We claim that momentum is conserved, yet most moving objects eventually qqrs6he,w-9 j slow down and stop. w6,j9heqq- srExplain.

When a person jumps from a tree to1 fv,um/ . f65megl of2arrqx. the ground, what happens to the momentum of the person upon striking th 1x fu 6flmr. 5.m/gea,vqr2ofe ground?

When you release an inflated but untied balloon, why does it fly across thp+huhf b w-e +3djszj 9x-t-9he room?zxf tw-p-3b-9jsjhu 9e dhh++

It is said that in ancient times a rich man with a bag of gold co0 gj g;nf,1tuor(, kyoins froze to death while stranded on a frozen lake. Because the ice was frictionless, he could(1tkog,r n j,yfg0uo; not push himself to shore. What could he have done to save himself had he not been so miserly?

How can a rocket change direction when it is far out in space and is esd v.x6v i5.ov7r.puc toz3pb0sentially in..vupbcxr65ioo z t7v0p.d3 v a vacuum?

According to Eq. 7–5, the longer the imp: sdu 3a,dl56omp6qtnact time of an impulse, the smaller the force can be for the same momentum change, and hence the smaller the deformation sqduotml 566dnp: a3,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 pos ,p:/fzi( bctk wyl+bli) .tx;g/qb6wsible to withstand collisions. Today, though, cars a il )tzx(bt,6l/wfbb.iqc;p/ykg w+: re designed to have “crumple zones” that collapse upon impact. What is the advantage of this new design?

Why can a batter hit a pitched baseball furtherxkw,m7s5 xid;c j4c.x than a ball tossed in the air by thekc 4;7xm si.,wjx5 dxc batter?

Is it possible for an object to receive a larger impulse from a small fo sts)191j ecncu,u shpe0yi4 0rce than from a large force?h4y uji,1 n1e uct9s0s0p)sec Explain.

A light object and a heavy object have thepxyju v;5rzr,;a)le xq/oe5 9 same kinetic energy. Which has the greater momentum? e orl5vp9r5y )xza/;eq;, jxuExplain.

Describe a collision in2(4b -d xqnonm2u gm zc:b;jphnx2/v( which all kinetic energy is lost.

At a hydroelectric power plant, water is di(mxz(nzh65c czir* :l rected at high speed against turbine blades on an axle zl*z r(z(5c h :cixmn6that turns an electric generator. For maximum power generation, should the turbine blades be designed so that the water is brought to a dead stop, or so that the water rebounds?

A squash ball hits a wall 6 z8 ftfr1quv+ewd5m4at 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.3 90scuvz dp8kw8b6o57d iebtc mzm( h onto a hard steel plate (fixed to the Earth), from which it rebounds at very nearly its original speed. (a) Is the momentum of the ball conserved during any pdumc5ismpvek0zc3.(8 6w bz bt87d9o art 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 that falls and sticks to the steel plate.

Why do you tend to lean backward when carrying a heavy l4 4 /1dn41ijguhlcdb*s* bbx poad in your arms?

Why is the CM of a 1-m length of pipe at 7lm6idal,1o y its mid-point, whereas this is not true for your arm oimldl,y 671o ar leg?

Show on a diagram how your CM shifts when you chavrb d 3ny-bk:zk.vbp f6i*+1 7imm+mange from a lying position to a sii7v -z1kiv b3+.dbmpa+fm 6:nky*rm b tting position.

If only an external force can change the6(y c :p6jhvwe momentum of the center of mass of an object, how c(e6h:wjy6p cvan the internal force of an engine accelerate a car?

A rocket following a parabolic path througdusbmn5xxeb58r 8 vn1 a cvi;8:+q vk4h the air suddenly explodes into many pieces. What can you d 8 en1;v cqi+:um8ax8s5v4 xnkbvr5b say about the motion of this system of pieces?

