We claim that momentum is conserved, yet most moving objects e sutusa )w**):qok8zhln7 kbf yf66q,ventually slow dow o7y8 ,6 wq*n*)ku qbhfuk zsltsa6:f)n and stop. Explain.

When a person jumps from a tree to the ground, what happe o zvip-d2mo*6bhn) (qns to the momentum of the pe*op-hmvqni)b (d6zo 2rson upon striking the ground?

When you release an inflated but untied balloon, why does it flyjbh23 4zd(xog mza3i 2 across the room 2h odz3gia2m3zjb(4 x?

It is said that in ancient times a rich man with q qdk o4hy,q8+a bag of gold coins froze to death while stranded on a frozen lake. Because the ice was frictionless, he could not push himself to shore. What could he have done to +h,y8o q4qqkd save himself had he not been so miserly?

How can a rocket change diz5 ufg*r 5f-czrection when it is far out in space and is essentially in a vacuum?5g-z5ufc *rzf

According to Eq. 7–5,9 /5rs:wu lguou. bi.x the longer the impact time of an impulse, the smaller the force can be for the same momentum cha.gw.u:b5ox uu/l isr9 nge, 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.jvr nqs+ 0b3s as possible to withstand collisions. Today, though, cars are designed to have “crumple zones” that collapse upon impact. What is the advanta rqj b0v3ss.n+ge of this new design?

Why can a batter hit a pitched baseball further tha:m1 gokac+hqw i;r53in a ball tossed in the air by +mcwk a; oq3:5gri1h ithe batter?

Is it possible for an obj:+2;y aoel.wz9 mmkfug4kcr5 ect to receive a larger impulse from a small force than fro.em 5+kr;lkw u za2fy4cg9om:m a large force? Explain.

A light object and a heavy object have the same kinetic enyr. zf .a4f-okergy. Which has the greater4fazyk. r of.- momentum? Explain.

Describe a collision in which all kine :*4-oac9 vxgwq/cybd tic energy is lost.

At a hydroelectric powd 5r s7 oddgoz6r6i:j;er plant, water is directed at high speed against turbine blades 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 wao7r;: 6zisd56o rdjd gter rebounds?

A squash ball hits a wall .vcb19 si6oynd 79sz kat 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?

A Superball is dropped from a height h onto a hard steel plate (fixed to theswqp5 n ml7,g- Earth), from which it rebounds at very nearly 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 tq5-lg ,nw p7mso the steel plate.

Why do you tend to lean backward when -k* i+p*g ktltcarrying a heavy load in your arms?

Why is the CM of a 1-m length of pipe spacih e( 4l7-22tads) fy.a mat its mid-point, whereas this is not true for yohfd .eca)t4l2ss y p(i2maa-7 ur arm or leg?

Show on a diagram how your CM shifts when you c f0l.lkzv/-yh hange from a lying position to a sittin-flk0vh zy/ l.g position.

If only an external force can change the momentum of the center of mass of anb8i- (qs/rb dglnz. t/l+bn; mlth *s5 object, how can the internal force of z(.q5t s*d rn nbli/8t/hllg;b+-bsman engine accelerate a car?

A rocket following a parabolic path through the air suddenly explode5woa j;yl*u+/4sp u:*s ypxzfz9f )nm s into many pieces. What can you say about the motion osslj+um f* :9ny 4x*z/)ywzopa;f p5 uf this system of pieces?

  What is the magnitude of the momentum of a 28- i /+m 0fqoz. irej(gqsc158ovg sparrow flying with a speed of $8.4 \; m/s$    $kg \; m/s$

  A constant friction zrkfiu+.ruya8 1k yc:+ w9lf2 force of 25 N acts on a 65-kg skier for 20 s. What is the skier’s changekf l8f:+ u ariwuryy 1cz9+.k2 in velocity?    m/s

  A 0.145-kg baseball pitched at 39 m/s is hit on a horizontal /kc fc bli450nv 7fb*ms4v.mv line drive straight back tf5bcbvs.mvi*4 fc vk7l4n0m/ oward 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

  A child in a boat throws a c n1 u0ds7-vyp6.40-kg package out horizontally with a speed of 10 m/s Fig. below Calculate the velocity of the boat immediately after, assuming it was initially a n -pd1suy0vc7t 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

  Calculate the force exerted on a rocket, given that ttdi 7 r16 xnydiw vek13tk.bol:/3f0nhe propelling gases are expeix.e01o kv 6i1nw n:d /ttky3d l73rbflled at a rate of $1500 \; kg/s$ with a speed of $ 4\times10^{4 } \; m/s$ (at the moment of takeoff). F =    $\times 10^7 \; N$

  A 95-kg halfback movizieappij1 o jas6a7r -* xb.:*a --qt5f 2jhzing 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?    $m/s$

