We claim that momentum is conserved, yet most moving obk;iy/2:y1tmpi sl2 iyjects eventually slow down and 2/pitl i mk2 1:sy;iyystop. Explain.

When a person jumps from a tree to the gjz ou: 8 kr3)*htsce5hround, what happens to the momentum of the person upon striking the ground? 5kchz*ej o sh3u8tr):

When you release an inflated but untied balloon, why does it fly across the ri4..jg bekfx (oom4(b.e . fxgikj?

It is said that in ancient times a 4c-zk7(djlwzdr:3 i brich man with a bag of gold coins froze to death while stranded on a frozen lake. Because dli r:( d4k7c 3wz-jbzthe ice was frictionless, he could not push himself to shore. What could he have done to save himself had he not been so miserly?

How can a rocket change direction when it i li62sqi*kc;h d+un4 : hb2ckjs far out in space and is essentially in a vacchbs24ik:qnjl;6u * 2hik +dc uum?

According to Eq. 7–5, the longer the impact time of an impulse, the smaller 0 zswk6s3jpui.05rb yel11kjma;m 0gthe force 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 dease3;ij swl05 1 mzpy 1kmk6jr.b g00auth.

Cars used to be built as rigid as possible to withstand collisions g;bz /84cced:y d8tzk. Today, though, cars are designed to have “crumple zonet:8; k8y/4cez bdzcdg s” that collapse upon impact. What is the advantage of this new design?

Why can a batter hit a pitched baseball further than a ball tossu95* z) cg7os,c siftwed in the air by the 7 g,w9otu zcfs)ics5* batter?

Is it possible for an object to receive a larger impulse from a small d-g61dp 9eor1)h f0n 4yyvmyq+ wys(z force than fr0hns fzdd 9 6wqo) v4reygpm1+1(y-yyom a large force? Explain.

A light object and a heavy object have the same kinetic yitqw:sg 65ry / g3-smenergy. Which has the greateg56 t:gssi mq3w-yry/r momentum? Explain.

Describe a collision in which all kinetic ehcm6rbl-,f t .nergy is lost.

At a hydroelectric power plant, wattn, tb.qbc( q,7qk6jy er is directed at high speed against turbine blades on an axle that turns an electric generator. For maximum power generation, should the turbine blades be b6 n,kq 7(tbyj,.cqtqdesigned so that the water is brought to a dead stop, or so that the water rebounds?

A squash ball hits a t00q fnrgyi nog: ,9v0bg* o,pwall at a 45 $^{\circ} $ angle as shown in Fig. below. What is the direction (a) of the change in momentum of the ball, (b) of the force on the wall?

A Superball is dropped from a height h onto a hard steel plate (fixed to the E1e80iwz2 yzqa arth), 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 cy2wa0ez ziq1 8onsider the ball and Earth as our system, during what parts of the process is momentum conserved? (c) Answer part (b) for a piece of putty that falls and sticks to the steel plate.

Why do you tend to lean backiazrs 3h9p65i8p mc .h4mm sk-ward when carrying a heavy load in your arms?

Why is the CM of a 1-m length of pipe at its mid-point, whereas this is not tup(/rduu ifp,y k0s.8 h /cu)wrue for your arm or leg? (u/spf,uyw8 ik0p)/ ru dc.hu

Show on a diagram how your CM shifts when you change:1w wyp 96jf;ixnc;ld:pcv ) y from a lying position to a s:;l ywp:y6c1w ) ;vjx9ncpifditting position.

If only an external force can change the momentum of the centtb c:wj8).xcr s1- z0v qj)rwber of mass of an object, how can the internal for )vqszx) c -8bj0bw.trc:r1jw ce of an engine accelerate a car?

A rocket following a parabolic path through the air suddenly explodefg1 0o8.mdw kpzie+o;s into many pieces. What can you say about the motion og1+m ze dkf. ;o08pwiof this system of pieces?