  What is the magnitude of the momentum of a 28-g sparrow flying with ;uplr5u -6h ; rserpwx4m1o6i a speed of $8.4 \; m/s$    $kg \; m/s$

  A constant friction force of 25 e bb6ai36h:jzd ;jt/tN acts on a 65-kg skier for 20 s. What is the skier’s change in veloc6 jjh; /:6taedb b3itzity?    m/s

  A 0.145-kg baseball pitc 6xli xcyhu561hed at 39 m/s is hit on a horizontal line drive straight back toi x5c 6lxyuh61ward 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 6.40x ny+8udzoeu*x8 su3kh3ku 98-kg package out horizontally with a speed of 10 m/s Fig. below Calculate the velocity of the boat immediately after, assuming it wy z k8k889shedux3xuun3+*ou as 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 exery:y )xx sk0ex.ted on a rocket, given that the propelling gases are expelledxkxys0 . y:e)x 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 movi3*udk9oj g9mj 6hb u/ang at $4.1 \; m/s$ on an apparent breakaway for a touchdown is tackled from behind. When he was tackled by an 85-kg cornerback running at $5.5 \; m/s$ in the same direction, what was their mutual speed immediately after the tackle?    $m/s$

  A 12,600-kg railroad car travels alone on2f y(9ts ezwi( alevel frictionless track with a constant speed of 18m/s A 5350-kg load,initially at rest, is dropped onto the car. What will be the car’s newtf(e9siw z(2 y speed?    m/s

  A 9300-kg boxcar traveling atjj;wa-k z ptl/.+ fi4j $15 \; m/s$ 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 horizontally at speeds we/q r7,qodc a)wg2ttu 89ih (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 wid ( ho)t t8d7ra q9gwecuqw2i,/e. 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 gb lj *wx/ofq(w unt*zq.4 n2tul9)6 pof 8.6m/s on a level track. Snow beg *n4 u26 .b(zx)tjqlgwpfqow l9nt/*u ins 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 alpeof9ch5pefj-2 v hr 001fpw :eha 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 wpheo0 fe hpj92cf : 0v1re-f5of 222 u, what speed does the alpha particle have when it is emitted?    m/s

  A 23-g bullet traveling 23)-r 7 -hh3o/* jqezhobfk2ibbpq,w*qvns+ (y0m/s penetrates a 2.0-kg block of wood and emerges cleanly at 170m/s If the block is staw-/o,jb-b7iqqhpo* r+v sfk2(h ynez 3 q*)hbtionary on a frictionless surface when hit, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rocket is traveling at a speed 0m(vct9lik/uof $5.80\times10^3\mathrm{~m/s}$ 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 iny7fd7bv tn5qu,9 w b6y outer space with a velocity of 115m/s To alter 5,wd 7buq yy 7nfv9bt6its 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 te;* jdci7 hlcgg0-3 iafe at a speed of 45m/s The golf club was in contaccjgc0;ailhg-3 fd* 7 it 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 velocit vvp0*+:ak0 hyu.wfq ty of 8.5m/s and comes to rest in a time interval of 8.0 ms. (a) What is the impulp*vqt wku +f:h0.vya0se given to the nail?    kg*m/s
(b) What is the average force acting on the nail?    N

  A tennis ball of mass 0c60pb9cx aesta-s 4k6 6xfhh m=0.06kg and speed v=25m/s strikes a wall at a 45 $^{\circ} $ angle and rebounds with the same speed at 45 $^{\circ} $ (Fig. 7–32). What is the impulse (magnitude and direction) given to the ball?   kg*m/s to the  ----待选择----leftright 

  You are the design engineer in charge of the crashworthiness of new automobhg:uf/9to )fyile 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 force exerteghu)tf f9 :/oyd 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 by .ob5ojn z)m7l h6woz1 a head-on tackle by a tackler running due west.6m wjbzlon5o1o .zh)7 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 ;yb4 h(:9xt im nawy.5ih: .u7d dxdzg(mass 0.060 kg) points in the +x direction and is given by the graph of Fig. 7–33 as a function of time. Use graphical methods to es; iui:yn y.d7a9 hx:5wdt b4.xgdmz (htimate
(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 heigh*:bjao.0fsmz t can a 75-kg person jump without breaking the lower leg bone of either leg? Ignore air resistance and assume the CM of the person moves a distance of 0.60 m from the mjz.0:af bs *ostanding 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 di e/ h7oaozjyzl:*2-oprection) with a speed of collides head-on with a 0.220-kg ball at rest. If:j-ephy 7oa2*zolo/z the collision is perfectly elastic, what will be the speed and direction of each ball after the collision?Let A represent the 0.440-kg ball, and B 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-oncpr,/ ib lzo fy*ev0(/ collision with a 0.900-kg puck initially at rest. Assuming a perfectly elastic collisio fbly0i*c z,ve(/r/pon, 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 masnj y3+)e6 qq.sx wmg;tbsol5 6s undergo a perfectly elastic head-on collision. If one balo3j5e.gts6;6lmqq+ n y) ws xbl’s initial speed was 2m/s and the other’s was 3m/s in the opposite direction, what will be their speeds after the collision?(Let A represent the ball moving at 2.00 m/s, and call that direction the positive direction.Let B represent the ball moving at 3.00 m/s in the opposite direction. ) v'$_A$ =    m/s v'$_B$ =    m/s

