We claim that momentum is conbx 96ic62/ns 5ijnx snp2f +vn+ gc/ytserved, yet most moving objects eventually slow down and st+ tbjsnsn+c5 piy66x/ n 2n9/vfig2xcop. Explain.

When a person jumps from a tree to the ground, what happens j fs o8q 3uag4rebt-y ;:(7mckto the momentum of the person upon striking the groun-4k3q(jc7oa 8s fb;rt:e gumy d?

When you release an inflated but untied balloon, why does it fly across the roomgz 3,yp ui2qdeb8ri;8ad() rb?eyg3)ri2( rbbqiu,;dp88 zad

It is said that in ancient times a rich man with a bag of gold coins kb9h27l n:qqqfroze 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 save himself had he not been so miserly:ql9q nk bq72h?

How can a rocket change direction when it is far out in s d8j+-. 9xn6ic.cpc4soczgpt pace and is essentially i8 cz-xnctc4c+d9i ppjg.6o.sn a vacuum?

According to Eq. 7–5, the longer the impact time of an cs 6a/c-njay 4m7r6uwimpulse, the smaller the force c-ys w cnr7j c6maa4/6uan 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 possible to nk+g3 cm.1 jfawithstand collisions. Today, though, cars are designed to have “crumple zones” that collapse upon impact. What is the advan+ kg13fcaj m.ntage of this new design?

Why can a batter hit a pitched baseball further than a ball tossed pfhm*/7 +u74lu dhdcz in the air by the bd uzm 7fldhhpc7+*u4 /atter?

Is it possible for an object to receive ahdpnh5v sp(-;v 21 qop larger impulse from a small force than from a large force? hqp(vd; o5pnhsv -p12 Explain.

A light object and a heavy object hms9r q fus7f c,*5+ewuave the same kinetic energy. Which has the greamrs 5u fuqw7+9*ecs,fter momentum? Explain.

Describe a collision in which all kinetic energy is lv5 vctst2:2zrlr0sc sf2h3k8 ost.

At a hydroelectric power plant, water is directed at higs ;t ;doyavl+j1fj 7a0h speed against turbine blades on an axle that turns an electric generator. For maximum power generation, should the turbine blades be designys; ao7d vtfj+ja; l10ed 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 0z y,q(u :hmwzy6nqv 7 gf, mx3ah*l6y$^{\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 (4rqmtr/v72 pmfixed 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 process is momentum con rmrvp/4 7qt2mserved? (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 heavh z xs7zrm..ymg8t6rz :t /a(e0gl/bb y load in your arms?

Why is the CM of a 1-m length of pipe at its mid-0 g*:rwd ) 1nnsua,)pstm;jtlpoint, whereas this is not true for your awjsagd10n,;su)n ltr t mp*:)rm or leg?

Show on a diagram how your CM xy+xd58-o j fushifts when you change from a lying position to a sittiu+o fj5y 8-xdxng position.

If only an external force can change theb 1/ex8baq 6t1t,g, gnnk tok+ momentum of the center of mass of an objecg a/o1t6t x+,1nkntk b,8 begqt, how can the internal force of an engine accelerate a car?

A rocket following a par,qbj:-u5v4gl g/ts m xabolic path through the air suddenly explodes into many pieces. What can you say about the motion of thvtu4,q-5:bxg / slmjg is system of pieces?

  What is the magnitude of the momentum of a 28 8zfxc tb9lp)gl5 ,u)s-g sparrow flying with a speed of 8.4 m/s59 gztu 8)clf, sbl)xp    $kg\;m/s$

  A constant friction force j6s*;uw ;i5d;ecktejof 25 N acts on a 65-kg skier for 20 s. What is the skier’s uec6k;tw;ds5 ;e*ijj change in velocity?    m/s

  A 0.145-kg baseball pitched at 6 1 jhzbev.6r1 p(cjhx39 m/s is hit on a horizontal line drive straight back toward the pitcher at 52m/s I(vh11ez6 xjpjc6b .rhf 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 6.40-kg package out horizontally with a spjpoar/teala; f ymujx. o*; 9zt5/7q5eed of 10 m/s Fig. below Calculate the velocity of the boat immediately after, assuming it was initially at rest. The mass of the child is 2u;z/l totxyap/ me ;j5rfoj5a .9 *aq76.0 kg, and that of the boat is 45.0 kg. Ignore water resistance. The velocity of the boat is    m/s