  What is the magnitude of the momentum of a 28-g sparrow flying with a speed o,eqww(k6l hom;pm/ 7 of $8.4 \; m/s$    $kg \; m/s$

  A constant friction force of 25 N acts on a 65-kg skier for 20 s. What is thk.yznofri 7.z8ij9 * me skier’s change i.mi9 7.nz8jzk fyor*i n velocity?    m/s

  A 0.145-kg baseball pitched at 39 m/s is hit on a horizontal line drivio 9fq-u/c-yte straighto f/iqtu- c9y- back toward the pitcher at 52m/s If the contact time between bat and ball is $3\times10^{-3}$s calculate the average force between the ball and bat during contact.    N

  A child in a boat throws a 6.4 fn+/1 mqe2pzx0-kg package out horizontally with a speed of 10 m/s Fig. below x p1mfnq/2+ezCalculate the velocity of the boat immediately after, 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 aommk.b j6 e/ .wkcs34on a rocket, given that the propelling gases are expel kwekb 4mosc/ ja.63.mled at a rate of $1500 \; kg/s$ with a speed of $ 4\times10^{4 } \; m/s$ (at the moment of takeoff). F =    $\times 10^7 \; N$

  A 95-kg halfback moving (ap83x8v 4hvzzbkq x6at $4.1 \; m/s$ on an apparent breakaway for a touchdown is tackled from behind. When he was tackled by an 85-kg cornerback running at $5.5 \; m/s$ in the same direction, what was their mutual speed immediately after the tackle?    $m/s$

  A 12,600-kg railroad car travels alzu ;ygi5pf2j (f;1t nione on alevel frictionless track with a constant speed of 18m/s A 5350-kg load,initially at 2 uy;1tf5pzg(ii ;jfn rest, is dropped onto the car. What will be the car’s new speed?    m/s

  A 9300-kg boxcar traveli)ny 5 r. ki6yedr)*lsi4/uljrng 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, winjf+fo lno, 8u,ds can whip horizontally at speeds of 100km/h If the air strikes a person at the rate of 40kg/s per squ +8fu,foo,nj lare 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 vk:65o l3b)y2hjffd cdt9xwrd2 0ah 3speed 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 afterjx v3khr 3wlf29c b56 :dd2d 0yotfah) 90.0 min?$\approx$    m/s

  An atomic nucleus initia:67fb fzh- kqr dd,8rzlly moving at 420m/s emits an alpha particle in the direction of its velocity, and the remaining nucleus slows to 350m/s If the alpha particle has a mass of 4.0 u and the original nucleus has a mass of 222 u, w hfz76f-dzrbr dq k:8,hat 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 clewe:, x7kym 3(*fqts03w.x+hwr /l y9iqtyedh anly at 170m/s If the block is stationary on a frictionless surface when hhdwqxeyy m qi rt(/xh3l3yk9+efw 7, :wst0.* it, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket is traveling adfri7h8 :( tuxt 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 with a v*f1qw)3bmcp y elocity of 115m/s To al*1cmqwb3)fp y ter its course by 35.0 $^{\circ} $, its rockets can be fired briefly in a direction perpendicular to its original motion. If the rocket gases are expelled at a speed of 1750m/s how much mass must be expelled?    kg

  A golf ball of mass 0.045 kg is hit off the tee at a speed of 45m/s The go7db k-);e;i qxhawe6r+ os affl+b9 j0lf club was in contact with the ball fo;i-f07+xw qb sja6b;9f d)lahroee+k r $3.5\times10^{-3}$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 c3mqrgkm2o. xl d;9n 90jkbe:a velocity of 8.5m/s and comes to rest in a time interval of 8.0 ms. (a) What is the 99 2m;nelbqk.dm jg:o0r x 3kcimpulse 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 strikesolcci;jc4l: . 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 ebd4-c4f fipap,xppvj:*f o. -ngineer 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 f 4:-i.ppxpj pb4 c*-fo v,dafof 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 and is stopped in 0.75 s yyb +o(*i 2mb2v6w kobby a head-on tackle by a tackler running due west. Calculate b62 k+ wmobyv*biyo( 2
(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) poja2(c1i kxoq3 s b.um qs/3en.ints in the +x direction and is given by the graph of Fig. 7–33 as a function of time. U xqjmb3oq/ns31 e(i2.s.kc ua se graphical methods to estimate
(a) the total impulse given the ball    N*s
(b) the velocity of the ball after being struck, assuming the ball is being served so it is nearly at rest initially.    m/s

