We claim that momentum is conserved, yet most moving objects even i1sxut:5bdpia0; ao7tually slow down and stop. Ex a d;pas 0ibx57ti:o1uplain.

When a person jumps from a tree to the ground, what happewf/ 5b(q5gfnvpd cozp.7xx/ a r8-qt4ns to the momentum of the person upon striking the ground/zq4gf (5wfrp xo cpn /.aqx58 -d7tbv?

When you release an inflated but untied balloon, why does it fly across t v dh67i9u*mtthe roomhtt9d* 6v7u mi?

It is said that in ancient tt0rk-c8a*;bk b z gz m)zn(sr2imes a rich man with a bag of gold coins froze to death while stranded on a frozen lake. Because the ice wr(s b tckz*zm)2n0 -kz8;bragas 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 change direction when it is far out in space and is essentk/t4guw7 m-ggx z/ zn8 cjs22zially in a /g- zzzx/ kgt cwgu728sj24nmvacuum?

According to Eq. 7–5, the longer the impact t/ah:2nqzty 1y ime of an impulse, the smaller the fo2hnazy1:t q/yrce can be for the 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 possifn4ww6b;d 7q kz ve l)*54v6pvxmo v4nble to withstand collisions. Today, though, cars are designed to have “crumple zoneq4v)65z wkln v7m4xfwedv6 * o;4bvn ps” that collapse upon impact. What is the advantage of this new design?

Why can a batter hit a pl9hd-njw u0* b3vzs( bitched baseball further than a ball tossed in the air by the batter?ujhl(3b z 9- db0vwn*s

Is it possible for an object to receive a larger impulse from a small fo oadd: oi:d-1y:rl5slrce than from a larg5 dylr:ld: -i dos:1aoe force? Explain.

A light object and a heavy object have the same9m wjd*xg0rc d pysbd**.;h 4e kinetic energy. Which has the greateg4 d*;ys0wrm.e d *cjhxp*b9dr momentum? Explain.

Describe a collision in which all kinetic energy is losfi2ms, qr1 xa0j;lm, zt.

At a hydroelectric power plant, water is directed at high speed against turb)-3nojxhv2lh6i( u bb ine blades on an axle that turns an electric generator. For maximum power generation, should the turbine blb3bx( 6j o)vuhhln-i 2ades 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 45 skjj4lr8 (-yj w ua/2t$^{\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 on9:09 svzoahdl 3cw u*cto a hard steel plate (fixed to the 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 procesc 9ws3c*9:hl 0vudoa zs 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 ljy29 woub o.)cean backward when carrying a heavy load in your arms?

Why is the CM of a 1-m length of pipe at its mid-point,p1af-6pm5k d rijl*8r whereas this is not true for your a 8r pkd* -rj5im1lfap6rm or leg?

Show on a diagram how your CM shifts when l-6 bng7rr w7rue.u4 h//pqz gyou change from a lying position to a sitting positibh-r/ w6egur4qg/zn u7l7.r p on.

If only an external force can change the momentum of the center ofnozgkur*cupx- 067 pmr w(12 yv:awc 7 mass of an object, how can the intawu67c(pk7: nu1x czrrwv*gm2 p0yo- ernal force of an engine accelerate a car?

A rocket following az o, m1tc3k -n5hh:6eb- bfva+dvpy+f parabolic path through the air suddenly explodes into many pieb h, vh+f+ cfdozy: nma3t16-5-bkpevces. What can you say about the motion of this system of pieces?

  What is the magnitude of the moma .6i8 (kau3kr)sjodmentum of a 28-g sparrow flying with a speed of $8.4 \; m/s$    $kg \; m/s$

  A constant friction force of 25 N acts on a 65-kg skier for 20 s. Whatbj03+ pezugn9 is the skier’s change in pgb0e+9 jzu3nvelocity?    m/s

  A 0.145-kg baseball pitched at 39 m/s hdmq 3 g+qyd9kbo5m 65is hit on a horizontal line drive straight back toward the pitcher at 52m/s If the contact time between bat a+q d9h 5yq3kmmdb5 g6ond 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-kqmtn0;a upicpf2eswz m24s m+( 5r)6g1; nfzd g package out horizontally with a speed of 10 m/s Fig. below Calculate the velocity of the boat immediately aftemnu5nm;e p c6)g (mt0zfis r24 2;fspadq +zw1r, 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

