We claim that momentum is conserved, yet most moving 3kx dk i+1npq8objects eventually slow down and sto d38q+1xnkpikp. Explain.

When a person jumps from a tree to the ground, what happens to the momentu.hg: t8pytcftg+39lhb ed:n 7m of the person upy:t+cgf8 9:ld7g.eh np tht 3bon striking the ground?

When you release an inflatedl tz1h-z+ :kdk but untied balloon, why does it fly across the room:l+ dzh1z -ktk?

It is said that in ancient times a rich man with a bag of gol23 mfq 6y2mfacd coins froze to death while stranded on a frozen lake. Because the cy62qfam2fm 3 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 wh. 3aag1yy/at ben it is far out in space and is essentially y/ abtyaag13. in a vacuum?

According to Eq. 7–5, the longer the impact time of an impulse, the )4 020lqo n,qxqffpkrjp4k qb67*bk r smaller the 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 po)qqqk 60f7rlpn brk0f,oqb4p 2* j4kxssibility of fracture or death.

Cars used to be built as rigid as possible to w wiilg(;gk0 d0ithstand collisions. Today, though, cars are designe dkigi ;0g0(lwd to have “crumple zones” that collapse upon impact. What is the advantage of this new design?

Why can a batter hit a pitched baseball furtcobd9;upq( y( lnbf 46her than a ball tossed in the air by tyou;lb(f9bqn 6d c 4p(he batter?

Is it possible for an object to receive a larger impulse from a small hfv x,x/(nga4 force than from a large force? Explain.4gx( xav/h,f n

A light object and a heavdcpm 8bso*m-izvktehx1h+u7+ p w7j c8* j, k(y object have the same kinetic energy. Which has the grep7 ju8mz-sihh b+7oe d18*jk*(wk+mp cct, vxater momentum? Explain.

Describe a collision in whiplxl4n bp.,j0ch all kinetic energy is lost.

At a hydroelectric powkr8ah* ou8 iy*er plant, water is directed at high speed against turbine blades on an axle that turns an electric generator. For maximum power generation, should the turbine blades be designed so that the water is brought to i *rkyo8*8au ha dead stop, or so that the water rebounds?

A squash ball hits a wall at a 4b0 okoani012ujpjtunh) 6nu53 m 5mc45 $^{\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 hardjoq-d vtk 3)3w*0af-h ; kt/ar(vwvrd steel plate (fixed to the Earth), from which it rebounds at very nearly its original speed. (a) Is the momentum of the ball conserved during any part of this process? (b) If we consider the ball and Earth as our system, during what parts of the process is momentum conserved? (c) Answer part (b) for a piece of putty t) q /v -v-t d3ro0wrja3kkvw*hf atd(;hat falls and sticks to the steel plate.

Why do you tend to lean backward wh-krk cq l9-/tj 0c nk1:6* ghm,pyborhen carrying a heavy load in your arms?

Why is the CM of a 1-m length of pipe at ie 3-6eojb7 x9 yedwjh tl-,0ysts mid-point, whereas this is not true for your 3 wxjo -d-yjees et9b76,lyh0 arm or leg?

Show on a diagram how your CM sbu.1es(s x -ezhifts when you change from a lying position to a sitting pos x-(bezuse1.sition.

If only an external force can change the momentum of the center of masqhio oc q4*s70s of an object, how can the inh co7*s4qi0q oternal force of an engine accelerate a car?

A rocket following a parabolic path through the air suddenly explodes i4jn9vmzkzn )yz f7b69nto many pieces. What can you say about the motion of this system of6mz4k 9)9jnby7zv f zn pieces?

  What is the magnitude of the momentum of a 28-gph 41h 5o;rcjvkk- c qf:7j/.zg. oyzx sparrow flying with a speed of $8.4 \; m/s$    $kg \; m/s$

  A constant friction forceoj2 j-c z(w89hc gfwq) 1f1lawyg m5k/ of 25 N acts on a 65-kg skier for 20 s. What is the skier’s change in velocit f2jqw9fwgo15yh(-k g)w zja/c lc18my?    m/s

  A 0.145-kg baseball pitched at 39 m/s i4 l8 y4vd-geavs hit on a horizontal line drive straight back toward the pitcher at 52m/s If the contact time between bat a gel v-8yvd44and 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 6.40-1ga lhv22p; uzwz-.ase-jop 1kg package out horizontally with a speed of 10 m/s Fig. below Calculate the velocity of the boat immediately after, assu-2ezz.agpv l1- 2;jaw os1 hpuming it was initially at rest. The mass of the child is 26.0 kg, and that of the boat is 45.0 kg. Ignore water resistance. The magnitude of the velocity of the boat is    m/s