  From what maximum height can a 75-kg person jump without breaking the pc0 x hjf2b44ilower 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 breakpxbi0c jfh424 ing 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 kg0tl33s zzyia: 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 oz3tz3ya 0sil:f each ball after the collision?Let A represent the 0.440-kg ball, and B represent the 0.220-kg ball. $v'_A$    m/s  ----待选择----eastwest  $v'_B$    m/s  ----待选择----eastwest 

  A 0.450-kg ice puck, moving east with a speed of 3m/s has a head-on collision wo xrr ,jz*7px-,bkt( s uv:;0nncbi8cith a 0.900-kg puck initially at rest. Assuming a perfectly elastic collision, what will be the speed and direction of each kb,;pnc7tz-r0xi u(o*cjr nxb vs:8,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 o avso ar,3gtjjf6(- f4faq6j: f equal mass undergo a perfectly elastic head-on collision. If one ball’s initial speed was 2m/s and the other’s was 3m/s in the opposite direction, what will be their speeds after the collision?(Let A represrg-: ajqofj 66v ,atas34fj f(ent 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.z 1/gx*xs+ahy 4 9cefped9wmwd- 1w:d5m/s collides head-on with a 0.090-kg b*-9wp41ae g1 mz c:wf/+ exdwd9s xhdyall 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 0.090-kg ball.)v'$_A$ =    m/s v'$_B$ =    m/s

  A softball of mass 0.220 kg that is movg :8zgkhc1 uk.ing with a speed of 8.5m/s collides head-on and elastically with another ball initially at rest. Afterward the incoming softball bounces backward with a spe:.1hkgg 8czuked 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 collide elastically as one apprn q3wq y;q men-eu1)hej8q /o;oaches 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. I hon-;/3 eene 8qqw1jqq my);uf 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 collision with a second ball i)y.vw*)z+iao vj,h idqf55 k jnitially at rest. The second ball moveswzivoyj5 h))ki+.qa df j,5*v off with half the original speed of the first ball.
(a) What is the mass of the second ball?    kg
(b) What fraction of the original kinetic energy $(\Delta\mathrm{kE/KE})$ gets transferred to the second ball?   

  In a physics lab, a cube slidcadlimr(,4 pnn a9 ):ces 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 ,9r)a :c(4nmlndapc ithe 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 object of mass mbqchgqp8 54b5fh ,sfso ,mz :0$_A$ 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 height h xmdd/iq:r5etoxxb4 f* u01m +of e m b5ut4fd0rq:*/+mioxxx 1dthe pendulum equal to 2.6 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 a 3.6-kg pendulum hangiegi)s0;8pkt vf gsx c2e:/)kh ng on a 2.8-m-long string, which makes the pendulum swing u2 e):k gtx/)fhgsp ;cesv80kipward 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 fract,qx nz((eas ha3z 6za*ion 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, initially at rest, into two pie 9st)hu:xb vr45mpy y;ces, one of which has 1.5 times th u : bmprhy945t)vxy;se 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 stopped ag43lzp 2v h;0vxkko9 et a red light. The bumpers lock, the brakes are locked, and the two cars skid forwarzp keh;vo9lx3g24 0k vd 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/jy,r i9)a i 1hw,c 7rrcl2zic height of 1.20 m. Approximately how many rebounds will th 2hc,icac),yl19 wri /rij 7rze ball make before losing 90% of its energy?   

A measure of inelasticikx/z)jz rk( 0e; 4 ionzg*qf;ity in a head-on collision of two objects is the coefficient of rgiz/kze4r x;) 0q*i;z fjk n(oestitution, 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 iny4h :aoisd 0xfi.a2y3s/ e,ddto two pieces, 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 blocihsd ad s:afo,i x 43/d2.ye0yk 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/sst,vkg /9c ew* collides head-on with a 10.0-kg object moving in the wkv ,get9*sc /-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 e-hblx rxm2*) rlectron, and a neutrino. The elect br)l 2xx*-rmhron 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 m1(spj pwd:q 63 h9rfwxass $m_\mathrm{A}=0.400$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 equa1/eft,d:o7ij zl wrt 9l mass, each haviotj, rlzw79/t ed1if:ng 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 mass move at right angles and l94d, q 5xhre .hbs9gcmeet at the origin of an xy coordinate system. Ball A is moving upward along the y axis at 2m/s and ball B is moving to the right along the x axis with speed 3.7m/s After the collision, assumed elastic, ball B is moving along the positive y axis (Fig. 7–37). What is tq.l s 4c95 h,rxehbg9dhe 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 f d4b8k w3ig5uhpt+w (2c/pvz atom at resg8p/tcupb +fzw2(vi 53h dkw 4t. After the impact, the neon atom travels away at a 55.6 $^{\circ} $ angle from its original direction and the unknown atom travels away at a -50 $^{\circ} $ angle. What is the mass (in u) of the unknown atom? [Hint: You can use the law of sines.](Let A represent the incoming neon atom, and B represent the target atom) $m_B$   u

