)mrt(-qm205eo; ne) oyg uuhled 12 m?    m

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88#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A ball of mass m makes a head-on e b2s2t,bvh0qbbtm2j 1lastic collision with a second ball (at rest) and rebotm0 t,2 bq12bbjsv2 bhunds in the opposite direction with a speed equal to one-fourth its original speed. What is the mass of the second ball? $m_B$ =    $m_A$(Round to two decimal places)

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89#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You have been hired as an expert witness in a court case involving an automobile4 +xwa5e mxl8 )cndnm. accident. The accident involved car A of mass 1900 kg which crashed into stationary car B of mass 1100 kg. The driver of car A applied his brakes 15 m before he crashed into car B. After the collision, car A slid 18 m while car B slid 30 m. The coefficient of kinetic friction between the locked wheels and thxm4xwal5 nd.8cem n)+ e road was measured to be 0.60. Show that the driver of car A was exceeding the 55-mph (90km/h) speed limit before applying the brakes.    mi/h

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90#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A golf ball rolls off theqng lkopts, .etl.5+d./e( hv top of a flight of concrete steps of total vertical height 4.00 m. The ball hits four times on the way down, each time striking the horizontal part of a different step 1.0 m lower. If all collisions are perfectly elastic, what is the bounce height on the fourth bounce when the / oev .dp.ltn,l+q.gtk eh(5sball reaches the bottom of the stairs?
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91#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bullet is fired vertically into a 1.40-kg block of )tlzi6 5k7w 4 1npepjzwood at rest directly above it. If the bullet has a mass of 29.0 g w7zjip1 l4 6p)5ntz ekand a speed of 510m/s how high will the block rise after the bullet becomes embedded in it?    m

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92#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 25-g bullet strikes and becomes embedded in a 1.35-kg ,)0qizb/ p adj ps+c5ablock of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.25, and the impact drives the bloc p c0qa/i+jzp)d5 b,sak a distance of 9.5 m before it comes to rest, what was the muzzle speed of the bullet?    m/s

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93#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two people, one of mass 75 kg and the other of mass 60 kg, sit in a rowboat ho0x qu.pj4oyu, ,(;n fco3ggof mass 80 kg. With the boat initially at rest, the tgxoun.03 o,of hgc(uy4,qjp ; wo people, who have been sitting at opposite ends of the boat 3.2 m apart from each other, now exchange seats. How far and in what direction will the boat move? The boat will move    towards the initial position of the 75 kg person(Round to two decimal places)

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94#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A meteor whose mass wa i1y-ne6b j-3)lws2v: xntgqp s about $ 1\times10^{ 8}$kg struck the Earth ($m_E$=$6 \times10^{ 24}$kg) with a speed of about 15km/s and came to rest in the Earth.
(a) What was the Earth’s recoil speed?    $ \times10^{-13 }$m/s
(b) What fraction of the meteor’s kinetic energy was transformed to kinetic energy of the Earth?    $ \times10^{ -17}$
(c) By how much did the Earth’s kinetic energy change as a result of this collision?    J

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95#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An object at rest is suddenly broken apart (022a+wu)i +m6 s4 4yihdqb o /kljkb lelcl9vinto two fragments by an explosion. One fragment acquirel(hy +)a 69 cbib4 d owmujk/2lqv0+4lk 2lseis twice the kinetic energy of the other. What is the ratio of their masses?   

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96#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The force on a bullet is given by the njc1m6u *s8+yew /nj *qtbtc-formula F = 580-( $1.8 \times10^{ 5}$t) over the time interval t=0 to t = $3.0 \times10^{-3 }$s In this formula, t is in seconds and F is in newtons.
(a) Plot a graph of F vs. t for t=0 to t=3.0ms
(b) Estimate, using graphical methods, the impulse given the bullet.    N*s
(c) If the bullet achieves a speed of 220m/s as a result of this impulse, given to it in the barrel of a gun, what must its mass be?    kg

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97#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two balls, of massesi+ cxwahm9r::9 z,skk $m_A$ = 40g and $m_B$ = 60g are suspended as shown in Fig. 7–44. The lighter ball is pulled away to a 60$^{\circ} $ angle with the vertical and released.
(a) What is the velocity of the lighter ball before impact?$\approx$    m/s
(b) What is the velocity of each ball after the elastic collision?v'$_A$ $\approx$    m/s v'$_B$ $\approx$    m/s(Round to two decimal places)
(c) What will be the maximum height of each ball after the elastic collision?    m


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98#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An atomic nucleus at rest decays radi(j)xscmbuy ; h(.y z-lr;(tjioactively into an alpha particle and a smaller nucleus. What will be the speed of this recoiling nucleuszyl;(yj mrh)u. (;cx(-bt sji if the speed of the alpha particle is $ 3.8\times10^{5 }$m/s Assume the recoiling nucleus has a mass 57 times greater than that of the alpha particle.    m/s

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99#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 0.25-kg skeet (clay target) is firedro -2*gb(2 ol9awiege at an angle of 30 $^{\circ} $ to the horizon with a speed of 25m/s (Fig. 7–45). When it reaches the maximum height, it is hit from below by a 15-g pellet traveling vertically upward at a speed of 200m/s The pellet is embedded in the skeet.
(a) How much higher did the skeet go up?    m
(b) How much extra distance, $\Delta{x}$ does the skeet travel because of the collision? $\approx$   


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100#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A block of mass m=2.2kg slides o(7o wd2- piyrdown a 30.0 $^{\circ} $ incline which is 3.60 m high. At the bottom, it strikes a block of mass M=7kg which is at rest on a horizontal surface, Fig. 7–46. (Assume a smooth transition at the bottom of the incline.) If the collision is elastic, and friction can be ignored, determine
(a) the speeds of the two blocks after the collision,v'$_A$ =    m/s v'$_B$ =    m/s
(b) how far back up the incline the smaller mass will go. $\approx$   (Round to the nearest integer) (Let A represent mass m, and B represent mass M.)


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101#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In Problem 79 (Fig. 7–46), what is 9oi- v)m0tiqpthe upper limit on mass m if it is to rebound from M, slide up t)o9 i-qpmvt i0he incline, stop, slide down the incline, and collide with M again?    kg (Let A represent mass m, and B represent mass M.)


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102#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The gravitational slingshot effect. Figure 7–47 showsk(nz/*v8w)5n0 dk gdgzsw -xg the planet Saturn moving in the negative x direction at its orbital speed (with respect to thegw/0*5wz -( dd g)n8kknzvs gx Sun) of 9.6km/s The mass of Saturn is $5.69 \times10^{ 26}$kg A spacecraft with mass 825 kg approaches Saturn. When far from Saturn, it moves in the direction at 10.4km/s The gravitational attraction of Saturn (a conservative force) acting on the spacecraft causes it to swing around the planet (orbit shown as dashed line) and head off in the opposite direction. Estimate the final speed of the spacecraft after it is far enough away to be considered free of Saturn’s gravitational pull.    km/s


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