  Calculate the force exerted on a rocket, given that the propelling +7soj+gbmnebcg. ,m l wfr8s 7h7;/brp /5 gdfgases are expelled at a rate of ,pf8/ b/njfm7beg s.7gdrrsg cl h+;5mbo +w7$1500 \; kg/s$ with a speed of $ 4\times10^{4 } \; m/s$ (at the moment of takeoff). F =    $\times 10^7 \; N$

  A 95-kg halfback mov3jj-n djc, vzwa4h o*1ing 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 qi x9a 6f4 m-pg:*fpdotravels alone on alevel frictionless track with a constant speed of 18m/s A 5350-kg load,initially at rest, is dropped onto the car. What will be the car’s new *694m pao:fd iqpxgf-speed?    m/s

  A 9300-kg boxcar tradj16-sbd j y b5er1t6,ff(9p dfn ce(ovp yf;,veling 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 whiyk fg:+6 e2wzby,ra1 hp horizontally at speeds of 100km/h If the air strikes a person at the rate of 40kg/s arf+ wh,yzg21ky 6eb: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 spec8fmji ;/+ xuled 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, what is the speed of the car af;cxijl/ +8ufm ter 90.0 min?$\approx$    m/s

  An atomic nucleus initially moving at 420m/s emits an alpha particle in:2 zuz v,4te*devv3 zb the direction of its v:v,zz ud*ve2ztv3e4 belocity, 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 emitted?    m/s

  A 23-g bullet traveling 230m/s penetrates a 2.0-kg block of wood and emerges c:upui -y2 rg co z+3xa5n0rhvh fse*78leanly at 170m/s If the block is stationar gzr28u5+haihup f:3 s7 *x0-oen cyrvy on a frictionless surface when hit, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket is traveling at a speedky .59 yyynvh2 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 is traveling in outer space with a veuqld-3k 3q( jilocity of 115m/s To alter its course by 35.0 ikq( -qu3l3dj $^{\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 off the tee at a speedtdd)arce:,m2 of 45m/s The golf club was in contact with the ball fod,)ar :etmd c2r $3.5\times10^{-3}$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 q)dslbtk7 bdu( /3n0j8.5m/s and comes to rest in a time interval of 8.0 ms. (a) What is the impulse given to the jdqun)3b7/btsk 0l d(nail?    kg*m/s
(b) What is the average force acting on the nail?    N

  A tennis ball of mass m=0.06kg and speeddc ( y2dzz5o8z 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 crashworthiness of ne*s iar(gjt hy4nf)(k6w 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 s*ih gka ) 6n4t(yfr(j0.15 s from the time of impact until 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 running at 4m/s to the east an v ls.gqp .m2w.s.ic+od is stopped in 0.75 s by a head-on tackle g.2om wc.pliv+ s.s.q by a tackler 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 4 rj6)xnlg09bl *0n iz7of diodirection and is given by the graph of Fig. 7 4fdl)onzgir 9xi067bo 0njl *–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 withou- cy tsmn5vmki62wlm .n.;+brt 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 breaki6 .tnv -csl.i mmnmkry2bw5+;ng 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 movqffc o h:7ntrt.p45m *ing east (+x direction) with a 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 c* mn7.htfor 4q 5t:pfball 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 ofcz4-4i zvj l4y 3m/s has a head-on collision with a 0.900-kg puck initially at rest. Assuming a perfectly elastic collision, what will be the speed and direction of each ov4 lziz4c4- jybject 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 kmfczi er( li as 9(9w1y;:8ixperfectly elastic head-on collision. If one (irsfl :i 8z(1i wkya;em 9c9xball’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 collicm- wj7j h:4gh/azxr (des 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 0.09:7/wgz4 j- c(hjm xarh0-kg ball.)v'$_A$ =    m/s v'$_B$ =    m/s

  A softball of mass 0.220 kg that is moving with a speed of8vz 9jqoiv7f;n 4p mo0 8.5m/s collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces bac0ifpjm8qv9zn ;o74 vokward 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 ride collii,3 ,*q2 otwc; mcexkyct,5ffde elastically as one approaches the other directly from the rear (Fig. 7–34).ceqmc t;ikxo3, 25ff y,t *w,c 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 gi8uz0+tb w:io3bf9 nzud*f4 elastic head-on collision with a second ball initially at rest. The second ball moves off wifizig8 z0:4bubn+ u9w3fd o* tth 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 frictxe: :fy gf4 x( -buhf+-ij7 c5cgjuge9ionless incline as shown 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 9-ujjfyg4-9gf:xe fxe(7u 5gc :bci+h 0 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

ake the general case of an obj 5aux 6.:zco1 is e,bf4fan+doect 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 heigwl)kro :o+frjl 418ywht h of the pendulum equal to wl1lywj+84 )o r rfo:k2.6 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)