  Calculate the force exerted on a rock.8u, wn0x+fd k4clrhaet, given that the propelling gases are expelled at rk a +4,fhxu08clwn. da rate of 1500kg/s with a speed of $ 4\times10^{4 }$ (at the moment of takeoff).$a\times10^7$ N a =   

  A 95-kg halfback moving at 4.1m/s ou:08p f6h/ hsrnewibzb, ejg 87ij twv)3sf. :n an apparent breakaway for a touchdown is tackled from behw vewhj:r8fis,:/6bbu.z7g 38) f nthisepj0ind. When he was tackled by an 85-kg cornerback running at 5.5m/s in the same direction, what was their mutual speed immediately after the tackle?    m/s

  A 12,600-kg railroad car travels alone on alevel frictionless 2orw.daynd tg* ., my2track 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 nod.2tmy .d, a2*nywgrew speed?    m/s

  A 9300-kg boxcar trax/*fabc ; s4wyveling at 15m/s strikes a second boxcar at rest. The two stick together and move off with a speed of 6m/ asw/y*c;fbx 4s What is the mass of the second car?    m/s

  During a Chicago storm, winds can pzx(v4 j0xk/uwhip horizontally at speeds of 100km/h If the x( pvk uzj4x0/air strikes a person at the rate of 40kg/s per square meter and is brought to rest, estimate the force of the wind on a person. Assume the person is 1.50 m high and 0.50 m 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 g mx*u,s /.vz(utax ,7ojrq,uof 8.6m/s on a level track. Snow begins to fall vertically and fills the car at a rate of 3.5kg/min Ignoring ag( u,u, 7x* tjq.ouvmr/zs,xfriction with the tracks, what is the speed of the car after 90.0 min?$\approx$    m/s

  An atomic nucleus initially moving zw w5z7jo, l;lat 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;w7j zw,zo 5ll 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/s62kgi ew.:8w /ds3et5vavbw s penetrates a 2.0-kg block of wood and emerges cleanly at 170m/s If the t:5w/ee2v w s v.kg63b8ad wsiblock is stationary on a frictionless surface when hit, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket iso ep -vpz-hrin6-9sd) traveling 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 mass4 2son rwxw,lcg+jp,0vznt5* 3180 kg is traveling in outer space with a velocity of 115m/s To alter its coursexlcw p2go +w 0zsn 5t4vr*n,,j 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 i 5qfr,d9i di.os hit off the tee at a speed of 45m/s The golf club was in contact with theiod dqri5f .,9 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/df1 y4nj6 s-hzc6i;6 lkwa k+vo4j9 nvs and comes to rest in a time interval of 8.0js64k9nd+;f64a-lkyv j vo wnh16zi c 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 speed v=25m/s strikes a wars,r ;ne3hkf*ju( ay1ll 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 en* z3o2 bp 747kr .cv)pgzfaurbgineer in charge of the crashworthiness 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 brought to rest. (a) Calculate the average fobp 72 cb v.agr rk3zu7pozf)4*rce 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 and is stih o/ 6cpzy0:./0q lon i po(735ttxm8zzuzvtopped in 0.75 s by a head-tp(z 8o0ziyt/l6 0 vpmnh.z 5/c7o: i3 ouztxqon tackle 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 thl,xr8rp/ pw;qe +x direction anrlp8w /,p; xrqd is given 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 hei8:3r-lr g cvmgght can a 75-kg person jump without breaking the lower leg vrmr -g8g lc:3bone 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 breaking strength (force per unit area) of bone is $170\times10^6\mathrm{~N/m^2}$ and its smallest cross-sectional area is $2.5\times10^{-4}m^2$ [Hint: Do not try this experimentally.]    m