  A neon atom (m=20u) makes a perfectly elastic collision with a)g ml6zmk 8gmm4y)ci 1nother atom at rest. After the img8g4mk)c 6li mm )1myzpact, 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 fy3xk s7,( ,8pwutylwthree-mass system shown in Fig. 7–38. Specify relative to the lefl f8sk3 w(yp, xw,ut7yt-hand 1.00-kg mass.    m

  The distance between a carbon atoxp4j-o+cd2p j 60jufkm ($m_{\mathrm{C}}=12\mathrm{u}$) and an oxygen atom ($m_{\mathrm{O}}=16\mathrm{u}$) in the CO molecule is $1.13\times10^{-10}$m How far from the carbon atom is the center of mass of the molecule?    $\times10^{-11}$m

  The CM of an empty 1050-kg car is 2.50 m behind the front of the car. 2op6 hazyn/bnk q *55h +yyin(How far from ainp 5qz* on(khy5y y h6/bn2+the front of the car will the CM be when two people sit in the front seat 2.80 m from the front of the car, and three people sit in the back seat 3.90 m from the front? Assume that each person has a mass of 70.0 kg.    m

  A square uniform raft, 18 m by 18 m,pz)x/e,hb:x.dqnpz 1 of mass 6800 kg, is used as a ferryboat. If three cars. / xqpe,b:xh1dz zn)p, each of mass 1200 kg, occupy its NE, SE, and SW corners, determine the CM of the loaded ferryboat.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of sides6tiveo, b d(,p -gb8dt $l_0$,$2l_0$, 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 paste0kvg4 6ul* nck* wqt )giow).j (see Fig. 7–40), each of which is a cube of length l. Find the center of gravity in the horizontal plane, so that tcwwti0 vogj4 g*)kk6)u. n*lq he crane operator can pick up the load 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 7 g m2 ox-l2vkvdcx-p wh0f70xof it. The center of the smaller circle is a distance 0.80R from7ocd kp0 lg xv27-xx-0 w2mvhf the center C of the larger circle, Fig. 7–41. What is the position of the center of mass of the plate? [Hint: Try subtraction.]   R

  Assume that your proportions are the same as those in Table 7–1, and calcula 9pv 3w*wxzl 9tm(hv e2;rt-ft2ap9 txte the mass otf(x39 tvplw;*w te 9tpmzx92a2 rv- hf one of your legs.    kg

  Determine the CM of an outstretched arm usimcrul ) za*99yng Table 7–1.   % of the person's height along the line from the shoulder to the hand

  Use Table 7–1 to calculate the position of the CM of an armfg7su*u 46 izd bent at a right angle. Assume that the person is 155 cm tall.i*u 7gfud 4zs6 $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in a position such that his arms and legs are hanging vertf 1 r(x(ec+iwrically, and his trunk and head arx ircw+r( f(e1e 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 an* (* rsh*abvjjd 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 -70(yaya9bimoqad q ) 10.0 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 uniform cy(89jcl1w suq)w * 9ji-sstvcjlindrical 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 tossswcwsq-*18 vlsu )c9tijj(9jed, 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 mass 2.00 kg and a diaa d 9 ky/i:fqj,rrwk;/meter 0.0800 m mounted on a uniform cylindrical handle of mass 0.500 kg and length 0.240 m, as shown raj:ydf;rkq/ w/, ki9in 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 7–14 (Fgc jv2sr--+e cig. 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 itsdl 965 xh3c v5klkr:is gondola, of mass 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 and direction (relative to Earth) does the balloon then move? What happens if the passeng3id5lxk6 9lhkrs c v:5er stops?

