We claim that momentum is consexq3f1c)ds tbok5-m ;l(k1o r lrved, yet most moving objects eventually slow down and stop. Explf ro;m5lcs31b lk-1dkq()oxt ain.

When a person jumps from a tree to the ground, what happens to the momentum of t3 fw05 zluwi0mtwk v9(he perso k9vwt 5(3z0u0mwlwf in upon striking the ground?

When you release an inflatenz80do*lkmv-q 9z,u (yeg oot ;t i4-yd but untied balloon, why does it fly across the room,9yo ek (mvlotzg4*iqzt y;u0 -n8o-d?

It is said that in ancient times a rich man with a bag of gold coins froze qku,czbix+zb5ko.j+s 7 27 gwto death while stranded on a frozen lake. Because the ice was frictionless, he could not push himself to shore. What could he have do j+x,bkc7isu+g72zk5 wozbq. ne to save himself had he not been so miserly?

How can a rocket change direction when it is far h+mq m:3qwi j h ),d06j.0tpggqnphh0out in space and is essentially in hh q. g6 pp),dh + tgqnw:j0300mmhjqia vacuum?

According to Eq. 7–5, the longer the impact time of an impulse, the sma kms ,dvf89xri7ik/ ,;)o tjhh0ijj/c ller the jh/9;i ifmod, )/ikh,v8jcjs0t7kx rforce 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 death.

Cars used to be built as rigid as possible to withstand collisi eay-tj af,k1mm;+kb )bu(t2d ons. Today, though, cabd1t )am-;( ufab2,mjkey+t krs are designed to have “crumple zones” that collapse upon impact. What is the advantage of this new design?

Why can a batter hit a pitched bas/z-c2 e9ujt 1wb.w*uweny rq +eball further than a ball tossed in the air by the batte+*u/utw1eywz9cewbq2 j n. -r r?

Is it possible for an object to receive a larger impulse from a sma3ir+ t+ z2jgat1y(ekp7nbli3ugq * l3 ll force than from a large 3l b+3ipj *7gy +3gktt2que airlz (n1force? Explain.

A light object and a heavy object have the same kinetizy7 5, pk: wg*koltr*kc energy. Which has the greater pk,k57 o rwkytg*:*lz momentum? Explain.

Describe a collision in which all kinetic energye s bq6m+ss0kgrmo,(;s4a e0 t is lost.

At a hydroelectric power plant, water is directed at high speed against t-(**obe c+ *tssetahkurbine blades on an axle that turns an electric generator. For maximum power generation, should the turbine blad t*-he(sse+batk* *o ces be designed so that the water is brought to a dead stop, or so that the water rebounds?

A squash ball hits a w;ankbc9pb+8+ :q fj itall 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 pls4v /l2tdz,g;xz nff4 ate (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 that falgzs lv,4 zft4 2fxn;/dls and sticks to the steel plate.

Why do you tend to lean backz r3 zkdmq/,5ue-llj+ward when carrying a heavy load in your arms?

Why is the CM of a 1-m length of pipe atv4bbbg -o4.psuo .e. x its mid-point, whereas this is not true fog4b pboe s. ubv.4xo.-r your arm or leg?

Show on a diagram how your CM shifts when you change from a ly4)7zji7ltty amd. hu .ing position to a sitting . tumthd477y lizja ).position.

If only an external force can change the mmf*u.v ifpu (/omentum of the center of mass of an object, how can the internal force of an engine accelerat*u/ vfm( ifu.pe a car?

A rocket following a parabolic path through the air sudden ee3cnj e+:ls7ly explodes into many pieces. What can you say about the motion of this system of p:sc+ln73 eee jieces?

  What is the magnitude of the momentum ofw-py(q l)tbshx ig5p .dmf./6 a 28-g sparrow flying with a speed of $8.4 \; m/s$    $kg \; m/s$

  A constant friction force of 25 N acts on a 6fkvdryb/ :m(( ,.pbar5-kg skier for 20 s. What is the skie,r pad(f/b:b. kmvy r(r’s change in velocity?    m/s

  A 0.145-kg baseball pitc* /k1 /) nfi1 euhbuudvojz3al5t+ rf6hed at 39 m/s is hit on a horizontal line drive straight back tow d1o6la ff*j3nue h//+v r)uiub1t5kz ard 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 6.40-kg packagezch3)bl /go5t out horizontally with a speed of 10 m/s Fig. below Calculate the velocity of the boat immediately after, assuming it was initially a/cot5 bz )h3glt 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 t zg z79: njby4rg,u:b pql7ecdu;s(y/he propelling gases are expelled at a rate o:sgr (4 u; l,b9:/yzzubeyn7dgcq7j pf $1500 \; kg/s$ with a speed of $ 4\times10^{4 } \; m/s$ (at the moment of takeoff). F =    $\times 10^7 \; N$