  A ball of mass 0.440 kg moving east (+x direction) with a speed of collides hebw l ms+*s)2lk+lql3wad-on with a 0.220-kg ball at rest. If the collision is perfectly elasm+sklb )+s q*l l2lw3wtic, what will be the speed and direction of each ball after the collision?Let A represent the 0.440-kg ball, and B represent the 0.220-kg ball. $v'_A$    m/s  ----待选择----eastwest  $v'_B$    m/s  ----待选择----eastwest 

  A 0.450-kg ice puck, moving east with a 1fy/gl l,z5wv speed of 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 object after the collision?Llwg y,/v flz15et 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 pergmk66 ic/ddi6 fectly elastic head-on collision. If one ball’s initi6kg m6idc/id6al 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 collik o zx: h3*wl;-ra:iugdes 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 tenni h::irk-*lw x; uagzo3s 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;f2 2gqbjtja;ud(ta ; rrx/h; speed of 8.5m/s collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backward with a speed of 3.7m/s Calculaarg ;2ahjt 2;j(;r qx/d;ft ubte
(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 collide elastically as one approachet9m owb23/m74t c szdxs the other directly from the rear (Fig. 7–34). Car A has a mass of 450 kg and x t4t/ms9ozmwd723 bccar 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-on colli cezqf /3)vaf e0s;wk3sion with a second ball initially at rest. The second ball moves off with half the original speed of the e/ k)33ecfwvs0afqz;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 dowtn gxpy; /h2z6n a frictionless incline as shown in Fig. 7–35, and elastically strikes another ;x 26 yzghp/tncube 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 incline moving horizontally.]$\Delta x_{m}$$\approx$    m $\Delta x_{M}$$\approx$    m

ake the general case of an obekdpl,:2qz pc )o0 sc b nxn1as30y15qject 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 t ytrehsx)b2:b4k :f zj91fpf(-wv0 e 1 results in a maximum height h of the pendulum equal to 2.6 cm. A srs hb42-f:bzy9 je:1xfktp f0tw) e v(econd 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 itsel :z4 ly3ea/7oiftc e(hf in a 3.6-kg pendulum hanging on a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine the vertical and ho3 et a4/ :clfyozi(e7hrizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formulavljd 9;g8rse0wl:ys; 6mf :xz for the fraction 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 an object, ini3k;l,i3 r7x hix w,84-wobrj2wlhmzb tially at rest, into two pieces, one of which has 3boz2jkhix-xr 7mi bhll843, rww;w,1.5 times the mass of the other. If 7500 J were released in the explosion, how much kinetic energy did each piece acquire? (Let A represent the heavier particle, and B represent the lighter particle. ) KE'$_A$ =    J KE$_B$ =    J

  A 920-kg sports car col38pl t5x qqf:mlides into the rear end of a 2300-kg SUV stopped at a red light. The bumpers lock, the brakes are lockedt5 : x8qqpmlf3, 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 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 l/g rgga:k +s3+wgo aaervr fpa:./)3 of 1.20 m. Approximately how many rebounds will the ball make before losing 90% ofv+/ :l s:)ga ao wrfaagp+3r./3grgke its energy?   

A measure of inelasticity in ww3sgoxtyek u 17*7* ja head-on collision of two objects is the coefficient of restitution, e, define7o3su7 *exkgt ww1y* jd 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 ofyb2 b9tos av8no pl ,dyr1t3-* the other. A dabnlrt oy -v32p9*st ,8dyb1 oepression 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 travels? ----待选择----1/91/101/81/6 

  A 15.0-kg object moving in the +x direction at 5.5m/s collides z ijv: ,5w 9oamdxg7m;head-on with a 10.0-j, 7z;95og d:xwaivmmkg object 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 rest decays into a second nucleus, an el.zf ra 4ey lz- ;zg*kwfq5;vf5ectron, and a neutrino. The electron and neutrino are emitted at right angles and have momentar- fl;wf5;e4zf kqv5gaz *y.z 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 masvr(dzqq pch aky+e 2o.y,d *y09tke6 +s $m_\mathrm{A}=0.400$kg moving with speed $\nu_\mathrm{A}=1.80$m/s strikes ball B, initially at rest, of mass $m_\mathrm{B}=0.500$kg As a result of the collision, ball A is deflected off at an angle of 30.0 $^{\circ} $ with a speed $\nu_\mathrm{A}^{\prime}=1.10$m/s (a) Taking the x axis to be the original direction of motion of ball A, write down the equations expressing the conservation of momentum for the components in the x and y directions separately. (b) Solve these equations for the speed v'$_B$ and angle $\theta_{\mathrm{B}}$ of ball B. Do not assume the collision is elastic. $\theta_{\mathrm{B}}$ =    $^{\circ} $ v'$_B$ =    m/s