  A 12,600-kg railroad car travels alonedpu2/9*t* +, wcwyvytysza.n on alevel frictionless track with a constant speed of 18m/s A 5350-kg load,initially at rest, is dropped dwzav*u.p*y t,ty9s n+2/ywc onto the car. What will be the car’s new speed?    m/s

  A 9300-kg boxcar traveli3hur jj; nm89 w/yj25fm(rhyo ng 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?    $m/s$

  During a Chicago storm, winds can whip1i;p csa)r 6dj horizontally 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 on16d pijsr)a ;c 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 speed of 8.6colzr omi32br,h(7g + m/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, what is the spe2brr z+m7gh ( 3o,colied of the car after 90.0 min?$\approx$    m/s

  An atomic nucleus initiai1o:k+dh b. uu (q3pdllly moving at 420m/s emits 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.bphudk31oq+ liu(d : alpha particle have when it is emitted?    m/s

  A 23-g bullet traveling 230m/s penetrates a 2.0-kg block of wood and ebt 1:xfxf(b(.yx- fbl* dyi*cfv aga-eo8b+*merges cleanly at 170m/s If the block is stationary on a frictionless surface when al( 8.(if* yetbbyfbfb xgvadc-*1fo-x*:+xhit, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket is traveling at a speed o3m: ;ppq tz;dhf $5.80\times10^3\mathrm{~m/s}$ 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 is traveling in outer space with a velold agrv9:/ )lb 1lo*,ba5 pohmcity of 115m/s To alter )p9,dola *ahl 5bl /bvg:mro1its 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 0.0.5); txypwv5h0buj5i paj1 b m45 kg is hit off the tee at a speed of 45m/s The golf club wxip5 ; w0a5ptvu hyj51j bb.m)as in contact with the 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 comes to rest in a ti;xl*9on8 1epr d/-ckj v txd+gme interva*vnd/do 8;ge-p1rtc+kl 9 xj xl of 8.0 ms. (a) What is the impulse given to the nail?    kg*m/s
(b) What is the average force acting on the nail?    N

  A tennis ball of mass m=0.06 ah+b/k+qy 4;9vcd,xsbcsfu ;kg 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  ----待选择----leftright 

  You are the design engineer in charge of the crashwort3p:nt+wps hr7hiness 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 until it is brough+r3:shn7 w ptpt 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 running at 4m/s to the:fm c*v52k 5lof2h few east and is stopped in 0.75 s by a head-on tackle by a tackler running due west. Calcu ffwom2ck*hl2fve :55 late
(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 direv;q;jo uo ,3ny0f1bxection and is given by the gr,; x ofbvu0;oyejq n31aph of Fig. 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

  From what maximum height can a 75-kg person jump without b3lyystwva9 xhd0:* 0xreaking the lower leg bone of either leg? Ignore air resistance and assume the CM of the person moves a di h:yta* x0 3vld0xw9systance of 0.60 m from the standing 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

  A ball of mass 0.440 kg moving east (+x direction) with a3s2uxcr -4tzujx7 lqj8d qp1- speed of collides head-on with a 0.220-kg ball at rest. If the collision is perfectly elastic, what will be the speed and direction of each ball after the colllpuudj4 c73 qx1j 2-rs q-ztx8ision?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, mo-1ykps(d0j- je tut:tving east with a speed of 3m/s has a head-on collision with a 0.900-kg puck initially at rest. Assuming a perfectly ek1tjdyt-s-tp 0(u:e jlastic 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 perftfbrdy 5vn; 9m/ xrd.,w+ j9qnectly elastic 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 thyd995;r mdnfn.b w ,rv+jt xq/e 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 bal; acp /)ws08vzi:adqc4m(t hy1ox .eml, 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 rex;(0shiz o1 4w.t vaa8ymedpc )/cm:qpresent the 0.060-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 with a speed of 8.5m/s+-y5vbx6zs mscu4 bb9 collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backw4x6yusc z5 9s b-m+vbbard with 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 ridl: t5)yos34olyh x1xde collide elastically as one approaches the other directl :ld4s5xhotxoy 3)y l1y 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 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

  A 0.280-kg croquet ball makes an elastic head-o)zz : excrez6af, a;,on collision with a second ball initially ae e;ac, zz6z:)ar,oxft 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?   