  A 95-kg halfback moviad8a1zns:p /*ikw-t;a m -ktbo8c-i ung 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 -ngz5h5bsp c1 alone on alevel frictionless track with a constant speed of 18m/s A 5350-kg load,initially at rest, is dzbgs c-1h n5p5ropped onto the car. What will be the car’s new speed?    m/s

  A 9300-kg boxcar traveling2s )-bvm0eqy l uoy32o 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 sto .i5by rd.2bee:krq8 erm, winds can whip horizontally 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 fo re85b rqyb ek:.2ie.drce 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 spem+r,i mcr+ u,oed 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,ou +r+i,rc,mm what is the speed of the car after 90.0 min?$\approx$    m/s

  An atomic nucleus initially moving at 420m6k).j obep , .yalo5bf/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, what speed does the alpha parti b)l o..pakeoj ,y6bf5cle have when it is emitted?    m/s

  A 23-g bullet travel+h40+t: a )q or;spswrp eift.ing 230m/s penetrates a 2.0-kg block of wood and emerges cleanly at 170m/s If the block is stationare4ft s spr)0aq+w+oh r:ti .;py on a frictionless surface when hit, how fast does it move after the bullet emerges?    m/s

  A 975-kg two-stage rr.a s*10vnff1 +-tiig ofjd5iocket is traveling at a speed of $5.80\times10^3\mathrm{~m/s}$ with respect to Earth when a pre-designed explosion separates the rocket into two sections of equal mass that then move at a speed of $2.20\times10^3\mathrm{~m/s}$ relative to each other along the original line of motion. Let “A” represent the upper stage (that moves away faster) and “B” represent the lower stage.
(a) What are the speed and direction of each section (relative to Earth) after the explosion? $v'_A$   m/s  ----待选择----away from the Earthtowards the Earth  $v'_B$   m/s  ----待选择----away from the Earthtowards the Earth 
(b) How much energy was supplied by the explosion? [Hint: What is the change in KE as a result of the explosion? $a\times10^8$ a =    J

  A rocket of total mass 3180 kg is traveling in outer space with a vel3yz/gn p8ni (cocity of 115m/s To alter its co(pyc38n ngi/ zurse 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.e09p h db/r+7(j.pzgznlz/ tm045 kg is hit off the tee at a speed of 45m/s The golf club was in contact with the0mdpzg rt9.+ (hpej7 n/z/ lbz 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 to reso4s.y niw7us* t in a time interval of y.s *o su47niw8.0 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 speed v=bi / 6a -do(u a(6abje:k;pwcf25m/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 ine4eq,ew 8u9ait z2qnh cw)5 5z 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 ,h5wz9 2qt e5wa)4eucn8qzieof 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 by a a+c ysg0d29qi4a /uyo head-on tg4/2o+ ayyqdac9i us0ackle by a tackler running due west. Calculate
(a) the original momentum of the fullback    kg*m/s
(b) the impulse exerted on the fullback    kg*m/s
(c) the impulse exerted on the tackler,    kg*m/s
(d) the average force exerted on the tackler.    N

  Suppose the force acting on a tennis ball (mass 0.060 kg) pointsq8gwc82a*u e c in the +x direction and is given by the graph of Fig. 7–33 as a function of timacq wc8e*u28g e. 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 the lower vx;7c ms hd.w 1eda,f1leg bone of either leg? Ignore air resistance and assume the CM of the pe1vw7x ded. ha1, sm;fcrson moves a distance of 0.60 m from the standing to the seated position (that is, in breaking the fall). Assume the breaking strength (force per unit area) of bone is $170\times10^6\mathrm{~N/m^2}$ and its smallest cross-sectional area is $2.5\times10^{-4}m^2$ [Hint: Do not try this experimentally.]    m

  A ball of mass 0.440 kg moving east (6ed,-amask2 e +x direction) with a speed of collides head-on with a 0.220-kg ball at rest. If the collision is perfectly elastic, whatmaakes-6, de2 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-on coll q,t9ro5q54n byx v8leision withlet58xq5v yn 4,qb9 ro a 0.900-kg puck initially at rest. Assuming a perfectly elastic collision, what will be the speed and direction of each object after the collision?Let A represent the 0.450-kg puck, and let B represent the 0.900-kg puck. v'$_A$ =    m/s ----待选择----eastwest  v'$_B$ =    m/s ----待选择----eastwest 

