We claim that momentum is cor,+m xezgyv3cyf+4 d *nserved, yet most moving objects eventually slow down and stop. E3v e+dmzy4gc, y+r *fxxplain.

When a person jumps from a treeqhpd sb sq5: 6:64isze to the ground, what happens to the momentum of the person upon striking the grou: h 5sdqeq46 6s:ipzsbnd?

When you release an inflated but untied balloonf +ej e:cirz:8, why does it fly across the room+8eejzc :: rif?

It is said that in ancient times a rich maq :j(wrwv )z41i/dds jn with a bag of gold coins froze to death while stranded on a frozen lake. Beca:d4dswq/)1v j zijwr (use the ice was frictionless, he could not push himself to shore. What could he have done to save himself had he not been so miserly?

How can a rocket changei b,oz 6y6it7fm+v/p b direction when it is far out in space and is essentially in a vacy7i6 /pv6bzb+ift, mouum?

According to Eq. 7–5, the longer the impact time of an imp:hnbcbgbey9 za 7,,85 sav,gqulse, the smaller the force can be for thecvas,ne,z9 75bqgah g:b b8y, same momentum 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.

Cars used to be built as rigid as possibley+e je; fp /eg7qys7c/ :iqp)a to withstand collisions. Today, though, cars are designed to have “crumple zones” that collapse upon impact. What is the advantage of thip/pe7iy7 cj qe) faesg/ :qy;+s new design?

Why can a batter hit a pitched baseball fu3wdo-a6al1)ld*tg8 aieo 3vv -oxdn 4rther than a ball tossed in the air by the b wd)ngv4-vt lae oad 363*l-doi1xao8atter?

Is it possible for an object to receive a larger impulse from +a:3 p y5xqinja small force than from a large force? Explain.q ip:+ajy5n3 x

A light object and a heavy object have the samc/ wskn z*i50me kinetic energy. Which has the greater momi/ sm* nkz05cwentum? Explain.

Describe a collision in which all kinetic energy iswic(bis; )1r0m elx j3 lost.

At a hydroelectric power plant, water ist syu+-*z-zxo guf) 6k:+oe9x pc hsx3 directed at high speed against turbine blades on an axle that turns an electric generator. For maximum poweukspsfox tzgyc +h9e)-u3 + 6*x -:zoxr generation, should the turbine blades be designed so that the water is brought to a dead stop, or so that the water rebounds?

A squash ball hits a wall at a 451tlb mgq;6dv 7 $^{\circ} $ angle as shown in Fig. 7–30. What is the direction (a) of the change in momentum of the ball, (b) of the force on the wall?

A Superball is dropped from a height h onto a hard steel plate (fixed to the)l u2 t0m.sdzlm0u (yt Earth), from which it rebounds at very neay0 sl0du lz2(mt m)tu.rly 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.

Why do you tend to lean backward when carrh,x3dl a 1 2yneggj4rfnyk309ying a heavy load in your arms?

Why is the CM of a 1-m length o2ys v(cd.sp 5rf pipe at its mid-point, whereas this is not true f (dp5c.vs rys2or your arm or leg?

Show on a diagram how your CM shifts when56 iqq.rv-*hrrwt3hm you change from a lying position to a sitting qv .6r tr*iw3 hrm-h5qposition.

If only an external force can change the momentum of the cegf(q5aec b;. knter of mass of an object, how can the internal force of an engine accq5g( ca fkbe;.elerate a car?

A rocket following a parabolic path through the li7o 35xov8ph1bmr7mhq h/1e air suddenly explodes into many pieces. What can you say about the motion of this system of pie/18hqh vb m5l 31oem7hrp 7ixoces?