  A 0.060-kg tennis ball, moving with a speed of 2.5m/s collides head znatvt8e0;wc tj 4p25-on with a 0.090-kg ball initially moving away from it at a speed of 1.15m/s Assuming a perfectly elastic collision, wha5tzac 82p0enwt vtj;4t 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 av+i ix:*. i w:9wv,vcvbfay+ is moving 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 ofwvf+v *i.xvc b:av,w+ai: 9yi 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 l )l usc6sv9:rcollide elastically as one approaches the other directly from the rear (Fig. 7–34). Car A has a mass of 450 kg and car B 550 kg, owing to differences in passenger mass. If car A approaches at 4.u sl)l:cvs9r65m/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 collzsh yr;n3drhv5*w(m: 5z6-*h u bocvxision with a second ball initially at rest.hhc*v:5-xsowvhm* y n6 b zr5ur;3( zd The second ball 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 slide mkajh,:k2bi0dl3k v8 s down a frictionless incline as shown in Fig. 7–35, and elastically strikes another cube at the bottom that is ika3hj2 lb,80:d kvk monly 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 object m7t4d xql.rsod1h/ u-xmc (2 hof mass m$_A$ and velocity v$_A$ elastically striking a stationary object of mass head-on. (a) Show that the final velocities v'$_A$ and v'$_B$ are given by$v_{\mathrm{A}}^{\prime}=\left(\frac{m_{\mathrm{A}}-m_{\mathrm{B}}}{m_{\mathrm{A}}+m_{\mathrm{B}}}\right)\nu_{\mathrm{A}},v_{\mathrm{B}}^{\prime}=\left(\frac{2m_{\mathrm{A}}}{m_{\mathrm{A}}+m_{\mathrm{B}}}\right)\nu_{\mathrm{A}}.$(b) What happens in the extreme case when m$_A$ is much smaller than m$_B$ Cite a common example of this. (c) What happens in the extreme case when m$_A$ is much larger than m$_B$ Cite a common example of this. (d) What happens in the case when m$_A$=m$_B$ Cite a common example.

  In a ballistic pendulum experiment, projectile 1 resultsuu13ck8cs l2:c u kqg62f; xey in a maximum height h of the pendulum equal to 2.6 cm. A secondyxck 2:s2ce 61ucl fk;3q guu8 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 itse:6 ht kfdw;ltc(1 f6eylf in a 3.6-kg pendulum hanging on a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine th:h6;y1tw(fe6l fdktce vertical and horizontal components of the pendulum’s displacement.vertical$\approx$    m horizontal =    m

(a) Derive a formula for the fraction of kine0;/1 ei u-1 vpj9w9stgrvcrx ctic 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, initiallyiii 1bgk58avilpg 0 x0fy)f16 at rest, into two pieces, one of which hax8ii ff p6 vb1ia501gg0y lk)is 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 collides into the rear end of a 2300-kg SUV stopped aty0n djtxkt(94d.b) dx a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8 m before stopping. The police officer, knowing that the coefficient of kinetic friction between tires and road is 0.80, calculates the speed of the sp()dktj4.9 tddy0b nxxorts 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 - aeq)/ nrfkdvk 9v;0b1.50 m and rebounds to a height of 1.20 m. Approx)/-9v fbq k0dvn;arekimately how many rebounds will the ball make before losing 90% of its energy?   