  Two billiard balls of equal mass undergo a perfectly elastih:6)s cr43(hplgklj 6 qc;w oec head-on collision. If one ball’s initial speed was 2m/s and the other’s was 3m/s in the opposite direction, what will be their speeds after the collision?(Let A represent the ball moving at 2.00 m/s, and call that direction the positive direction.Let B represent 6(:ol w p;6 rshcec3) hjlkq4gthe 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, movi-ccrkc,z k opo ,srvnt0juk,4s):,g .ng with a speed of 2.5m/s collides head-on with a 0.090-kg ball initially moving away from it at a speed of 1.15m/s Assuming a perfectly elastic collision, what are the speed and direction of each ball after the co.,,,-rjvo gt) zcu k0rc ocskns:p,k4llision?(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 0.2c0 sj: ot pjtx0(*ht6u20 kg that is moving with a speed of 8.5m/s collides head-on and elastically with another ball initially at rest. Afterh jsottjx0t0 pc:6(*uward the incoming softball bounces backward with a speed 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 qb(ou68a9kjm/:ji pxc2ll9q 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 differencekq9x9q blucjm/62al:o8 ip(js in passenger mass. If car A approaches at 4.5m/s and car B is moving at 3.7m/s calculate
(a) their velocities after the collision v'$_A$ =    m/s v'$_B$ =    m/s
(b) the change in momentum of each.$\Delta p_{\mathrm{A}}$$\approx$    kg*m/s $\Delta p_{\mathrm{B}}$$\approx$    kg*m/s

  A 0.280-kg croquet ball makes an elastic head-on collision w c2h2obv ybm6.3.c2ip q q,puzith a second ball initially at rest. The second ball moves ocz h q3obu.,6 2 y2vb2.mpciqpff 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 showt 3f9:q)dqdvk.c bts-n in Fig. 7–35, and elastically strikes another cube at the bottom that is only one-half its mass. If the incline is 30 cm high and the table is 90-d )f:tsvtdqqcb9k 3. 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+y fn(*fk * ldbvt3kj; 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,v zrnop tbv87 1aa6v+7 projectile 1 results in a maximum height h of the pendulum equal to 2.6 cm. A second projectile causes the the pendulum to swing twice as 8p1ra 7v a6b7nz o+vtvhigh, $h_2=5.2\mathrm{cm}$ 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/q7flg,hie )qqu6m:: fs buries itself in a 3.6-kg pendulum hanging on a 2.8-m-long string, which makes the pendulum swing upward in an arc. Determine the vertical and horizontal components of the pendulum’s displacemeqf):q 67 ighe ,lum:qfnt.vertical$\approx$    m horizontal =    m

(a) Derive a formula forwb b8hiue93p 8 p7osm1puv/* d the fraction of kinetic energy lost, $(\Delta\mathrm{KE/KE})$ for the ballistic pendulum collision of Example 7–10. (b) Evaluate for m=14g and M=380g

  An internal explosion breaks an object, initially at rest, into two ouj.wp-:23ldcpy h ;s f,4uxcpieces, one of which has 1.5 times the mass l:x;,-u sw3p2 cucdh.jpo yf 4of 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 bl l1;)oz)vn20u -ztynv 5 cafinto the rear end of a 2300-kg SUV stopped at a red light. The bumpers lock, the brakes are locke25-fz0)ztlyb) cna lvn ;o1uvd, and the two cars skid forward 2.8 m before stopping. The police officer, knowing that the coefficient of kinetic friction between tires and road is 0.80, calculates the speed of the sports car at impact. What was that speed?(Let A represent the sports car, and B represent the SUV) $\approx$    m/s

  A ball is dropped from a height of 1.50 m and rebounds to a height of z:d.*pzy*iru 1.20 m. Appryu :r*pzid*z. oximately how many rebounds will the ball make before losing 90% of its energy?   