  What is the magnitude of the momentum of a 28-g sparrow flying with a speed of ob2nzm( emv/;t+g 6 jl8.4 m;tbzm lo/v2( e6j+ngm/s    $kg\;m/s$

  A constant friction force of 25 N acts on a 65-kg skier for 20 s. Wv)c,jp h,zem( iq f6u5hat is the skier’s changei) u5c6,,hqepz m vfj( in velocity?    m/s

  A 0.145-kg baseball pitched at 39 m/s 6u(b6mcs4zr8ril bm*eo j2l8is hit on a horizontal line drive straight back toward the pitcher at 52m/s If the contacim jl 8*rebc6lb28sz(ur 6mo 4t time between bat and ball is $3\times10^{-3}$s calculate the average force between the ball and bat during contact.    N

  A child in a boat throws a 6.40-kg package oe qvzpdlt*q(-: .2yg7 los0 va2yow:rut horizontally with a speed of 10 m/s Fig. below Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the a*q 7:p-gsywoq vo:2lld2e.r(v y t0zchild is 26.0 kg, and that of the boat is 45.0 kg. Ignore water resistance. The velocity of the boat is    m/s

  Calculate the force exerted on a rocket, given that the propelling gases ark5sto.g: ismb4 87z swe expelled at a8sbmwgt.7 5s4 koi :sz rate of 1500kg/s with a speed of $ 4\times10^{4 }$ (at the moment of takeoff).$a\times10^7$ N a =   

  A 95-kg halfback moving at 4.1m/s on an apparent breakaway for a touch2go2ds9 oj) nmdown is tackled from behind. When he was tackled by an 85-kg cornerback running at 5.5m/s in the same direction, what was their mutual speed immediately after the d22o9)j monsgtackle?    m/s

  A 12,600-kg railroad car travels alone on alevel frictionless track with a conbd2 b+9 shoui:stant speed of 12 9:bdius+ boh8m/s A 5350-kg load,initially at rest, is dropped onto the car. What will be the car’s new speed?    m/s

  A 9300-kg boxcar traveling at 15m/s strikes a second 76aofiw,d8 j pv k*7biboxcar at rest. The two stick together and move off with a speed of 6m/s What is 7ip,ad*7bwk8j v f 6iothe mass of the second car?    m/s

  During a Chicago storm, winds can wtr an*c9 1a q7ihk1z0yhip horizontally at speeds of 100km/h If the air strikes ait7r*nqa hy0 ckz9a11 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 wide. 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
$F_{on person}$  ----待选择----<> $F_{fr}$

  A 3800-kg open railroad car coasts along with a constant spee9-inj nvib. v+;5rpbld of 8.6m/s on a level track. Snow begins to fall vertically and fills the car at a v b nnvir l+j;-9.5ipbrate of 3.5kg/min Ignoring friction with the tracks, what is the speed of the car after 90.0 min?$\approx$    m/s

  An atomic nucleus initially moving at 420m/s emits an alpha particle in thsf7-zi 5ojn:q as6-xte 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 is ea 7joqs-sztf65 :x-ni mitted?    m/s

  A 23-g bullet traveling 230m/s penetrates a 2.0-kg block of wood and emeri45y w6si e5v, mqzsw*bxao) 8ges cleanly at 170m/s If the block is stationary on a frictionless surface when hit, how fast doeb4eqv)5iyz smsiawx8 5*,o 6 ws it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket is trw k ze.0sk4u7gaveling 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  ----待选择----away from the Earthtowards the Earth  $v'_B$   m/s  ----待选择----away from the Earthtowards the Earth 
(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

  A rocket of total mass 3180 kg k8 x-rn gx 4hiso;e9/kis traveling in outer space with a velocity of 115m/ 8;4-xne kxisk 9rhog/s To alter its course 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

  A golf ball of mass 0.045 kg is hit of ;k qre.8pr: kig6tan3f the tee at a speed of 45m/s The golf club was in contact with tha6i k3:qtre.pkr;8gn e ball 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

  A 12-kg hammer strikes a nail at a velocity of 8.5m/s and ispmi,asfv (4.(h w;o. b duhnpdl-+2comes to rest in a time interval of 8.0 ms. (a) What is the ;hi. pa4(idp s,v(n+ 2.fos wdb -ulhmimpulse given to the nail?    kg*m/s
(b) What is the average force acting on the nail?    N

  A tennis ball of mass m=0.06kg and splq v4wy h hiilp88/f/1eed 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  ----待选择----leftright 