  A 28-g rifle bullet traveling 230m/s buries itself in/ 4sezzyi9 q(e a 3.6-kg pendulum hanging on a 2.8-m-long string, which makes the pends y 9ze/qz4(ieulum swing upward in an arc. Determine the vertical and horizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formula for the fraction of kineticx+tok;e. s7ms 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 an object, initially at rest, into two pieces, one aq:m(4 nwjbo/ of which has 1.5 times the mass of the other. If 7500 J were released in the m/qj nwboa:(4 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 of 7zi p/5x fqgdz( i,ee.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 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 s, fizq.de 5xp7 i/(zegports car, and B represent the SUV) $\approx$    m/s

  A ball is dropped from a hs o7)fspu; xjhv8 bo5,eight of 1.50 m and rebounds to a height of 1.20 m. Approximately how m huvsjsopo 8f;,5)xb7 any rebounds will the ball make before losing 90% of its energy?   

A measure of inelasticity in a head-on collision of two objects is the co 96sqi2;b9i hhziaq7refficient of restitutr97 q;iabhzsq2i 9hi 6ion, 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 the4y/ir h2u./gopicj5 s 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 blockj.g/ rsoc 5i y4hupi2/ 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 directionru7nuoe6mgu 0o+o/1n at 5.5m/s collides head-on with a 10.0-kg object moving in the -x direction at 4m/s Find the final velocity of each/mnu+ ng er o7u0u16oo 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 electrg)x k4-u7ckc :ksizd8on, and a neutrino. The electron and neutrino are em7)cu-xi:k k ksc z84gditted 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 mass3fhppk4 1 jp5m $m_\mathrm{A}=0.400$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 oo 53)biblfq(;bs si5 bbjects of equal mass, each havibii)bslo3 q5f bb 5;(sng initial speed the two move off together with speed v/3 What was the angle between their initial directions?    $^{\circ} $

  Two billiard balls of equal bc pr 2ol,f*lt2 dkp8*mass move at right angles and meet at the origin of an xy coordinate sb*,kod22llp r t8fc *pystem. 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 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 b*nb5/ ghp- q q6lloo6rest. After the impact, the neon atom 6 pq/lbo5nlg*qo- hb6 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 perfectly elastic collision with anot(x r lit;x.udxj5w1(9 ;g jcvhher atom at rest. After the impact, the neon atom travr l( ;w g5juxc91(x;.tvijdxhels 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 bjt c; 9smu667sv* huqsystem shown in Fig. 7–38. Specify relative to the left-mu6vu7js ts6c; * qbh9hand 1.00-kg mass.    m

  The distance between a carbon atom (-coqe lktjv ;3xp8x0 ($m_{\mathrm{C}}=12\mathrm{u}$) 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 from 7w t4pj2/sgsnt 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 m47j g/tp2ssw in the back seat 3.90 m from the front? Assume that each person has a mass of 70.0 kg.    m

  A square uniform raft, 18 m by 18 m, v( y5ia vttc- l1 t725xx/uogoof mass 6800 kg, is used as a ferryboat. If three cars, each of mass 1200 kg, occupy itst (2/ yg1 oovt5c5l7t-axxvui NE, SE, and SW corners, determine the CM of the loaded ferryboat.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of side)cy8-p pu1gzn*nm n)bs $l_0$,$2l_0$, 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 o 7i,zrl7 *vsh3ebx2edf 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 crane operator can pick up the loadde ih 3vb7 2x7rle*z,s without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l

  A uniform circular plate of radius 2R has a circular hole of radius R cut out o4f4yuc7a9c; 8oremoc f it. The center of the smaller circle is a distance 0.80R from the center C of the larger circle, Fig. 7–41. What is the positionoeac 4r9;8c yc oufm74 of the center of mass of the plate? [Hint: Try subtraction.]   R

  Assume that your proportions are the same as those in Table 7–1, and ca3*zr0i5 7cmq v 8l b3y/wstuomlculate the mass of one of your l 3r/l57su 83mwi0ycb*motvz q egs.    kg

  Determine the CM of an ok -o jecprvb*:(:-qltutstretched arm using Table 7–1.   % of the person's height along the line from the shoulder to the hand

  Use Table 7–1 to calcbsnj.u l q097 mcx4g+g:0wxwqulate the position of the CM of an arm bent at a right angle. Assumec 70xwgq:l9mwg sjx0 n+. 4qbu that the person is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is i-qfs4hxg +nk may/h/4n 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 wsax- fqkh4/y 4/g+nhmill be. Will this CM be outside the body? Use Table 7–1.

