We claim that momentum is conserved, yet most moving objects eventuac9z7-4k9g, pv vqqjst lly slow down and9vjkqqsvp7 9 zgct ,4- stop. Explain.

When a person jumps from mb qfxnm 3d;(:a tree to the ground, what happens to the momentum of the person upon striking the gmb nfd:;x (q3mround?

When you release an inflated bj mu*3fa (ooj4ut untied balloon, why does it fly across the room4m*3uaj(oo jf ?

It is said that in ancient times a rich man with a bag of gold coins froze top:rve(u y(; ey 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 save himself had he not been (e:y reyv;u(p so miserly?

How can a rocket change direction whe c/4lj: - s-f,xj c-ldsn,nvyrn it is far out in space and is essentially in : ,dljlfx/ cn,js rscnvy--- 4a vacuum?

According to Eq. 7–5, the longer the5;w0*mezjp s i impact time of an impulse, the smaller the force can be for the same momentum change, and hence the smaller the deformation of the object on which the force acts.e*pwszjm5 0;i 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 possible to withstand collisnmli.pts+shhi, 2 (kh m-4l( sions. Today, though, cars are designed to have “crumple zones” that collapse upon impact. What ni+stmks.h4(l( l, h2h si mp-is the advantage of this new design?

Why can a batter hit a pitched bad;4o96r 0i8u9.o/ feefme guxcw pad *seball further than a ball tossed in the air by the battee*/ew.dgc9mrpfeod 0 f4io8 x u;ua96r?

Is it possible for an object to ruwn8iw xgs6z;a-r:pgewmj+ (i 2d40 f eceive a larger impulse from a small force than from a lar8ggxm(dnzs4wwi0j w;ui- +fe2a 6: prge force? Explain.

A light object and a heavy object have the sa1 uf 9 (x7hgk7qia;fefme kinetic energy. Which has the greater mome(haf7f17iegufq 9 x;kntum? Explain.

Describe a collision in whim0-unr65m ys nch all kinetic energy is lost.

At a hydroelectric power plant, water is directed a(g2uiq h wj+wdf;. :utt high speed against turbine blades on an axle that turns an electric generator. For maximum power generation, shwiu fhdq+tw (.u;g2j: ould 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 q5p/mj+, hvk 27fj gxfwall at a 45 $^{\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 Earfo-d1qu sqj .75/ tuapth), 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 w uq.5ajq-tf1psu/o d7hat 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 carrying a heavy load in yo- d(3vqt6y0u)hhb:fwvea. d fur arms?

Why is the CM of a 1-m length of pipe at its mid-point, whereas this is jo dj81peeq2:t j.fma mj ubt7l-w::5not true for your arm o827:j mp.dt lbja1 ::5w jeft-meuqj or leg?

Show on a diagram how your CM shifts wy js2+ 1l0 kvqlk4cn4jwv.)mhhen you change from a lying position to a sitting pos.10shkwmyjv2+l jq n44kl)c vition.

If only an external force can change the momentum of the center of mass ofnbc 0/ak-l*yr an object, how can the internal foar -/0*cbnlk yrce of an engine accelerate a car?

A rocket following a parabolic path through thgrp;mz gu,w/ a:z 1oz0e air suddenly explodes into many pieces. What can you say about twg:;puz,z1 mg a/rz 0ohe motion of this system of pieces?