A measure of inelasticity in a head-on collision of two objects is the coefficievogn qpy311j, nt of restitution, e, defined 13vqnpjo ,1y gas$e=\frac{\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}}{\nu_\mathrm{B}-\nu_\mathrm{A}},$
where $\nu_\mathrm{A}^{\prime}-\nu_\mathrm{B}^{\prime}$ is the relative velocity of the two objects after the collision and $\nu_\mathrm{B}-\nu_\mathrm{A}$ is their relative velocity before it.
(a) Show that e=1 for a perfectly elastic collision, and e=0 for a completely inelastic collision.
(b) A simple method for measuring the coefficient of restitution for an object colliding with a very hard surface like steel is to drop the object onto a heavy steel plate, as shown in Fig. 7–36. Determine a formula for e in terms of the original height h and the maximum height h’ reached after one collision.

  A wooden block is cut into two pieces, one with three times the mass of the ot 03v zszk1:rmgher. A rz :v13gk0mzsdepression is made in both faces of the cut, so that a firecracker can be placed in it with the block reassembled. The reassembled block is set on a rough-surfaced table, and the fuse is lit. When the firecracker explodes, the two blocks separate and slide apart. What is the ratio of distances each block travels? ----待选择----1/91/101/81/6 

  A 15.0-kg object moving in the +x direction at 5.5m/s collides head-on ue/xkq ebg) uzq n;-.:with a 10.0-kg object moving in the -x direction at ;.kqz g/eq-bunux e:)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 electron, 18 6few87 l xfk4hqlzo;5rm prand a neutrino. The electron and neutrino are emitted at righl 8lezok w7rp14mrx5q 8fhf6 ;t 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 mass oi )nb fiq;6;xnmk(m4 n 6/o0lwenkf, $m_\mathrm{A}=0.400$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 objec/r-u* yh+hdl8ohz tm5ts of equal mass, each having initial speed the two move off together with speed v/3 What was the angle5duh+rl /y- thz mh8o* between their initial directions?    $^{\circ} $

  Two billiard balls of equal mass move at right angles and meet at the origin of -+b bu)+ ip q -x ia8qjvs 90*,dwq3ufrqar0udan 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 aqpi9 qibqf-v axrd3s,+u0 *qau-) 8udjw0b+r xis (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 0u z7e6/cxqrza perfectly elastic collision with another atom at rest. After the impact, the neon atom travels away at a 6erz0/zq7uc x 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 g:v4sf ci-8n*idylx1collision with another atom at rest. After the impact, the neon atom travels l8cv*1ifxdsy ig-n 4: 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 sys8bti: nef80ia tem shown in Fig. 7–38. Specify relative to the left-hand 1.00-kg mas8:0anif bet i8s.    m

  The distance between a carbon atom+b mo7aefh2: h ($m_{\mathrm{C}}=12\mathrm{u}$) 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.u7+mj t/wk.d .kchq+6r bwp)wv al0-j 50 m behind the front of the car. How far from the front of the car will the CM be when two people sit in 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 /wuvq6wjkw+-h7ap) m.br+c0j k t.dl has a mass of 70.0 kg.    m

  A square uniform raft, 18 m by 18 m, of mass 6800 kg, is used as a ferryb4d h(c6zo h02qk qx87bf bdr mf9/jsd-oat. If three cars, each of mass 1200 kg, (xmbjfhz68k f4d7 q/brcos dqh 902 -doccupy its NE, SE, and SW corners, determine the CM of the loaded ferryboat.$X_{CM}$ =    m $Y_{CM}$ =    m

  Three cubes, of sidei j5g j5kl.a8-uqg4xk s $l_0$,$2l_0$, 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 ak) r-j)t3cb u8rb lp6t load of identical cases of tomato paste (see Fig. 7–40), each of which is a cube of length l. Find the center of gravity68t)-pr)ul3b kbjc tr 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 1w09nux:y3h3hu;a3tb0jgzw zy t*lq radius R cut out of it. The center of the smaller circle isa 0wh :wtbn;3jt *3zhy 9 zq03lyxugu1 a distance 0.80R from the center C of the larger circle, Fig. 7–41. What is the position of the center of mass of the plate? [Hint: Try subtraction.]   R

  Assume that your proportions are the same as those in Table 7–1, and calculat(3b0 x7yek uaye the mass of one of your legs. b0ke(y y3ux a7   kg

  Determine the CM of an oujot ,4hmah (t;tstretched 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 fk3tijpy5l6 tpf 9u(1j)qcb 6 of the CM of an arm bent at a right angle. Assume that the person is 19c3ftjfyp 5tu6p6 l) 1 i(bkqj55 cm tall. $X_{CM}$ =    cm $Y_{CM}$ =    cm

When a high jumper is in a position such that his arms and legs j7*of9ey) *hb gw5w)i2ltfto are hanging vertically, and his trunk and head are horizontal, calculate how far below the torso’s median line the CM will be. Will this CM be outsi7*ywj5 2bl gwh)9 )foi teot*fde the body? Use Table 7–1.

