Physics Unit7: Linear Momentum - 51fly国际课程 (51fly.win)

1#

What is the SI unit of momentw o*ruq ,yaj4l:,kxk8um?

A. Nm

B. N/s

C. Ns

D. N/m

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When a cannon fires a cannonball, the cannon will recoil backward becausq*g s 9-kfe2x s1ek+wie the

A. energy of the cannonball and cannon is conserved.

B. momentum of the cannonball and cannon is conserved.

C. energy of the cannon is greater than the energy of the cannonball.

D. momentum of the cannon is greater than the energy of the cannonball.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A freight car moves along a frictionless level railroad track a89 hww1;;q rtthpgs, ct constant speed. The car is open on top. A large load of coal is suddenly dumped into theqhs t c1 gr9;wp;,wth8 car. What happens to the velocity of the car?

A. It increases.

B. It remains the same.

C. It decreases.

D. cannot be determined from the information given

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A child falls sideways off a sled while sledding on frictionless ice.j sj 1,fdh7pp7ricc5 7 What happens to the velocity o1idsc,jhp 5 f7c r77jpf the sled?

A. It increases.

B. It remains the same.

C. It decreases.

D. cannot be determined from the information given

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A rubber ball and a lump of putty hi,gkr78-ws. aqhkd2i ave equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the war8s 7 ,i.wikdh k-2gaqll. Which objects experiences the greater momentum change?

A. the ball

B. the putty

C. Both experience the same momentum change.

D. cannot be determined from the information given

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A sailboat of mass m is moving wit x7qf n8gpqesxw5f5 lq (u:*;qnl 6nm7h a momentum p. How would you represent its kinetic energy in terms of thesl:gmfn8 u n6;x5n5lq7qex(s pwq 7*qfe two quantities?

A. $p^2/2m$

B. $\frac{1}{2} mp^2$

C. $mp$

D. $\frac{1}{2} mp$

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you pitch a baseball with twice the kinetic energy you gave eds/ha j004ea08e+vn6bfdv y:si 2zrit in the previous pitc/ 8fyr2ns 4e0:zsddv6j0eeh+a0i vba h, the magnitude of its momentum is

A. the same.

B. 1.41 times as much.

C. doubled.

D. 4 times as much.

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8#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State Newton's second law in terms of momentum.7 2f+n qv+qorn

该题自我估分: (必填) (满分:1.0分)

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9#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conse 6,zm g;* k8umugpzwr8rvation of momentum.

该题自我估分: (必填) (满分:1.0分)

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve o9aloncsh ) h6(l7edy5n a Force versus time (F vs. t) graph represents

A. impulse.

B. momentum.

C. work.

D. kinetic energy.

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Which of the following is an accurate statemcr y nid08 m3v60ert1rent?

A. The momentum of a projectile is constant.

B. The momentum of a moving object is constant.

C. If an object is acted on by a non-zero net external force, its momentum will not remain constant.

D. If the kinetic energy of an object is doubled, its momentum will also double.

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A small car meshes with a large truck in a head-on collision. Which of the n i(td8zs/e( p 3j1zjifollowing statements concerning the ma1np ez/ij( 83dit( szjgnitude of the average collision force is correct?

A. The truck experiences the greater average force.

B. The small car experiences the greater average force.

C. The small car and the truck experience the same average force.

D. It is impossible to tell since the masses and velocities are not given.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two equal mass balls (one red and tk 0,w.1wvixxw p.(yh whe other blue) are dropped from the same height, and rebound off the floor. The red ball rebounds to a higher position. Which ball is subjected to the gr.wy v.,kxhxi(1www 0peater magnitude of impulse during its collision with the floor?

A. It's impossible to tell since the time intervals and forces are unknown.

B. Both balls were subjected to the same magnitude impulse.

C. the blue ball

D. the red ball

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A Ping-Pong ball moving east at a speed of 4 m/s, collides with a stationary bona c(5o 5ex7anbhg9 7dwling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experience ax(7a7odeh9 5ngn5 cbs the greater magnitude impulse during the collision?