A measure of inelasticity in a head-3; jdawk- w ;4lwnhd2jon collision of two objects is the coefficient of restin hj3ja dk24;-l;wwdwtution, e, defined as$e=\frac{\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}}{\nu_\mathrm{B}-\nu_\mathrm{A}},$
where $\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}$ is the relative velocity of the two objects after the collision and $\nu_\mathrm{B}-\nu_\mathrm{A}$ is their relative velocity before it.
(a) Show that e=1 for a perfectly elastic collision, and e=0 for a completely inelastic collision.
(b) A simple method for measuring the coefficient of restitution for an object colliding with a very hard surface like steel is to drop the object onto a heavy steel plate, as shown in Fig. 7–36. Determine a formula for e in terms of the original height h and the maximum height h’ reached after one collision.

  A wooden block is cut into two pieces, onsd rdhw2kx 4h 89j-cyau5ix5(e with three times the mass of the other. A depression is made in both faces of the cut, so that a firecracker c(dhs8dyaw52r ij 4kuh5x9 -c xan 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 co *zetkfo.rxcv3/8ts7llides head-on with a 10.0-kg objsr/vot8* f. cxzt73e kect 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 selbmbqc,x .2v*cond nucleus, an electron, and a neutrino. The electron and b qv*x,lb .mc2neutrino 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 masn9x5.xvi /dt2ywhepty6 m k s(xc56/ys $m_\mathrm{A}=0.400$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 inel yd.).)bysus kq7k ou5astic collision between two objects of equal mass, each having initiku.qbysksuyo) 7 5).dal 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 meet at thqqr xhe ))1k:2flsah25r4 q rve 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, assqak:452h)qer frs lq1r2)vhxumed 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 (ww4d eptvm -uk(tg6+ a perfectly elastic collision with another atom at rest. After the impact, the neon atom trave((tewm g-6 dpu+vtw 4kls 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 cog-+ vgsmhq9 (ftr5t)sllision with another atom at rest. After the impact, the )9t gvs+ tg-h(fqm5rsneon atom travels away at a 55.6 $^{\circ} $ angle from its original direction and the unknown atom travels away at a -50 $^{\circ} $ angle. What is the mass (in u) of the unknown atom? [Hint: You can use the law of sines.](Let A represent the incoming neon atom, and B represent the target atom) $m_B$   u

  Find the center of mass of the three-mass system showny9d8 quopgv+4k:oad ) a /,jya in Fig. 7–38. Specify relative to the left-hvu4kja pod9dy):q a8g ya +,o/and 1.00-kg mass.    m

  The distance between a u8+vy )hg e6vqcarbon 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-kgdlp- *ii7u0f7v8f q.1z rc1 i ni)tfta car is 2.50 m behind the front of the car. How far from the front of the car will the CM i8v f *dpu)i1.ilzt 7-rn cqa71 tffi0be 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, of mass 6800 kg,xvna p. q4 jj*ngn9 5((ojkvr;/9qgna is used as a ferryboat. If three cars, each of mass 1200 kg, occupy its NE, SE, and SW corners, dete; 9/ 4x *gj9nnjqopgr(.q(ajkavnvn5 rmine the CM of the loaded ferryboat.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of sidesxwco6beu 7jrop/k/ *r 1*x bi7u)e0us $l_0$,$2l_0$, 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 bmx8pu (0vhf4 paste (see Fig. 7–40), each of which is a cube of length l. Find the centef4 v8u(0bxhmpr of gravity in the horizontal 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 has a circular hole of ra6 f fe:)(jbbxgqg1ohm 9ua(:odius R cut out of it. The center of the smaller circle is a distance 0.80R from the center C of thbf q6(9)ghm1jx (gu ooa:be:fe 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 calculat rou 25gxmqy62e the mass of one of your leg526xq ymr2gu os.    kg

  Determine the CM of an outstre 7* ey0mt3 g h-,ols9f3onsexftched 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 p+sr ;0xt 2bufi+o,0fx:pldx iosition of the CM of an arm bent at a right angle. Assume that the person is 15fux+b2 0; p,dslo itx:+0xr fi5 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in a position such that b5/5+t j9h v gvwjv2amhis arms and legs are hanging vertically, and his trunk and head are horizontal, calculate how far below the torso’s median line thehmvjj w5a9t2g b/vv 5+ CM will be. Will this CM be outside the body? Use Table 7–1.