  What is the magnitude o/e+.no,kkuepjw i +a2 f the momentum of a 28-g sparrow flying with a speed of 8.4 m/s oe /k+u2,p+kan.ew ij    $kg\;m/s$

  A constant friction force of 25 N aq-:eq1bltd8uc9v1;.vtjy. 4fwywvx cts on a 65-kg skier for 20 s. What is the skier’wvty:j9 vqqfy4 xcut11 8;wv. .leb-ds change in velocity?    m/s

  A 0.145-kg baseball pitched at 39 m/s,d; qvm(-91am h0zrl kynr7+ka * fmmn is hit on a horizontal line drive straight back toward the pitcher at 52m/s If the contact k10mh*m f r(a;m 9n zkamd7v+n,yrl-q 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 out horizontally with a speed of .9dr jk -j/ /ze63oh y:qz0uda:hhy zl10 m/s Fig. below Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 26.0 kg, and dhhy q 3joj-.9hkr/:0zl/ za zy:d6u ethat of the boat is 45.0 kg. Ignore water resistance. The velocity of the boat is    m/s

  Calculate the force exiulv w n3e3zp:e1ql; 2erted on a rocket, given that the propelling gases are expelled at a rate w13:vnleiq2;u3p lez 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 touchdown isbwc k7q;v up4vjyf,: 2 tackled from behind. When he was tackled by ank,qypvc ufv7:4;2j b w 85-kg cornerback running at 5.5m/s in the same direction, what was their mutual speed immediately after the tackle?    m/s

  A 12,600-kg railroad car travels alone on alevel frictionless t2as*a /yq*+ )bbfpqyjrack 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 ne*) /q + qybpb2ajaysf*w speed?    m/s

  A 9300-kg boxcar traveling at 15m/s strikes a second boxcar at rest. Tiat eu.h1a 5; )wrdsshm *n9*uhe two stick togetm;. a s)19i*ws d uenuhr*at5hher and move off with a speed of 6m/s What is the mass of the second car?    m/s

  During a Chicago storm, wibe+yhyev5:-krzen1 7 nds can whip horizontally at speeds of 100km/h If the air strikes a person at the rate +75ee-v yeb1nh:r k yzof 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 speed of 8.6m/s on zl)ahd 4wf40ra level track. Snow begins to fall vertically and filwr4a fl4 d)0hzls the car at a rate 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 the dire w)ni-8 7wufmaction of its velocity, and the remaining nucleus slows to 350m/snu w-am i8)fw7 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 ej;j+i2jluy*41(cmz0qunhj nl ;v ,tzmerges cleanly at 170m/s If the block is stationary on a frictionless surface when hit, how fast does it move after the bull,cly1u0; jjnzijqj+;nl*(zh4utmv 2et emerges?    m/s

  A 975-kg two-stage rocket is tr6*0wmgs0 dcahard,pveh .7b3aveling 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 is traveling in outer space wit-y)c:r vncqbs 3a s:9bh a velocity of 115m/s To alter brqcs-9): bv3y asc:nits 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 lyb g7ij6a+dcyc c )efp ,(7o2hit off the tee at a speed of 45m/s The golf club was in contact with theilyo( jc7y6f2,p)gc7cbed +a 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 0+kk+ lk q fbibet/4;pnail at a velocity of 8.5m/s and comes to rest in a time interval of 8.0+/ iqk 0kbktebl4 ;fp+ 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=0.06kg and--w)o;2nj l)j mkq66vbttk a y 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 crashworthiness of new automobile +bfa)yj 4pg-cks:i+lmodels. Cars are tested by smashing them into fixed, massive barriers at 50km/h (30 mph). A +:ays4+jp )kbgfic -lnew model of mass 1500 kg takes 0.15 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 ath pssu gl*-f2b vg6*f: 4m/s to the east and is stopped in 0.75 s by a head-on tackle by a tasbvusfgf6 g*-:p lh* 2ckler 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 (masiickq/lp)h9+lri du; s pu;11s 0.060 kg) points in the +x direction and is given 11isik;) i u +;c9purllqph d/by the graph 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 juyblsb pkrby zwtw;js+2.5 )sz,9 h 31nmp 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 thhb. s2lwjy1w5ztz3 )+s y9;pbr,kbn se 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, ye h8-zsy lp+xt-5gn kg moving 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 ball after the collision?Let A represent the 0.440-kg ball, and B sz gp+lhexy,n-yt -58represent 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-oji1a7h9a*tg u m5i:be n collision with a 0.900-kg puck initiallye *75ji9h tia1m:u agb 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 el f iuq*e(w,8i tr m1dpatxjnqi -0+,8lastic head-on collision. If one ball’s initial speed was 2m/s and the other’s was 3m/s in the opposite direction, what will be their speeds after the collision?(Let A represent the ball moving at 2.00 m/s, and call that direction the positive direction.Let B represent the ball moving at 3.00 mf,(ea8ixi r, nd-qqt+j1it* u m0w 8lp/s in the opposite direction. ) v'$_A$ =    m/s v'$_B$ =    m/s