  After a completely inelastic collision b nx1ys6*dfk 6retween two objects of equal mass, each having initial speed the two move off together with speed v/3 What was the angle between their initial dyns *1kdr6xf 6irections?    $^{\circ} $

  Two billiard balls of equal mass move at rigzr7wu :3:.aoxohse 1h ht angles and meet at the origin of an xy coordinate system. Ball A is moving upward along the y axis at 2m/s and ball B is moving to the right along the x axis with speed 3.7m/s After the7 o o1uz.:awx:h3srh e 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 colliuaw .d2*b 75;b zkokcrsion with another atom at rest. After the impact, the neon atom travels a;cb5k.*2 zuwrk abo7dway 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 wx*0z0mo by:s hith another atom at rest. After the impact, the neon ab0xos mh:0z *ytom 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 mc (pe aj5 fc/j5ht;vr)ass of the three-mass system shown in Fig. 7–38. Specify relativr 5f);j5capcv/t j(ehe to the left-hand 1.00-kg mass.    m

  The distance between a cd gyv94wu ,gx.arbon 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 iks7+ md2ego5u s 2.50 m behind the front of the car. How far from the front of the car will the CM be when two people sit in th+ um5 g7do2kese 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, 18 m by 18 m, of mass 6800 kg, is used a s-fp1wtc b5s,s a ferryboat. If three cars, each of mass 1200 kg, occupy its NE, SE, and SW corners, determine the CM of the loaded ferrtbfp-,scw s1 5yboat.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of sidesso, ., 8 6yo+dbhy v*ths/ lmcot5yx 28fle-wc $l_0$,$2l_0$, and $3l_0$ are placed next to one another (in contact) with their centers along a straight line and the $l=2l_{0}$ cube in the center (Fig. 7–39). What is the position, along this line, of the CM of this system? Assume the cubes are made of the same uniform material. $X_{CM}$ =    $l_0$ from the  ----待选择----leftright  edge of the smallest cube

  A (lightweight) pallet has a load of identical cases of tomato paste (see Fi. b ku4i4ch5esvmi/r, g. 7–40), each of which is a cube of length l. Find the center of gravity in the horizontal plane, so that the cra,smui e.45v/ cirb4khne operator can pick up the load without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l

  A uniform circular plate of radci/hcc1+ir( cius 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 C of the larger circle, Fig. 7–41. What is the position of the center of mass of the plate? [Hint: Try subtraction.] c1 ch i(cc/+ir  R

  Assume that your proportiou8j2re ie42 umns are the same as those in Table 7–1, and calculate the mass of one of your legu2 u4i 82emrejs.    kg

  Determine the CM of an outstretched arm using Tab65j4:qufdzjl+e5cg.u 8i t xkle 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 right j(4v1vo) ,gp vhi-ll(vwkt)b angle. Assume th-j)(w)pvv1lgko l4bth,ivv( at the person is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in a position such thakayn(0k6 6sfdsb 8i.mt his arms and legs are hanging vertically, and his trunk and he(ifaky k. s0s 86dmbn6ad are horizontal, calculate how far below 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 (b5(z ggf1 .fvgi s9uqMoon 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 mb-0/:xpp ibqpmr .hf04t e. ru 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 uniform cylindrical head of mass 2.00 kg6 vlbj3*f9qf cke *hy9 and a diameter 0.0800 m mounted on a uniform cylindrical handle of mass 0.500 kg andc*69eylf *q3fvk9bh j 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 cylindr( 4;vr6)hrevdyu .t m/4dwqyf ical 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 tosse d4wr.d) 4;fvy6uqemrhvty(/ d, 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/ 9*ay/+b ysna rs;upf6:qcje 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 5og0knb6vn z1 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 measured with respect to the balloon. With what speed b1zno6k ng05 vand direction (relative to Earth) does the balloon then move? What happens if the passenger stops?