  You are the design engineer in charge of the crashwone2zd7r( ;lv 01vk a9btm/ jjkrthiness 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 untilze7lkjn bv9( tv d;k/jm02a1 r 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$

  A 95-kg fullback is runni8 is5qkr na-a6a 4i1ding at 4m/s to the east and is stopped in 0.75 s by a head-on tackle by a ta8k1r6i-sqi d5 ia ana4ckler running due 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

  Suppose the force acting on a tennis ball (mass 0.060 kg) points in the +x dir* euf3x d- j-e.mrt8yoection and is given by the graph of Fig. 7–33 as a function of time. Use graphical methods to est8md-*yt .3r ofex- jeuimate
(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

  From what maximum height can a 75-kg penuns( 3 zl/qjdf(8c 4/vy j;umrson jump without breaking the lower leg bone of either leg? Ignore air resistance and assume the CM of the person moves a distance of 0.60 m from the standing to the seated position (that is, in breaking the fall). Assume the vnd; m/ns zu ujcqj4(8yf /l3(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

  A ball of mass 0.440 kg moving east (+x direction) with a speed of colliduv 1c1c9n; i48 eshtukes head-on with a 0.220-kg ball at rest. If the collision is perfectly elastic, what will be the speed;9 is1h8 nutkv1ucc4 e 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  ----待选择----eastwest  $v'_B$    m/s  ----待选择----eastwest 

  A 0.450-kg ice puck, moving east with a speed of 3m/s has a head-on collision s;p( e2eeo r0vwith a 0.900-kg puck initially veorse( p20e ;at rest. Assuming a perfectly elastic collision, what will be the speed and direction of each object after the collision?Let A represent the 0.450-kg puck, and let B represent the 0.900-kg puck. v'$_A$ =    m/s ----待选择----eastwest  v'$_B$ =    m/s ----待选择----eastwest 

  Two billiard balls of equal mass undergo a perfectly elastic head-on col e/xo crqj4grune3g+f s- ./*nlision. If one bal3e+r xq.f/c/ sogj-4rn* gen ul’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 positive direction.Let B represent the ball moving at 3.00 m/s in the opposite direction. ) v'$_A$ =    m/s v'$_B$ =    m/s

  A 0.060-kg tennis ball, moving with a speed of 2.5m/s collides head-on with a 0p6s u9wn sbfk/gc *e1.gm70pw58bwhg.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 0.060ukgg hw6mpe7f s .pwng15 c08bb9s/w*-kg tennis ball, and let B represent the 0.090-kg ball.)v'$_A$ =    m/s v'$_B$ =    m/s

  A softball of mass 0.220 kg that is moving with8+ fe n3-xfici a speed of 8.5m/s collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backward witi-if3e8cxfn +h a speed of 3.7m/s Calculate
(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.)

  Two bumper cars in an amusement park 9c48 qazh :ik 4 h5ou hzr37ic6znfhd)ride collide elastically as one approaches the other directly from the rear (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 mou q 54 c)nzi8rd476f3ohichhaz9kh :z ving 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

  A 0.280-kg croquet ball makes an elasg 1lrk /l nc29pkb+3bjtic head-on collision with a second ball initially at rest. The second ball moves off with half the original speed of the first ball. 3glbl+k/p1k j 2r9cn b
(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?   

  In a physics lab, a cube slides down a frictionless incline as shown in Fig. 7-1vwcqvhnyq 98mu5*k –35, and elastically strikes another cube at the bottom that is only one-half its mass. If the incline is 30 cm high and the table is 90 cm off the floor, where dqc 5 v mv-n1uy*9whqk8oes each cube land? [Hint: Both leave the incline moving horizontally.]$\Delta x_{m}$$\approx$    m $\Delta x_{M}$$\approx$    m

ake the general case o 7;erj* f)va6hwoug)hf an 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.