The masses of the Earth8dkg,q.afa*wft 5 u1k and Moon are $5.98\times10^{24}$kg and $7.35\times10^{22}$kg respectively, and their centers are separated by $3.84\times10^{8}$m (a) Where is the CM of this system located? (b) What can you say about the motion of the Earth–Moon system about the Sun, and of the Earth and Moon separately about the Sun?

  A 55-kg woman and an 80-kg man stand 10.0 m apart on frictionless icu k+ne-uk (uf4 0:+8p3vz8kync n nyple.
(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 ha*q9udmt )v1gj1fv e/ead 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 tossed, spinning, into the air, how far above the bottom of the handle is the point that wiltuf*1va/ 1e9)jgm v qdl follow a parabolic trajectory?    cm

  A mallet consists of a uniform cylindrical head of mass 2.00 kg and a d,tp/3iyx5n3ly)t n c uiameter 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 tossed, spinning, into the air, how far above the bottom of the handle is the po,3t u35nti/ yxyp lc)nint that will follow a parabolic trajectory?    d    d

  (a) Suppose that in Exam1jasuxcu 4q:s ,do0*52rdlh kple 7–14 (Fig. 7–29), $m_{II}$=3$m_{I}$ Where then would $m_{II}$ land?    d(Round to two decimal places)
(b) What if $m_{I}$=3$m_{II}$    d

A helium balloon and its gondola, of mass M, are in the air an+ q ++uy7 6yzwv1u uq0iv7sflqd 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 f0u1wqly7 sui v7yq v +++6uzqwhat speed and direction (relative to Earth) does the balloon then move? What happens if the passenger stops?

  An 0.145-kg baseball pitchedof1xldh8dn w) j(m (vf a4q28r horizontally at strikes a bat and is popped straight up to a height of 55.6 m. I rfa fjd8wld(hxv81 2q )mn4o(f the contact time is 1.4 ms, calculate the average force on the ball during the contact.    $^{\circ} $

  A rocket of mass m travn;3:aklm+ xro eling with 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 p -vq(jxdh71vo 9u;pw *1enf8smr *lkis faced with the corner pocket shot shown in Fig. 7–43. Relative dimen( qkx7hn v8r1vefjdu ;plwm*19s -*posions are also shown. Should the player be worried about this being a “scratch shot,” in which the cue ball will also fall into a pocket? Give details.

  A 140-kg astronaut (including space suit) acquires a speed of 2.5m/s by puef lq6rrewq:6wmt ;31shing off wi1wf6wm;e 6 trr3qq :leth his legs from an 1800-kg space capsule.
(a) What is the change in speed of the space capsule?    m/s
(b) If the push lasts 0.40 s, what is the average force exerted on the astronaut by the space capsule? As the reference frame, use the position of the space capsule before the push.    N

  Two astronauts, one of mass 60 kg and the other 80 kg,rzqy4ppx4h o ;9vyab;*vl. ozi x6s 07 are initially at rest in outer spacehv.io ysp6z44r*xba p x o7qyl;;v09z. They then push each other apart. How far apart are they when the lighter astronaut has moved 12 m?    m

  A ball of mass m makes a head-on elastic collision with a second b*-icbe7mnsao+,bha5+ruqp il. 7d 5g all (at rest) and rebounds in the opposite direction with a speed equal to one-fourth its ai+oh 7*5imuq7s pda lebn-g .br+ ,5coriginal 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 i s/vr,p(9osm, wfhch03c 2 lyenvolving 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. A2ywssc hpv(,mfl 0,3/hr9 oce fter the collision, car A slid 18 m while car B slid 30 m. The coefficient of kinetic friction between the locked wheels and the road was measured to be 0.60. Show that the driver of car A was exceeding the 55-mph (90km/h) speed limit before applying the brakes.    mi/h

A golf ball rolls off the pgm;y: y9. e 6:) lcgy4abkwjjtop of a flight of concrete steps of total vertical height 4.00 m. The ball hits four times on the way down, each tij y)ge9p:k 46y ljbwgam y:.;cme striking the horizontal part of a different step 1.0 m lower. If all collisions are perfectly elastic, what is the bounce height on the fourth bounce when the ball reaches the bottom of the stairs?