  Calculate the force exerted on a rocket, given that the propelling gases are expxmt5kw a64pmji f16s 3ell 53 aim66 1xmstfjk4wped 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 al 1 nq8guqjuy)kx7( y3t $4.1 \; m/s$ 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 alone on alevel frictionless track wsjw6r.,an ;z+ k23yluui fa)2afsp 9with a constant speed of 18m/s A 5350-kg load,initially at rest, is dropped onto the car. What will be the, .j;ni3 s wrf2s)ypazfaa+l uu29k6 w car’s new speed?    m/s

  A 9300-kg boxcar traveling a w8w*pcqv n xe9q6sw jv):s0b/t $15 \; m/s$ strikes a second boxcar at rest. The two stick together and move off with a speed of $6 \; m/s$ What is the mass of the second car?    $m/s$

  During a Chicago storm, winds can whip horizoi9yf+ )w5 . yce(nmvauntally at speeds of 100km/h If the air strikes a person at the rate of 40kg/s per square meter and is brought to rest, estimate the force of the wind on a person. Assume the person is 1.50 m high and 0.50 m wide. Compare to the typical maximum force of friciy9ue. ny )5mw(v+ cfation $\mu\approx1.0$ 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 railrmbo80z)z vo s*oad car coasts along with a constant speed of 8.6m/s on a level track. Sno ) b8ovmzzso*0w 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 after 90.0 min?$\approx$    m/s

  An atomic nucleus initially moving at 420m/s emits an alpha particle in the dne0 jlbk8pd t v51;n ;/c,uedrirection of its velocity, and the remaining nucleus slows to 350m/s If the alpha particlb,nuelv pej5n0dd/; rc8 tk1;e 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 emerge)gjfi,+ o6lc3licil. b lq-;ks cleanly at 170m/s If the block is stationary on a frictionless surface wlkgq; -)liiob6i.,l3l +c c jfhen hit, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket is t 3iujf9-qqx :kraveling 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 withp 14xpgflmu-fxf a-e4.9sk g) a velocity of 115m/s To alter its course by 35.09p-f)4f -e.sxf1pxl4a u kgmg $^{\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 g6ztx eknk h,wnp .-f74olf club was in contahk4 f6enz .tk7 npw-,xct with the ball for $3.5\times10^{-3}$s Find (a) the impulse imparted to the golf ball,    kg*m/s
(b) the average force exerted on the ball by the golf club.    N

  A 12-kg hammer strikes a nail at a velocity of 8.5m/s and comes tol8-16, dwn vf:avsium rest in a time interval of -8is,a 1u:6vvmwfdl n8.0 ms. (a) What is the impulse given to the nail?    kg*m/s
(b) What is the average force acting on the nail?    N

  A tennis ball of mass m=0.06kg and i5m6;wfh:dsstq/5cn3(nly dd 2g y+espeed 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 vh:kw7ft jim9)rkg +.of the crashworthiness of new automobile models. Cars are tested by smashing them into fixed, massive barriers at 50km/h (30 mph). A nmk: w g +tvkjif)h.97rew 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 at 4h+u; go 1l0d :rzbeje5lpd,+km/s to the east and is stopped in 0.75 s by a head-on tackle byedlo10h k bg +r,ze:;+pd5ul j 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 9q(oc ffh.ims2 ij-*m the +x direction and is given f.iosm h9q-f2(i* cmjby 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 jump without breaking th 6-q 0gl7eld ,)8 brwzsgeo(ble lower leg bone of either leg? Ignore air resistance and assume the CM of the person moves a distance of 0.60 m from the standing to the s7eewd 0,(8bbo-grlz ) 6qlslgeated 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 movi w8p 7/y0*gmxepic se4ng 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 87c*wmpi0xpegs4 ey/ 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 eas ak7yylhqn zy3,y2 us 3is -3v93xx+rbt with a speed of 3m/s has a head-on collision with a uyiy, rhyak ln3+v9b3z72sq 33syx- x 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?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 un+ 4r-dej3x:rynvhw/j7 p t-xt dergo a perfectly elastic head-on collision. If one ball’s initial speed w ne 4 hxr/vj3jt7-p+ tdxw-:ryas 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 collides head-on with a:r/a h 7;whdmm 0.090-kg ball initially moving away from it at a speed of 1.15m/s Assuming a perfectly elastic collision, what are the speed and direction of each ball after the collision?(Let A represent the 0.060-kg tennis ball, and let dhh7wra/ mm:; 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 w nv4 v .jpbfze;3ue:2i) wsk.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 speed of 3.sf.bu2 z:wv)jw ;3en ip e.v4k7m/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 appromh1jddph m*1*aches the other directly from the rear (Fig. 7–34). Car A has a massd h*d m*jph11m of 450 kg and car B 550 kg, owing to differences in passenger mass. If car A approaches at 4.5m/s and car B is moving at 3.7m/s calculate
(a) their velocities after the collision v'$_A$ =    m/s v'$_B$ =    m/s
(b) the change in momentum of each.$\Delta p_{\mathrm{A}}$$\approx$    kg*m/s $\Delta p_{\mathrm{B}}$$\approx$    kg*m/s