  In a ballistic pendulum experiment, projectile 1 results in a maximum o/.q8y plg3v lheight h of the pendulum equal to 2.6 cm. A second projectile causes the the pendulum to swing twice as high, 8ol qp/vlgy3 .$h_2=5.2\mathrm{cm}$ 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)

  A 28-g rifle bullet traveling 230m/s buries itself in a 3.6-kg pendulum hangingdfd107 zbs2saq 1hw; c on a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine the ve1 c;df zs1w0sb7 hadq2rtical and horizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formula for the fraction of kinetic enek5/dl6m2htz ,rbgo+ cmo wr,3r ;bxc7rgy lost, $(\Delta\mathrm{KE/KE})$ for the ballistic pendulum collision of Example 7–10. (b) Evaluate for m=14g and M=380g

  An internal explosion breaks an object,8 bjf(c hm+*c tyhga,9 initially at rest, into two pieces, 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 represent the heavier particle, and B represent the lighter partj(bfm*8+g t,hyca9 hc icle. ) KE'$_A$ =    J KE$_B$ =    J

  A 920-kg sports car collides into the reir;xf d)r5t9(zsz( dj ar end 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 police officer, knowing that the corzf )59 ;zrjt(x(sddi efficient 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

  A ball is dropped from a hei5ty5 umagm t00- :gyp3m+vkxyg*w7vhght of 1.50 m and rebounds to a height of 1.20 m. Approximately how many rebou0gv0g y yk5m-3p t:vg+7 m my5xtw*uhands will the ball make before losing 90% of its energy?   

A measure of inelasticity in a head-on collision of two objects i(j24m qr/g+ n 3i2sxlor nffl2s the coefficient of restitution, e, defined an 42(2+s3/ror2mxgn lij ffqls$e=\frac{\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}}{\nu_\mathrm{B}-\nu_\mathrm{A}},$
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.

  A wooden block is cut into two pieces, one with three times the mass ok 1ua.,7uquq lz++bj uf the other. A depression is made qu+a 17 qu.l uz+ub,kjin 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 firecracker explodes, the two blocks separate and slide apart. What is the ratio of distances each block travels? ----待选择----1/91/101/81/6 

  A 15.0-kg object moving i zqa2xv+e75/ p kb 0swu;/ h+vsexl.fwn the +x direction at 5.5m/s collides head-on with a 10.0-kg object moving in the -x direction at 4m/s . f zqw7ewsk/v l 2/u+ph;esax+0vx5bFind 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 ----待选择----not reasonable reasonable 
(d) the 10.0-kg object is at rest after the collision;   m/s ----待选择----not reasonable reasonable 
(e) the 15.0-kg object has a velocity of 4m/s in the -x direction after the collision. .   m/s ----待选择----not reasonable reasonable 
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.)

  A radioactive nucleus at rest decays into a slmjo+a0a/5 lnhzz *; zecond nucleus, an electron, and a neutrij 0aln5;h/ao z+*m zzlno. 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

  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  ----待选择----AB 

  Billiard ball A of mass) e8/.urfr jxi $m_\mathrm{A}=0.400$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

  After a completely inelastic collision between two obk74 9o5nhv jbgg8e+scjects of equal mass, each having initial speed the two move off together with speed h9g85 sgen4j7vbo ck+ v/3 What was the angle between their initial directions?    $^{\circ} $

  Two billiard balls ocugo e a:/3v+1t n1jnh:pwga1f equal mass move at right angles and meet at the 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 post3/+cajv gpoag 1e: w n1:hnu1itive y axis (Fig. 7–37). What is the final direction of ball A and what are their two speeds? direction of ball A is  ----待选择----x directionx direction v'$_A$ =    m/s v'$_B$ =    m/s

  A neon atom (m=20u) makes a perfec 0ryorwx15t-qct*ws; tly elastic collision with another atom at rest. After the impc 5*;w yrqr0twx1-os tact, 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

  A neon atom (m=20u) makes a perfectlk nz0vmg/3 jdx ft--pbo 9bt*rd6b3i/y elastic collision with another atom at rest. ri-od6n-9km ftb v3* /b0xg/3tzdpbjAfter 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