  A 0.060-kg tennis ball, mh; 4 yhx-;shrgoving 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 -hgsh4rh;y x;the speed and direction of each ball after the collision?(Let A represent the 0.060-kg tennis ball, and let B represent the 0.090-kg ball.)v'$_A$ =    m/s v'$_B$ =    m/s

  A softball of mass 0.220 kg that is moving with a speed o p yznp4e,3-d/ah(kno f 8.5m/s collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backward with a speed of 3.7mh /dkpn( po 3ny,z4-ea/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 amusementu 7h- 6smor-*hfl4r rc park 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 ato7-6 4-fhrc*s rmrulh 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 o71pl/w;w 4 f2zmhnpi head-on collision with a second ball initially at rest. The second ball moves off with half the original speed of the 4pm12wofn lh7w i ;pz/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 ck up)13(* y (ev+cnzegkjl4 abube slides down a frictionless 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 90 cm off the floor, where does each cube land? [Hint:(kpn1yujca(3e* b glvk) e4z+ Both leave the incline moving horizontally.]$\Delta x_{m}$$\approx$    m $\Delta x_{M}$$\approx$    m

ake the general case of a4l bh9-wzr tgu6gwh-4jo (*qan 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 d o3 kd *,fd(hdpcrw+7a maximum height h of the pendulum equal to 2.6 cm. A second projectile causes the the pendulum to swing twice as hi (cpfh+7,d *kd3dwdr ogh, $h_2=5.2\mathrm{cm}$ 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 t)4.v)m m vv)zrx wzd.xraveling 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. Determin4 )xxd zwzmvv)mrv.) .e the vertical and horizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formula for the fraction oo;8ec ,fw1e93 mn+m7d 2wrtm2oobw h pf 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 an obje .ut 3qfvq/f6y-mp4vr hz(0n (0gde nect, initially at rest, into two pieces, one of which has 1.5 n( .mf/ehq6z d- (gvqpt0fr4vy0 nue3 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 particle. ) KE'$_A$ =    J KE$_B$ =    J

  A 920-kg sports car collides into the rear end of a 2300-kg SUV stoppedc eb /v;pu(ah: 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, ( cev;:uh/ pabcalculates 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 height of 1.50 m and rebounds to a height of 1.20 rpv.ou:c5h; k) zlx+bqq+ w-x m. Approximately how many rebounds will the ball macvq5krpx ozwl+- )q:uh;x+b.ke before losing 90% of its energy?   

A measure of inelasticity in a head-on collision of two objects is ths2,5 uwpv dut1e coefficient of rdutw25 us v1,pestitution, 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 pie ph;/ uhd24.uxlzo8gyces, one with three times the mass of the other. A depression is made in both faces of the cut, so that a firecracker can be placed in it with the block reassembled. The reassembled block is set on a rough-surfaced table, and the fuse is lit. When the firecracker explodes, the two blocks separate and slide apart. What is the ratio of distances each block. 2hg;po/ huy8ul zdx4 travels? ----待选择----1/91/101/81/6 