  In a physics lab, a cube slides down a frictionless incline as sox72bc ,sv2s zhown in Fig. 7–35, 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 does each cube land? [Hint: Both leave the incliozs,7s vx2c2bne moving horizontally.]$\Delta x_{m}$$\approx$    m $\Delta x_{M}$$\approx$    m

ake the general case of an objecte9iw33 - kkdsq/t qz:8*di1yccmq9dq/mqe;u 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(x os ,h)4m+akcv6gig a maximum height h of the pendulum equal to 2.6 cm. A second projectile ca( ohmvgk+c6s ,4xi g)auses 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)

  A 28-g rifle bullet traveling 4q wtlqhx+*ensn5pd kp331n7 230m/s buries itself in a 3.6-kg pendulum hanging on a 2.8-m-long string, which makes the pendulum swing upward in an arc.n n lt3wn4+ q7k3seh5 p1xqdp* Determine the vertical and horizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formula for the frac8482cgd0abgz 9jyn r ution 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

  An internal explosion breaks an9p1pqvypp-)s, l pozv7p/gui/d) skkfx/40g object, initially at rest, into two pieces, one of which has 1.5 times the mass of the other. If 7500 J were r/0 x,gloi ypks d su k)7pp/9z1pf-g)pvq/4pveleased in the explosion, how much kinetic energy did each piece acquire? (Let A represent the heavier particle, and B represent the lighter particle. ) KE'$_A$ =    J KE$_B$ =    J

  A 920-kg sports car collides into the rear end off( -1q. 4s ;uxbosdkrj 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 so j.rdk(q4f ;ux-b1sbefore stopping. The police 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

  A ball is dropped from a heigh62x i*tlx*y(hdowx:p+ tzf )dh h4t, wt of 1.50 m and rebounds to a height of 1.20 m. Approximately how many rebounds will the ball make before losing 90%h2(*6yh d fwxwpld t,t+tixh* oxz)4 : of its energy?   

A measure of inelasticity in a head-on collision of two objects h;/xk) .f.hwpmwbbdj+;p* upis the coefficient of ;) bjhd x+.fw ppmbuwp/.k;h*restitution, e, defined as$e=\frac{\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}}{\nu_\mathrm{B}-\nu_\mathrm{A}},$
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 of the oof pul906 e6rgther. A depression is made in both faces of the cut, so that a firecracker can be placed in it withf66o puleg0r9 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 in the +x direction at 5.5m/s collides head-2d; 7(a voyfna2* *ixtfkx f4z3okdm.on with a 10.0-kg object moving in the -x direction at 4m/s Find the final velocity of eactd*xkn im*xao yf(o;4v3dk 2f2zf a.7h 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 second nucleus, an q-b 25s1f+9qgdhz; s/coua paelectron, and a neutrino. The electron and neutrino are ugbac 2 -;zd9a5sfs/o 1qhpq +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 masst ,x(qzzi9, c(n 5ujql $m_\mathrm{A}=0.400$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 a-lsd k9n 7ac j 9cc-e6bz-p4ycollision between two objects of equal mass, each having initial speed the two move off together with speed v/3 What wasa cp9cab dj s-ez 4cyk9--7n6l the angle between their initial directions?    $^{\circ} $

  Two billiard balls of equal mass move at right angles and meet at tqkbw0vj; 1 tu-he 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. 7–37). What is the final direction of ball A and what are their two speeds? direction of-wu0b; 1 jqktv ball A is  ----待选择----x directionx direction v'$_A$ =    m/s v'$_B$ =    m/s

  A neon atom (m=20u) makes a perfectly elastic collision with another atom at rtt,miw mzesth+ ;+m ,4est. After theet+ihtt mz; + wm,m4,s 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

  A neon atom (m=20u) makes aajgrwcwq * .7zt.s3*v perfectly elastic collision with another atom at rest. .sgrz caj*w37w. *vt qAfter 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 the three-mass system shown in Fig. 7–38si /)rmc- (pa6ca iqx)xroz:4. Specify relative to the left-hand 1.00-kg m s/iqo(a6z4-x)arx)cr :cmi pass.    m

  The distance between a carbon atom ( fl4l/5u s2aoz$m_{\mathrm{C}}=12\mathrm{u}$) 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 behx/-mupv )vh t3ind 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 from the front? Assume that each p/p)v- vu xhtm3erson has a mass of 70.0 kg.    m

  A square uniform raft, 18 m by 18 m hy1ld45ayt w*, of mass 6800 kg, is used as a ferryboat. If three 45*a1dwtl yhy cars, each of mass 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 sidesn2gmpi ( np;9wl y7.or $l_0$,$2l_0$, 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 5xmw p:* b4nila load of identical cases 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 craxb4l wmin 5:p*ne operator can pick up the load without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l

  A uniform circular plate of radius 2R has a etgbvz f8;r;,*ixg55j(rpte circular hole of radius R cut out of it. The center of the smaller circle is a distance 0.80ev,rpi 8 bg(;jz; *rge5ttfx5R 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 th3zo dmqu9 7z5ze same as those in Table 7–1, and calculate the mass of o qz9zd3ozm75u ne of your legs.    kg

  Determine the CM of an outstretched arm using:* vwey3a1 :w8jdcbd;q-yf g k uynk.+ Table 7–1.   % 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 at a /vzfve07mc g9 right angle. Assume thatgc9 / vfz0em7v the person is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is is wg/) vmva.e4n a position such that his arms and legs are hanging vertically, and his trunk and head are horizontal, calculate how far below e4.a gwm/)svv the torso’s median line the CM will be. Will this CM be outside the body? Use Table 7–1.