  Find the center of mass of tx yncsy hw3hpn7 +7h0bl+9i/4rl j7xohe three-mass system shown in Fig. 7–38. Specify relative to the left-hand 1.x n77h4wryocl /hj03y x ph9l++i7 bsn00-kg mass.    m

  The distance between a ga)yk82zr bxokhl v9g (6:v 9ncarbon 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

  The CM of an empty 1050-kg car is 2.50 m behind the front of thb l zxp7zg+*;gvq-a jyzb79 0se 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 from the front? Assume t z;bzb+g-s 97a xl7jz0gpq*yvhat each person has a mass of 70.0 kg.    m

  A square uniform raft, 18 m by 18 m, of mass 6800 kg, is used as a ferryboat. Iajg6j: eh3ed:f three cars, each of a6 eed3g ::hjjmass 1200 kg, occupy its NE, SE, and SW corners, determine the CM of the loaded ferryboat.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of side;shm4 fax .ab3s $l_0$,$2l_0$, 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  ----待选择----leftright  edge of the smallest cube

  A (lightweight) pallet has a load of identical case .ia: sx *b,4ed (6x2enyboq yev*7zzns of tomato paste (see Fig. 7–40), each of which is a cube of length l. Find the center of gravity in the horizontal plane, so that the crane operator can p,.6z(exo 2iy b* sv nndxea:7qbe*4y zick up the load without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l

  A uniform circular plate of +qr ,v89q4qf 7)fpk z,try6h -o3cyuayz 6adiradius 2R has a circular hole of radius R cut out of it. The center of the smaller circle is a distance 0.804kq v)yp36z,a7fu 9 +iytdo rq,yac6zr -fq8hR from the center C of the larger circle, Fig. 7–41. What is the position of the center of mass of the plate? [Hint: Try subtraction.]   R

  Assume that your proportions are th8p5-yg lgo:e;m2q 7hwrrkdr) e same as those in Table 7–1, and calculate the mass ofy opgmhqg7d 2 ;lr)rk:8-rwe5 one of your legs.    kg

  Determine the CM of an outstretched arm using Table 7– k6+qnro 5ayfsr2 p5-h1.   % of the person's height along the line from the shoulder to the hand

  Use Table 7–1 to calculate the position of the CM of an arm bent atwj trt9sbuj;1mu /-r :5htmu6 a right angle. Assume that the pw6jb:uu1mh /tjstm 9rur5;-t erson is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in,9qep81f(:cvo5pqlyr +l uhl 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 will be. Will this CM be outside the bo1p9+ql5eyl hrv(q:pfl o cu8 ,dy? Use Table 7–1.

The masses of the Earec+7nhjv0 r4gsqyp, j1k 1b2pth and Moon 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?

  A 55-kg woman and an 80-kg man stand 10.0 m apart on frictionless ice.my -7z l* qpve4s5)(j)iqstyu
(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

  A mallet consists of a i /p:wy8awgf5 uniform cylindrical head of mass 2.00 kg and a diameter 0.0800 m mounted on a uniform 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 8g5: ww/fyapifollow a parabolic trajectory?    cm

  A mallet consists of a uniform is+;- v(-hbtfn4by hru2 )kik cylindrical head of mass 2.00 kg and a diameter 0.0800 m mounted on a uniform 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 b --f nr+4iyvh(sk;btb2hk)uiottom of the handle is the point that will follow a parabolic trajectory?    d    d

  (a) Suppose that in Exam0avdke/;3le u l5 se)hple 7–14 (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

A helium balloon and its gondola, of mass M, are in the(tuya10;ftb* )wyyr e* 5myfg 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. bm rue)wf (g0a1tyy** 5; tyyfWith what speed and direction (relative to Earth) does the balloon then move? What happens if the passenger stops?

  An 0.145-kg baseball pitched horizontally at strikes a ;dhj jk vei137g )gj+rbat and is popped straight up to a height of 55.6 m. If the contact time is 1.4 ms, calculate the averagek37h)+id;1jv grj gje force on the ball during the contact.    $^{\circ} $

  A rocket of mass m traveling wrn88nfa q640efpf 6 inith 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'$_y$=    $v_0$

A novice pool player is fa;(p)czvi m fj2ced with the corner pocket shot shown in Fig. 7–43. Relative dimensions are also shown. Should the player be worried about thp z(vji2)mcf;is being a “scratch shot,” in which the cue ball will also fall into a pocket? Give details.