  A 15.0-kg object moving in the +x4rm- wwauxs;v k ibj.lhxs3 h8k0d(262rk5m k direction at 5.5m/s collides head-on with a 10.0-kg objec bhu56k wxrs2l m48w r;s xik(3hjm2a d-v.k0kt moving in the -x direction at 4m/s Find the final velocity of each mass if:
(a) the objects stick together;   m/s
(b) the collision is elastic; v'$_A$ =    m/s v'$_B$ =    m/s
(c) the 15.0-kg object is at rest after the collision;   m/s ----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 resta5ar:a4a 0jez5 q iau2 decays into a second nucleus, an electron, and a neutrino. The euq2erzaa5j:ai 450aalectron 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 mas 0f ob1ctzba;sxvg8.60 a1zx js $m_\mathrm{A}=0.400$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 objects of equal mass, eap 8+co-9hzn4 9liu , mxhd9aglz2,m ufch having initial speed the two +m gd u,lhm8zoz,c9-4f9ih xunapl29 move off together with speed v/3 What was the angle between their initial directions?    $^{\circ} $

  Two billiard balls of equal mass mov txnkp q99cne hiztko42(+z78e 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 movingz+px chk(k2 tn98q 4onezt7 9i 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 atom2huby2lpcdtcr *u;+: at rest. After the impact, p:+yt2rucc*2b dl;h uthe 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 perfectly elasnq-2g gvgh5av98t 0t atic collision with another atom at rest. After the 5 ngh0vgq8gta9v2-ta 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. 7–38. Sp yk8+pdx/s fm6gwn- b:ecify relative to the left-hand 1.00-kg n- sd+/w:k x 6fmgpb8ymass.    m

  The distance between asz/dc9 5h* ps*gzuv:fn79ds i carbon atom ($m_{\mathrm{C}}=12\mathrm{u}$) and an oxygen atom ($m_{\mathrm{O}}=16\mathrm{u}$) in the CO molecule is $1.13\times10^{-10}$m How far from the carbon atom is the center of mass of the molecule?    $\times10^{-11}$m

  The CM of an empty 1050-kg car is 2.50 m behind t+mef68+ou wphhe front of the car. How far from the front of the car will the CM be when two people sit6efo +8wm+up h 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 person has a mass of 70.0 kg.    m

  A square uniform raft, 18g wa-)e o.ko,t m by 18 m, of mass 6800 kg, is used as a ferryboat. If three cars, eac,ew. og -kt)aoh 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 side 6qy-a:i5pcnfs $l_0$,$2l_0$, 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 idwip,.b 5ie5ezentical 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 u.pwezii ,eb 55p the load without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l

  A uniform circular plate .t xnooli7 /(ds xs1+gof radius 2R has a circular hole of radius R cut out of it. The center of the smaller circle is a distance 0.80R from the center i xxso(dsn + l/tg1o7.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 proportion q8qjuwhc0) pgmis 6(e.+a,yys are the same as those in Table 7–1, and calculate the mass of one of your legw)qpusma +8i0c.6jyg,h(yq es.    kg

  Determine the CM of an outstretched a d zfml1,;x)dsrm using 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 o y f8 s: :4o1fk97nqq(dhgblgthe CM of an arm bent at a right angle. Assume that t fn1o4g(8 q7fkgy : :q9sbohldhe person is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in a position such that his arms and legs are hanging vert 8l4 pzi;mh(e2 turns/d3r-pyically, and his trunk and head are horizontal, calculate how far below the torso2dr4 (ilh 3;umpp8ntr yez s-/’s median line the CM will be. Will this CM be outside the body? Use Table 7–1.