  A bullet is fired vertically into a 1.40-kg block of wood atrvdta611 h0(bb0jk v44b j vvh 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 rise0bdv4kvj 1 b1a 60vrjht(b 4hv after the bullet becomes embedded in it?    m

  A 25-g bullet strikes and becomesdi2fd: nud 0b4 embedded in a 1.35-kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.25, and the impact drives the block a distance of 90fni4d d u:b2d.5 m before it comes to rest, what was the muzzle speed of the bullet?    m/s

  Two people, one of mass 75 kg and the other of mass 60 kg, sit in a t43ruo mgu(:crowboat of mass 80 kg. With the boat initially at rest, the two people, who have been sitting at opposite ends of the boat 3.2o :gur 3m(c4tu 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 vl o+hps - koav)i+;)pwas 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 twos0j3z/* s xx1s,h9cql(lfeo q fragments by an explosion. One fragment acquires twice the kinetic energy of theq *9s xh(q,e x1fsljoscl/ z30 other. What is the ratio of their masses?   

  The force on a bullet is given by the0:i7y : fggslq 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 uedw/y 1s rh bm+v-(adv*b7q* $m_A$ = 40g and $m_B$ = 60g are suspended as shown in Fig. 7–44. The lighter ball is pulled away to a 60$^{\circ} $ angle with the vertical and released.
(a) What is the velocity of the lighter ball before impact?$\approx$    m/s
(b) What is the velocity of each ball after the elastic collision?v'$_A$ $\approx$    m/s v'$_B$ $\approx$    m/s(Round to two decimal places)
(c) What will be the maximum height of each ball after the elastic collision?    m

  An atomic nucleus at rest decays radioactively into an alpha particle and a sm0;gx*3ib fv m/wxr*p8 9eng0snrve/ p aller nucleus. What will be the speed of tnr;i*xsg0b8/e p 9g*3vf 0pwmx/v nerhis 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 aceh - gw3rg5 r2v3hc-ibdr 3g;ngle of 30 $^{\circ} $ to the horizon with a speed of 25m/s (Fig. 7–45). When it reaches the maximum height, it is hit from below by a 15-g pellet traveling vertically upward at a speed of 200m/s The pellet is embedded in the skeet.
(a) How much higher did the skeet go up?    m
(b) How much extra distance, $\Delta{x}$ does the skeet travel because of the collision? $\approx$   

  A block of mass m=2.2kg slides down xd,,tmb ;sd/n a 30.0 $^{\circ} $ incline which is 3.60 m high. At the bottom, it strikes a block of mass M=7kg which is at rest on a horizontal surface, Fig. 7–46. (Assume a smooth transition at the bottom of the incline.) If the collision is elastic, and friction can be ignored, determine
(a) the speeds of the two blocks after the collision,v'$_A$ =    m/s v'$_B$ =    m/s
(b) how far back up the incline the smaller mass will go. $\approx$   (Round to the nearest integer) (Let A represent mass m, and B represent mass M.)

  In Problem 79 (Fig. 7–46), what is the upper limit on mass m l v/b k-ytsk0r /f88(s w1ghidif it is to rebound from M, slide up the incline, stop, slide down thew 81f(rk gtki/ 0- bvy8ssl/hd 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 Satq( hhbfhn k8dul9zvp* 2v;q98urn moving in the negative x d(vklhdv*h98p 8z9 2fbq hu;qn irection at its orbital speed (with respect to the Sun) of 9.6km/s The mass of Saturn is $5.69 \times10^{ 26}$kg A spacecraft with mass 825 kg approaches Saturn. When far from Saturn, it moves in the direction at 10.4km/s The gravitational attraction of Saturn (a conservative force) acting on the spacecraft causes it to swing around the planet (orbit shown as dashed line) and head off in the opposite direction. Estimate the final speed of the spacecraft after it is far enough away to be considered free of Saturn’s gravitational pull.    km/s