  A 140-kg astronaut (including space suit) acquires a speed of 2.5m/s by pushing c8gb u8c b (q+myz-6j+3wwty coff with his legs from an 1800-kg spacecg8ybtz +6jbw8(c +wu -qm3cy 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

  Two astronauts, one of mass 6 *qg5 em0esj3bk ws2+ fcsl07t0 kg and the other 80 kg, are initially at rest in outer space. They then push each other apart. How far apart are they when the lighter astronaumcf2 e t0+0k3q 75sejgs w*lsbt has moved 12 m?    m

  A ball of mass m makes a head-on elastic collib *fmp+5;ye5ym8uvh8j,70 zqicc uowsion with a second ball (at rest) and rebounds in the opposite direction with a speed equal to one-fourth its original speed. What is the mass ; q8+vpy,im55 jo*7eymfwbc0zuuc8hof the second ball? $m_B$ =    $m_A$(Round to two decimal places)

  You have been hired as an expert witness in a court case involving an automobix 9snqgkyz 2(4le 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 kixqk92(4gsn yz netic friction between the locked wheels and the 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

A golf ball rolls off the top of a dp)*zgyt pl/) ezbx/t5k88h oflight of concrete steps of total vertical height 4.00 m. The ball hits four times on the wayd xt8t oy/*e p5)/8l zkhbgzp) 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 ball reaches the bottom of the stairs?

  A bullet is fired vertically into a 1.40-kg block of wood at rest directly 8t4 i+k. kvcraz+9rbhq ne;o.above it. If the bullet has a mass of 29h 8zk9+b4 cvi o;tqr.rk+.e na.0 g and a speed of 510m/s how high will the block rise after the bullet becomes embedded in it?    m

  A 25-g bullet strikes and becomes embedded in a 1.35-kg block of wood pl wl3lv j66p, *cdip3 0l6ouoduaced on a hj6ud33io po l0lpw,*u cdl 66vorizontal 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 block a distance of 9.5 m before it comes to rest, what was the muzzle speed of the bullet?    m/s

  Two people, one of mass 75 kg and the otheygq n0p/aw*pwd;by51-6 hwjsr of mass 60 kg, sit in a rowboat of mass 80 kg. With the boat initially at rest, the two people, who have been sitting at opposite ends o yshp65 y wjg -wwda1;bq*n0/pf 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)

  A meteor whose mass was abo7lq8kfk(4 oye1hg 3 rout $ 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

  An object at rest is suddenly broken apart into two fragments by amvof+3;y 2sov k*i8e wn explosion. One fragment acquires twice the s3wekvofim * ;yv2+o8 kinetic energy of the other. What is the ratio of their masses?   

  The force on a bullet is given by the formula 17jf24tgv2b4 cb fy af :ln,flF = 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

  Two balls, of masses nvm 7v2 udel/vg9o6(m$m_A$ = 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

  An atomic nucleus at rest decays radioactively into hay a0 le/./pgan alpha particle and a smaller nucleus. What w/ leyh/a.pa g0ill be the speed of this recoiling nucleus 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

  A 0.25-kg skeet (clay target)k*(.t6u jxb) mnimfhex6 v79n is fired 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? $\approx$   

  A block of mass m=2.2kg so a z4i. uoel8+urnx(e7r aw0.lides down 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.)

  In Problem 79 (Fig. 7–46), what is the /xxgva k0-ls*-0ku;v y+tx czupper limit on mass m if it is to rebound frxv0- ysx lut/ k0gzxck+v;-a *om M, slide up the incline, stop, slide down the incline, and collide with M again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slingshot effect. Figure 7–47 shows the pla1tfwqy0 f) k4enet Saturn moving in the negati4f)1wky0e qtfve x direction at its orbital speed (with respect to the 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