The masses of the Earth and Mo3/a2mbnupm:n q5) uhhon 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 frictionlvns06fo2zob)x36o m)zc kjv . rr.we ,ess 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 cylindric w6t)lefke6fd)*kth6by8k8 l al 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 tossed, spinning, into the air, how far a88lyew kt6 lhfd)) fk*et66k bbove 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 diams:m /dhc6xjrhrr5s6; rjf( oq(c*)fbeter 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, ho; (c(f *qd) o6f/h c mxrr:hbj5rr6sjsw 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. 7–2kiegd w 7,2f3h9), $m_{II}$=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 st3tmuxi0 9h fn3nm;u ljx09zr2 ationary with respect to the ground. A passenger, of mass m, then climbs out and 09t f;xn09u33rh imm zn2jluxslides 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?

  An 0.145-kg baseball pitched horizontally at strikes a bat ae+-.kk5tjiipk 30 5kgfd6po fnd is popped straight up5 jkikp i 0.o-gk+dft5pe3kf 6 to a height of 55.6 m. If the contact time is 1.4 ms, calculate the average force on the ball during the contact.    $^{\circ} $

  A rocket of mass m tra 9rky (gnft0p+veling 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 is b*j1 m7tsikgv)hqy4+faced with the corner pocket shot shown in Fig. 7–43. Relative dimensions are also shown. Should the player be worried about this being a “sm+ hbv*qjsg 47i)ykt1cratch shot,” in which the cue ball will also fall into a pocket? Give details.

  A 140-kg astronaut (including sp8rqqam yljl;n62-(wo ace suit) acquires a speed of 2.5m/s by pushing off with his legs from an o8 a(-n qlrw;yl jmq261800-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 yf;4f -c hc7yz80 kg, are initially at rest in outer space. They then push each other aparcy 4h;f-7yc zft. 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 seco4u n, ij -dje2t) 7 -)hfvzd2clt(fpxvnd ball (at rest) and rebounds in the opposite direction with a 7fie ,vtfd2vpdx( -zu- jjnh4l2t))c 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 caseip-9 icz w7jeb8 38zcu 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. 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 i pc ic8w 98zj7-3bzeuwas 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 totalcm/64qcox-ne se.7inbtr s;6 vertical height 4.00 m. The ball hits four times on the way down, each time striking the horizontal part of a different stei7e.xc4 rq b;6- e/o s6ntcsnmp 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 block9cgff zfc5;y4iz fs(3. qxb/z of 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 risfqc4yfg .fzcb ( zz/3i5sf x9;e after the bullet becomes embedded in it?    m

  A 25-g bullet strikes and becomes embedded in a 1.35-kg block of wood placed 0wtt6 27oteqb on a horizontal surface just in front of the gun. If the coefficient of kinetic frictwo 2e0t q6b7ttion 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 the other of mass 60 kg, sit in sdl n1*w. c9 s2ugt2ga-; 9pojv-ftmaa 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.p2ts; cm9*jnlfwa 1g9gd.vs -ta2 u-o2 m apart from each other, now exchange seats. How far and in what direction will the boat move? The boat will move    towards the initial position of the 75 kg person(Round to two decimal places)

  A meteor whose mass was auq4;x ife9r: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 sud*t k s-(zpxua*denly broken apart into two fragments by an explosion. One fragment acquires twice the kin(x su-kzp*at*etic energy of the other. What is the ratio of their masses?   

  The force on a bullet is given by the formutz8)asf6m ,3e d ebazo0,w/npla 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 massesn9rvi)i+wqo- $m_A$ = 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 pg t 60-s0j2*;ebodshfqjw.a8 ku 8vnh article and a smaller nucleus. What will be the speed of this recoilinga82gtj* jwfsq od0 -e60vnk;ubh s8h. 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 5m-qyw plr);g1q b6sl 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 slides dow+dui,w1 8use+ubc cw. jn jq:6n 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 u7e wo 9dcro4;on mass m if it is to rebound from M, slide up the incline, stop, slide down the incline, and collide with 94eudro7o;c w M again?    kg (Let A represent mass m, and B represent mass M.)

  The gravitational slindsmuv3 :vk32p 3 5tbywgshot effect. Figure 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 The mass of5vswvbd :tm 3u3ky32p 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