  An 0.145-kg baseball pitchebpi 0 :yn 5+9ac3f-xjxd8zvy pd horizontally at strikes a bat and is popped straight up to a height of 55.6 m. If the contact time is 1.4 ms, calculate the average force on the bal-:dcyp j35xbyi pxf0n8av z+9l during the contact.    $^{\circ} $

  A rocket of mass m traveling with spen47) td rf b*vy-nqdv8ed $v_0$ 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 :*9jvc z38 zkv1t znhepi ujz qk4,y49corner pocket shot shown in Fig. 7–43. Relative dimensions are also shown. Should the player be worried about this being a “scratch shot,” i,vcz8k3iz4y*4 hukqtj pzj v1z9n:9en which the cue ball will also fall into a pocket? Give details.

  A 140-kg astronaut (including spa a1s9p wr73hbgce suit) acquires a speed of 2.5m/s by pushing off with his legs from an 1800-kg s 7g3a prshbw91pace 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 initial,6ua pghb, b f1/ydp3el2*wh-u m9oucly at rest in outer space. They then push each other apart. How far apart ah*u2bhep owc,f/ u 1d,bm3gyl6upa9 -re they when the lighter astronaut has moved 12 m?    m

  A ball of mass m makes a head-on w 6roop/5 s,deelastic collision with a second ball (at rest) and rebounds in theed6 /, ow5opsr opposite direction with a speed equal to one-fourth its original speed. What is the mass of the second ball? $m_B$ =    $m_A$(Round to two decimal places)

  You have been hired as an expert witness in a court case involving an gjlouojz(+s ka5 / o77automobile 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. Show/kag zu77sl5+ oooj(j 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 9qxp;dh 7nhp9 total vertical height 4.00 m. The ball hits four times on the way down, each time striking the horizontal part of a different step 1.0 m lower. If all collisions are perfectly elastic, what is the bounce height on the fourth bounce when the ball rehdn7xh9;p9qp aches the bottom of the stairs?

  A bullet is fired vertim,tr6 r*9ua0hjd(8czf8 s ,r a0svpuscally into a 1.40-kg block of wood at rest directly above it. If the bullet * pvraf9 (0us8tszd,ar suhjm 0 r68,chas 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 and becomes embedded in a 1.ent(;osypk ja7k4)hg82 i 2 de35-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 rest, what ki g7 n d2)y28hjs4eek( ;poatwas the muzzle speed of the bullet?    m/s

  Two people, one of mass 75 kg and the other of mass 60 k.i:o z/3tcq nr8uool2 g, sit 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 fucri/o:n 2t. looq 83zar 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 about69 ub9ki*tzhx dg x0bov oaz qr.n;849 $ 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 fragmentshnv 9zd 7s4ow( by an explosion. One fragment acquires no7sd (z hw4v9twice the kinetic energy of the other. What is the ratio of their masses?   

  The force on a bullet is given by the fortdz2*g m( bj7omula 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 massesjs+vj/pbv5 9m uu2b/ s; vsd:d+*r abs $m_A$ = 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 radioactiln(8a vtcdm0c3yi/ +yvely into an alpha particle and a smaller nucleus. What will be the speed of this recoilingy(t3ynv 8la0mc/dci + 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 an angle (dtszlkymw3,bq8go7 8v a1g 4of 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 down a 30.05w6v6jcc(/ (hv+u iacz/k v xy $^{\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–-9 js.i:9r 9szxyhxcie9s d;eo m/ )dq46), what is the upper limit on mass m if it is to rebound from M, slide up the incline, stop, sliex e)qs. 9:di ;isj9-rcszd9x 9m/yhode down the incline, and collide with M again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slingshdnestc2bw*/6 4k ml-not effect. Figure 7–47 shows the planet Saturn moving in the negative x direction at its orbital speed (with re-kc2wmn bltn 4/*6sde spect 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