  A 0.280-kg croquet ball makes an el 47fdq6bblvt 3astic head-on collision with a second ball initially at rest. The second bal6tl4v3 b7dq bfl moves off with half the original speed of the first ball.
(a) What is the mass of the second ball?    kg
(b) What fraction of the original kinetic energy $(\Delta\mathrm{kE/KE})$ gets transferred to the second ball?   

  In a physics lab, a cube slides down a frictionless incline as shown in yqlgr;k:lioxt 83/o-2cl vs* 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 tabllv3:rx islo/8oq2tl* -gy ;kce 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 anu p6pd;k3o4u 9lep);gy)db go 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 ex:e+0 :pq ntn+pm /xajnperiment, projectile 1 results in a maximum height h of the pendulum equal to 2.6 cm. A second projecp+nmqap 0nt:e/+xn:j tile 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 travelinp:q0s 2hf9mv(r naaa74kq z2jfnm71b g 230m/s buries itself in a 3.6-kg pendulum hanging q7zm12(m 2ak4fba hfsa 0n7p rq :jv9non a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine the vertical and horizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formula for the fraction of kinetic energy losr c3t*,g vhw d1q1*d4 ftngjxg-lvu: o93i3ctt, $(\Delta\mathrm{KE/KE})$ for the ballistic pendulum collision of Example 7–10. (b) Evaluate for m=14g and M=380g

  An internal explosion breaks an object, i wl1y sk(ev ; g5cqslf4,t(-zunitially at rest, into two pieces, one of which has 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 represel etu5,gl(scvkyfz 1-w; ( sq4nt the heavier particle, and B represent the lighter particle. ) KE'$_A$ =    J KE$_B$ =    J

  A 920-kg sports car collides into the rear ihm1si- 7xm*yrx)ch3 end of a 2300-kg SUV stopped at a red light. The bumpers lock, the brakes are3s 1y7mi )ixhcmx* -hr locked, and the two cars skid forward 2.8 m before stopping. The police officer, knowing that the coefficient of kinetic friction between tires and road is 0.80, calculates the speed of the sports car at impact. What was that speed?(Let A represent the sports car, and B represent the SUV) $\approx$    m/s

  A ball is dropped from a height of 1.50 m and r.cz9.mna ,n *6o si,9euaqrpm 1djx3 fxi33vvebounds to a height of 1.20 m. Approximately how many rf63 dumj zniaq3 rvpx e,,o9v sic. .3a*9mnx1ebounds will the ball make before losing 90% of its energy?   

A measure of inelasticity in a head-on c(kf mi)t c19esai5onv 4 herlc8( s(0kollision of two objects is the coefficient of restitution, 4rteh19(ofiissk08 ec5 (c(ma)nvk l 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 pi /xi/m.gb ejt8eces, 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 sepx e/ib.t8/mj garate 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 ;i3 ttq shv8 0tfp91nhcollides head-on with a 10.0-kg object moving inis1 p;nv9tqt80hfth 3 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, ancs - g9i0pkg2ayl *-an electron, and a neutrino. The electron a*g s9g n2lcia0yp--a knd 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 mu*y crwa6240 9op:r7(/gba+pfo9gp difts lnass $m_\mathrm{A}=0.400$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 equalbl h)n6-w19 sw*l8i th4zgqmz mass, each having initial speedqbnmh8)w zt9g*-i14ws ll6 hz 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 7o:0ey+ baycb right angles and meet at the origin of an xy coordinate system. Ball A is moving upward along the +:7ae bcyb yo0y axis at 2m/s and ball B is moving to the right along the x axis with speed 3.7m/s After the collision, assumed elastic, ball B is moving along the positive y axis (Fig. 7–37). What is the final direction of ball A and what are their two speeds? direction of ball A is  ----待选择----x directionx direction v'$_A$ =    m/s v'$_B$ =    m/s