  An 0.145-kg baseball 4jcte7h 6omqxj -yp 6+pitched horizontally at strikes a bat and is popped straight up to a height of 55.6 mq+h76j xc4jt6 ey-pmo. 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 speel -hpdkxpelq5lbvj *d2q,9, 1 d $v_0$ 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 corner pocket shot show+w q1(,zvcktynt .(rfkq7/ga n in Fig. 7–43. Relative dimensions are also shown. Should the player be worried about this being a “scratch shot,” in which the cue ball cvw+ q 1a g7ktq./f(yk,zn (trwill also fall into a pocket? Give details.

  A 140-kg astronaut (including space suit) acquires a sp5 atxo.8 w,2okuw neu9eed of 2.5m/s by pushing off with haoxo uw2,e .ut85wn 9kis 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 plp7m:.j;pnzla4k fbhc( 9/ bthe other 80 kg, are initially at rest in outer space. They then pukbc(;bzjh 49l.am/ l 7npfp:psh 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 elastic collision with a second bal6ogu7on,d( ifwjn/g; l (at rest) and;i6nj douw g,f7n/og ( rebounds in the 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 ca d1/6fxg3nom 44y lhwzse involving an automobile accident. The accident involved car A of mass 1900 kg which crashed into stationary car B of mass 1100 kg. The driver of car A applied his brakes 15 m before he crashed into car B. After the collision, car A slid 18 m while car B slid 30 m.o 41/ mgxdnlh63wf 4zy 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 totarub-m f78fh, n9cbg/c9a e;xpl 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 -9 xe7fbhbgac;8 ,9 fprn/ mcuheight 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 .d:-k ev ysfu 5d)/f8pe*cngedirectly above it. If the bullet has a mass of 29.0 g and a speed of 510m/s how highyk f5u pv)8d*s e- ed.eg/fn:c will the block rise after the bullet becomes embedded in it?    m

  A 25-g bullet strikes and becomes embedded in a 1.35-kg block of wood hxz n:k re)(99osyq (rplaced on a horizontal surface just in front of the gun. If the coefficient of kinero9rs) hx :yk(nzq9(e tic friction between the block and the surface is 0.25, and the impact drives the block a distance of 9.5 m before it comes to rest, what was the muzzle speed of the bullet?    m/s

  Two people, one of mass 75 kg and, vqhg3a5 36gmofe+ve the other of mass 60 kg, sit in a rowboat of mass 80 kg. With the boat initially at rest, the two people, who have been sitting at opposite ends of the boat 3.2 m apart from eac 3aheg3vfgmveo65,q+ h other, now exchange seats. How far and in what direction will the boat move? The boat will move    towards the initial position of the 75 kg person(Round to two decimal places)

  A meteor whose mass was about 0lb+oh7ney. hg,uri 1f,s hev8bi8*k$ 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 by8i y oan4oxl:4 an explosion. One fragment acquires twice the kinetic energy of the othey x 48o4aln:ior. What is the ratio of their masses?   

  The force on a bullet is given by thv*lvt)8 yti e)e 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 z(vn5)yilc8i $m_A$ = 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 ra7c i1hfl6nn+q 3q 2xxsjgt+r )dioactively into an alpha particle and a smaller nucleus. What will be the speed of this recoiling nucleusx+)2 cihngnt s3q 76fl1rj+qx 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 target3y-jhms.9kva +9lumf) is fired at an angle of 30 $^{\circ} $ to the horizon with a speed of 25m/s (Fig. 7–45). When it reaches the maximum height, it is hit from below by a 15-g pellet traveling vertically upward at a speed of 200m/s The pellet is embedded in the skeet.
(a) How much higher did the skeet go up?    m
(b) How much extra distance, $\Delta{x}$ does the skeet travel because of the collision? $\approx$   

  A block of mass m=2.2kg sltnoy,6vrdhx:y:c mrt*b u,8,ides 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 thejldun*n /oe083td2o v upper limit on mass m if it is to rebound frdojet03 * dnv8un/ l2oom M, slide up the incline, stop, slide down the incline, and collide with M again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slingshot effect. Fig v/ dvitvxqlni5(t3cc+4-u xia;a 00wure 7–47 shows the planet Saturn moving in the negative x direction at its orbital speed (with respect to the Sun) of 9.6km/s Thi5+t /v-i004 v;ual3w( ax vcindxcqte 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