The masses of the Earth and Moon arg7 3+ueux/lkkp d6g uus5t2.hd ;c e,q*ard y7e $5.98\times10^{24}$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 frictionlesszkv-*iu *f j4x 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

  A mallet consists of a uniform cylindrical head of mass 2.00 kg and a di)+z k5 w6ak47rbkhaxr ameter 0.0800 m mounted on a uniform cylindr74wrkakrhz) b6x5 a+kical 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

  A mallet consists of a uniform cylindrical heaca5/ hs pnn:l)d of mass 2.00 kg and a diameter 0.0nsn/ 5p:a) lhc800 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 follow a parabolic trajectory?    d    d

  (a) Suppose that in Example 7–14myc +zr1z m9*i (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, areu;b* d h.r;* l8xlb6c,tkgdvb in the 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 direction (relative to Earth) does the balloon then move? Wh,lg*uldk; ct*xb vd;bb8 6.rhat happens if the passenger stops?

  An 0.145-kg baseball pitched horizontally at strikes a bat ad30 mi7bx fyey9dh6 s4nd is popped straight up to a height of 55.6 m. If the contact time ishdex94s0y3imf b7 yd6 1.4 ms, calculate the average force on the ball during the contact.    $^{\circ} $

  A rocket of mass m traveling with speedu1n f0 nw qrs12*kidn*kml-uigk+.4z $v_0$ 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 faced with thead t a7z0q5g8z corner pocket shot shown in Fig. 7–43. Relative dimensions are also shown. Should the player be worra az7dgq850t zied about this 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.edid 6v5mv-8 p5m/s by pushing off with his legs from an 1800vdp 6d5iv-em 8-kg space 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 60 kg and the other 80 kg, are initially at rest kik,)4tx v wkkyt6q6vi w6f3-in outer space. They then push each other66xt,i i6vv)4 kwk wfk3q -ytk apart. How far apart are they when the lighter astronaut has moved 12 m?    m

  A ball of mass m makes a head-on e jqcjd;;d;j 15bkmmpswsu (69lastic collision with a second ball (at rest) and rebounds in the opposite direction with a speed equal to one-fourth its original speed. What m5(;u 1bd dk jc;mqj;js9spw 6is the mass of the second ball? $m_B$ =    $m_A$(Round to two decimal places)

  You have been hired as an expert witness in a court /2btr4k ruxi o)qtu)+7p7xc i1nx+rs case involving an automobile 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 the road was measured to be 0.60. Sho rt p7nr+r 1)tioskuc+xq)2ubx4/7xi w 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 flight of conc-/ 8zog 9z wfk gx;e6ct3hay0jrete 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 w-zcefjagy/otk 3xg68h0;9z 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 5 /chfs,bh.m:un lpf )into a 1.40-kg block of wood at rest directly above it. If ths5h cp:nlmf fub )/,.he bullet has a mass of 29.0 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 ajesf1r-hy5e .wzy (0h nd becomes embedded in a 1.35-kg block of wood placed on a horie(5 zf0-jhy.w1hs rey zontal 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 other of ma3 uv 3jr+ fg4o;cafp4css 60 kg, sit in a rowboat of mass 80 kg. With the boat initially at rest, the twov+;ajupg f3f rcc434o 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)

  A meteor whose mass was about f;obg ;lty+b- 3.anz,wws j(y $ 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 5a/mv,b3jfnf+ eezcvz :scvh;93)z b by an explosion. One fra +cv zs az9,ev: 3j3vnbffb)cz;e5/mhgment acquires twice the kinetic energy of the other. What is the ratio of their masses?   

  The force on a bullet is given:0 5j;2cjdjf h k,ainu by the 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

  Two balls, of massespgs264iamt6dyxrs 6z -i+7 ra $m_A$ = 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 r3xi) :xucfhyk1m 60hu/ a:niwn yey z37-n5anest decays radioactively into an alpha particle and a smaller nucleus. What will be the speed of this recn30e5n: wxh7 zicix/ yuh31yn6an mu)-kayf: oiling 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) is3p* )cb2zpmd z 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 ,7l(ztodpby;y, + pa h1ygllqy70 4xxslides 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 upper limit on mass m if it is to rebo(ih c:h k0m,j,cjeh,jund from M, slide up the incline, stop, slide down the (,hj:hc mehk, i0j,cj 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 plaprbbs ;9y2(e k:l ij;cnet Saturn moving in the negative x direction at its orbital speed (with respect to the Sun) of 9.6km/s Tkb9e;(cb2i;sp: yrlj he 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