  A neon atom (m=20u) makes a7t9dnxyt9 sh2 perfectly elastic collision with another atom at rest. After the impact, the neon atom travels a7h9tx yd29t snway 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 perfectl-+k+h1 3 g3xknslkna qy elastic collision with another atom at rest. After the impact, the neon atom travels away at a 3aq13+- +kh kkn xnsgl55.6 $^{\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. Se x-*qfe0+u papecify relative to the left-hand 1.00-kg mass. f-ua+p0ex* eq   m

  The distance betweenfi,8bsob0 2-blje va0 a 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 thy5dklw5xz0q3, vboy lfi; ,wbb*8h2ge front of the car. How far from the front of the car will the CM be when two people sit in the front seat 2.80 m from the front of the car, and three people sid2,5b0if5y *wkov,bq;8gz 3y bhxw llt 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 1m;o 4 qg wmw3cxiu1b*38 m, of mass 6800 kg, is used as a ferryboat. If three cars, each of mass 1200 kg, occupy its NE, SE, and SW corners, determine the CM of the loaded ferryboau;x* cw3io3bmq 1w4gmt.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of sidemii , ;/vx)cy:p hkfg1s $l_0$,$2l_0$, 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 lir9 o:9 wgbf(doad of identical cases of tomato paste (see Fig. 7–40), each of which is a cube of length l. Find the center of gravity in the horb riodw( 9:9gfizontal plane, so that the crane operator can pick up the load without tipping it.$X_{CM}$ =    l $Y_{CM}$ =    l

  A uniform circular plate of radius 2R hd5z;oj,d 74 3jgor3ej9t uhhlas 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 tj 3td e5oh9z3ru7,;4hjlo gjdhe 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 cu8(pkghz 3 ;(h:mvlfr alculate the mass of one of your3l mpvf :hzk g(u8(;hr legs.    kg

  Determine the CM of an outstretchdx-j v8ncbs1fd c3w+gr 30 x-ged arm 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 the CM of avvw l*s 5mb2 /,-b mc zpcagpk;s959kgn arm bent at a right angle. Assume tha9p*s m9vk2pccg,w;5gbv 5ka-bmsz/l t the person is 155 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in a position such th:nlf* c/ o8uqmw/d8ozgls19hat his arms and legs are hanging vertically, and his trunk and head are horizontal, calculate how far below the torso’s median line the CM willun* gq8ow1 lhl9 sfo/m:zc8/d be. Will this CM be outside the body? Use Table 7–1.

The masses of the Eak o8 2lkcvg)1avjhc)m0c0 0i wrth and Moon are $5.98\times10^{24}$kg and $7.35\times10^{22}$kg respectively, and their centers are separated by $3.84\times10^{8}$m (a) Where is the CM of this system located? (b) What can you say about the motion of the Earth–Moon system about the Sun, and of the Earth and Moon separately about the Sun?

  A 55-kg woman and an 80xf i,dpwhdi*--p3(w h-kg man stand 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 cylindrical head of mass 2.00eogc3g6j* m( 0.aso 8t ndk;xj kg and a diameter 0.0800 m mounted on a uniform cylindrical handle of mass 0.5gmejtn.gd xk (a83oc s jo6;0*00 kg and length 0.240 m, as shown in Fig. 7–42. If this mallet is tossed, spinning, into the air, how far above the bottom of the handle is the point that will follow a parabolic trajectory?    cm

  A mallet consists of a uniform cylindrical head ofc5 y0*lrs;-kq wjt)jd 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 F5k s);ly jc-dt r0j*wqig. 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 (Fig. 7–29 qx4izk 9r 1)zv/dtd:9wwg2tv6ew 7 ph), $m_{II}$=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 w1u dd,nj fb 8j)vae ehj0m.1s)ith 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 passenger stops?)ej j aje) bfn,0dd1.u s1h8mv

  An 0.145-kg baseball p9)me0*ul b:wpo y5lojitched 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 tmp0 ubyol*l5e:w) oj 9he average force on the ball during the contact.    $^{\circ} $