The masses of the Eae n.m 0b 9 lo.+t:tkamgtp,s+yrth 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 frictionlaj6w*w.2++1bhr ;lesmz y p iress 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 diameh/u 3q nb rrwp6g+o-u7rkx*)oter 0.0800 m mounted on a uniform cylindrical hrp-* /ob ku6 whgu7 xonq+3)rrandle 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 head of wq*ug-a+27n uouww( a mass 2.00 kg and a diameter 0.0800 m mo+unu 7g*2wu(-awawq ounted 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 7–1,fb(:4ujd cod8 i ab0v4 (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 maf 1s2cj2*i-7i, ain 11b j crjoxug6noss M, are 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 measurn2 1so j2xcjib au7ig*ij 16rno-1cf,ed with respect to the balloon. With 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 bat and is popped straia0f1sw(e un:z gk 9z;zght up to a height of 55.6 m. If the contact time ise wz: 1an9(fgk uszz;0 1.4 ms, calculate the average force on the ball during the contact.    $^{\circ} $

  A rocket of mass m traveling with eim nhzr9ka+9o: 85ipspeed $v_0$ 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 the va*x3;t: o ix/wkf0 awcorner pocket shot shown in Fig. 7–43. Relative dimensions are also shown. Sha;w o: kxf3va iw/t0*xould the player be worried 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 ngu06v jk43 euspeed of 2.5m/s by pushing off with his legs froevjg 63nu04u km an 1800-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 othe1v/9k* ot8 p7:x hbrg2rg ckmkr 80 kg, are initially at rest in outer spa:txg /89h7bomkrvgpk cr*1k2 ce. They then push each other apart. How far apart are they when the lighter astronaut has moved 12 m?    m

  A ball of mass m makes a head-on elast::3l:w5 fxtwr (:irrzw0 tcc gic collision with a second ball (at rest) and rebounds in the opposite direction :rwrtf: cl5rc i::g 3tx (w0wzwith 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)

  You have been hired as an expert witness in a court case involving an automoh0hd .g1vq2d,a9bdx 6 jgczv u0wix72 bile 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 kinet0hu9g,gvai dxhbj 76wdq 0 v .12xzc2dic 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 85 g mbw(fd+9tf.ak y7pc/ ciua flight of concrete steps of total vertical height 4.0 / 8.t5uff7b9cw (pcmagkid+y0 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 ball reaches the bottom of the stairs?

  A bullet is fired verticazedxcpia,iv ; ;6/g(b lly into a 1.40-kg block of wood at rest directly above it. If the bullet has a mass of 29.0 g and a speed of 510m/s how high will the block rise after the bullet beco/eaxi;(c iz bpd g,;v6mes embedded in it?    m

  A 25-g bullet strikes and becomes embedded in a 1.35-kg block n /a.e8w7fg tiujip*1 ji1ws: 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 0.25pwit 18was ng7ie*1:fj./ui j, 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 mass 60 kg, s t7)-ndpxz8.v) gzdsm it in a rowboat of mass 80 kg. With the boat initially at rest, the two 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 directiox)tg)nvzz .8-7ps dd mn 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 b:s j)x.cbfj 6was 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

  An object at rest is arj:o85rod )jsuddenly broken apart into two fragments by an explosion. One fragment acquires twice the kinetic energy of the other. What is troaj d 5j8:ro)he ratio of their masses?   

  The force on a bullet is given by the formulho0uko7r4a wp w0.i4q a 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 masses 3d qpj,a5l: jy0hz/p.ri n4gz$m_A$ = 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 an al) lz*ljva:u5b 4/pufopha particle and a smaller nucleus. What will be the speed of this recoiling nucleus if the speed of zu 4*u/va5ljp ob:lf) 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) is fired at ;oe6 mmj -puyhtb ,vsi6q .(t1an 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 slides bual+:26k pqq.utk e :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 4)hj ellq nc4*to rebound from M, slide up the incline, stop, slide down lh *4 jcl4q)enthe incline, and collide with M again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slingshot 30odmr lde9c .effect. Figure 7–47 shows the planet Saturn moving in the negative x direction at its orbital speeermcl d.9do03 d (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