The masses of the Earth and Mou 7ce1kl1h8bnlwkb* 3on 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 a94:mjo,rmywccb* k 510.0 m apart on frictionless 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 unifo3p w aihud2ssr x 1 q6+eura7(r9:hz,erm 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 tosseqd, (h pa91:eiza2 sx+wu 6se3h rru7rd, 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 ma+yas f,ij..htznw 0g;ss 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 thizw i+ng0s,.h.fj;yta s 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 Exam)ees;t h0u+b qk91v lt- ipy(rple 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 air and stationary , /ayanx )1qfkwith respect to the ground. A passenger, of mass m, then climbs out and slides dk1)/y aanx ,qfown a rope with speed measured 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 poy o-.pz(hsyum6,bi 6m pped straight up to a heiyi- . (sop6z6umyhbm,ght of 55.6 m. If the contact time is 1.4 ms, calculate the average force on the ball during the contact.    $^{\circ} $

  A rocket of mass m traveling with pqz-fa-.am +kspeed $v_0$ 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 wilhh -7+r(ce(ptd*obmth the corner pocket shot shown in Fig. 7–43. Relative dimensions arhp+7moh r -ce(dtl*(be also shown. Should 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 speed of 2.5m/s h*pnm 6o.cyyc ,6apl,:ce t-yby pushing off with,ect ym.op:panc-*h6y6 ,cly his legs from 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 other 80 kg, are initiallydr k38 to rbhry /e)+7zfa rt,bxnl, :,(wth9k at rest in outer space. They then push each other apart. How far apatk )9,r o+l,bdhne3rbtkrfr8y7t h z:a( w/x, rt are they when the lighter astronaut has moved 12 m?    m

  A ball of mass m makes a head-on eew::-ltc.evp p .1 lyklastic collision with a second ball (at rest) and rebounds in the opposite direction with a speed equal to t:wellyk.-:.p vep1c 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 automofasmk wv,m0:: b/vyz3eqh, ) bbile accident. The accident involved car A of mass 1900 kg which crashed into stationary car B of mass 1100 kg. The a ,sf qw)vmhem0:z /b,y kb3v: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. 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 flight of concrete steps of total vf4dcl.o+3m,md oql+y ertical height 4.00 m. The ball hits four times on the way down, 4 d+l f+y.,m3dolomqc 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 (b/;rs bfxt * z1c5wuldirectly above it. If the bullet has a mass of 29.0 g and a speed of 510m/s rfbwx1;ls(cbu5/ *zthow high will the block rise after the bullet becomes embedded in it?    m

  A 25-g bullet strikes and becomes eg cch m 0s2vk5rff;l 5,3fb39nykump0mbedded in a 1.35-kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.25, and the impact drives the block a distance of 9.5 m before it comes to re 3c9fcbp m2 k,m0n 5u;sgfkyhl30 5rvfst, what was the muzzle speed of the bullet?    m/s

  Two people, one of mass 75 kg and the other of mass 60 kg, sit in a r 8p7qx0 ,u(bfmujok(i owboat of mass 80 kg. With the boat initially at rest, the two people, who have been sitting at opposite ends of t8,x( uj kqmf0i7op(u bhe 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 2 dt59 btnni+habout $ 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 b hl+su7x9k hn9y an explosion. One fragment acquires twice the kinetic energy of the other. What is the ratio of their masss9hk 9hnlux 7+es?   

  The force on a bullet ilr9i5x yr*l)e3: agfks given 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 masses :.znyllmr.. y$m_A$ = 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 alphidu)4 pgr4 -zra particle and a smaller nucleus. What wilg4ri4 p-z)rud l 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) is fired at r1r8rm0 qm2yc-2ckcs8*zt rw 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. ola yf.,gx;z22kg slides 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 th4de;2rqb/ 5+mnmbp y6qz*hjyu dhs.6e upper limit on mass m if it is to rebound from M, slide up the incline, stop, slide down the incline, and collide with sj4mmh +* 5d bbqr u ./6;yndz2h6qpeyM again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slingshot effect. Figure c5g 9ey+2yx9. xtmdlms-n1il7–47 shows the planet Saturn moving in the negative x direction at its orbital speed (with respect to the Sun) of 9.6km/s The mass of Satc sgxyxln. 5lm9y+9te21 d-m iurn 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