  A rocket of mass m traveling withpa6j5ch: l g/e speed $v_0$ 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 shown in Fig. 7–43.g pyjwfz0bd 3k/g82 j7 Relative dimensions are also shown/zjgdgbf82k 0 j7ywp3. 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 by pushin7jegn o.mku: +g of. mon+:ue7kjgf with 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 a/y(3x nubq k.w(l ii(vnd the other 80 kg, are initially at rest in outer space. They then push each other apart. How far apart arui.( vwqnlb(3/y xi (ke they when the lighter astronaut has moved 12 m?    m

  A ball of mass m makes a head-on elastic collision with a second ball (at f8arse 9w xadvf9-i,)rest) and rebounds in thesx) fafe8-9 9wvair,d 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 involvin/yti 8js+qjkv6bv.c.o4 -uod g an automobile accident. The accident involved car A of mass 1900 kg which crashed into stationary car B of mass 1100 kg. The driver of car A applied his brakes 15 m before he crashed into car B. After the collision, car A slid 18 m while car B slid 30 m. The coefficient of kinetic friction betwvjd. /iu vy -4o6b.8qsjoct+keen 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 tora7hz m i8ecok69ni;) tal 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 reaches the bottom of thah9 7z;ircoe i6mkn8)e stairs?

  A bullet is fired vertically into a 1.40-kg block of0 ,a2n3if fkkql9uiu( wood at rest directly above it. If the bullet has a mass of 29.0 g and a speed of 510m/s how high will the block i ( l0quiun2kffa,k39 rise after the bullet becomes embedded in it?    m

  A 25-g bullet strikes and becomes embedded in a 1.35-kg p;ftf2 flg82t 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 2l8tt p; f2gffto rest, what was the muzzle speed of the bullet?    m/s

  Two people, one of mass 75 kg and the other of mass 60 kg, sit in a rowboat ofis78p .pmr9oq mass 80 kg. With the boat initially at rest, the two people, who have been sittirs9pq8io . 7mpng at opposite ends of the boat 3.2 m apart from each other, now exchange seats. How far and in what direction will the boat move? The boat will move    towards the initial position of the 75 kg person(Round to two decimal places)

  A meteor whose mass ,zfkebe8gc2,14 k ,n ow+hhdy was about $ 1\times10^{ 8}$kg struck the Earth ($m_E$=$6 \times10^{ 24}$kg) with a speed of about 15km/s and came to rest in the Earth.
(a) What was the Earth’s recoil speed?    $ \times10^{-13 }$m/s
(b) What fraction of the meteor’s kinetic energy was transformed to kinetic energy of the Earth?    $ \times10^{ -17}$
(c) By how much did the Earth’s kinetic energy change as a result of this collision?    J

  An object at rest is suddenly broken apart into two fragments bv 3qxr+rdre m4s-x,k3y an explosion. One fragment acquires twice the kinetic en3d x,qsrevm-+r x4r3k ergy of the other. What is the ratio of their masses?   

  The force on a bullet is given by the*scyinto92 wxhqe / dbh8/*8 r 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 bt7hzh8, /bx qns*/s u( 52cqgqm bh.t$m_A$ = 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 radioact5zt(l og/49t7 o 5hif;uokdn rively into an alpha particle and a smalr ;t7otg uoid5kzh 9(nfl/45oler nucleus. What will 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 an angle of v4 + uwo0;fcr.k 9jfs7amlbn8e zh4)k30 $^{\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 slidestvsmh1 e9u f: b(b.;es down a 30.0 $^{\circ} $ incline which is 3.60 m high. At the bottom, it strikes a block of mass M=7kg which is at rest on a horizontal surface, Fig. 7–46. (Assume a smooth transition at the bottom of the incline.) If the collision is elastic, and friction can be ignored, determine
(a) the speeds of the two blocks after the collision,v'$_A$ =    m/s v'$_B$ =    m/s
(b) how far back up the incline the smaller mass will go. $\approx$   (Round to the nearest integer) (Let A represent mass m, and B represent mass M.)

  In Problem 79 (Fig. 7–46), what is the upperi bf1m;31)ls vk fdd1e limit on mass m if it is to rebound from M, slide up the incline, stop, slbdfmv e )1l;s11dfki 3ide down the incline, and collide with M again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slingshot effect. Figure 7–47 shows the planet Saturn mnl2zxqc9nyxz8)/0v/1 t eoa) o 8vvoyoving in the negative x direction at its orbital speed (with respect to the Sun) of 9.6km/s The mass ofyvxv loq8o 9 /8z a evox/c0nt1)2)nyz 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