A. Neither; both experienced the same magnitude impulse.

B. the Ping-Pong ball

C. the bowling ball

D. It's impossible to tell since the velocities after the collision are unknown.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects collide and bounce off+ok v.pk ,bb)5rli+)4 c8htt dgk7pfz each other. Linear momentum

A. is definitely conserved.

B. is definitely not conserved.

C. is conserved only if the collision is elastic.

D. is conserved only if the environment is frictionless.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg object moves to the right at 4.0 m/s. Iklxc z(9w(bkih:b v .1t collides head-on with a 6.0-kg object moving to the left a bhk1. : k(v9cibxw(zlt 2.0 m/s. Which statement is correct?

A. The total momentum both before and after the collision is 24 kgm/s.

B. The total momentum before the collision is 24 kgm/s, and after the collision is 0 kgm/s.

C. The total momentum both before and after the collision is zero.

D. None of the above is true.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-kg football linebacker me y--rt um-)adoving at 2.0 m/s tackles head-on an 80-kg halfback rur)-aeud- ym- tnning
3.1 m/s. Neglecting the effects due to digging in of cleats,

A. the linebacker will drive the halfback backward.

B. the halfback will drive the linebacker backward.

C. neither player will drive the other backward.

D. this is a simple example of an elastic collision.

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

In an elastic collision, if the mome;kc;p w(ex f23;aamzantum is conserved, then which of the following statements iszap;;;x mc kfeaw 2a(3 true about kinetic energy?

A. Kinetic energy is also conserved.

B. Kinetic energy is gained.

C. Kinetic energy is lost.

D. none of the above

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When is kinetic energy 8jugx,e 8,h8w20 qrqy k wh5njconserved?

A. in elastic collisions

B. in inelastic collisions

C. in any collision in which the objects do not stick together

D. in all collisions

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

In a game of pool, the white cue ball hits the #5 ball and stops, while tx .m9p 7p kkoj;isv40ohe #5 ball moves away wp;ovjx.kko pim 094s 7ith the same velocity as the cue ball had originally. The type of collision is

A. elastic.

B. inelastic.

C. completely inelastic.

D. any of the above, depending on the mass of the balls.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When a light beach ball rolling with a speed of 6.0 m/s collides with a he/a9 inzp:v4bit9swco /z (do+avy exercise ball at rest, the beach ball's speeaii/(p/4 bwt zs:9cd+z9 vonod after the collision will be, approximately,

A. 0.

B. 3.0 m/s.

C. 6.0 m/s.

D. 12 m/s.

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22#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A golf ball traveling 3.0 m/sgq 2mj1 +smd6u to the right collides in a head-on collision with a stationary bowling ball in a friction-free environment. If the collision is almost perfectly elastgud+12mqjs6 m ic, the speed of the golf ball immediately after the collision is

A. slightly less than 3.0 m/s.

B. slightly greater than 3.0 m/s.

C. equal to 3.0 m/s.

D. much less than 3.0 m/s.

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A rubber ball with a speed of 5.0 m/s collides head-on elastically with a 9;r6 -riu6 70f twjmu9 albl;i+lk gu7)ixeyin identical ball at rest. What is the speedu)w;lk eii9fla07t7 u rm-j9+66i ir;bu xlyg of the initially stopped ball after the collision?

A. zero

B. 1.0 m/s

C. 2.5 m/s

D. 5.0 m/s

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very heavy object -vhgt;w6u ir4s+ mkuf4 jvj.4moving with speed v collides head-on with a very light object at rest. The collision is elastic, and there is no friction. The huw-hj4t+g kvjru.imfsv64 4; eavy object barely slows down. What is the speed of the light object after the collision?

A. nearly v

B. nearly 2v

C. nearly 3v

D. nearly infinite

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very light object moving with speed v collidzpbhp jz03 whmq68w/5ox 9,pp es head-on with a very heavy object at rest, in a frictionless environment. The collision is almost perfectly elastic. The sp/93q 6hpop0pjw hzpxmz,w b58eed of the heavy object after the collision is

A. slightly greater than v.

B. equal to v.

C. slightly less than v.

D. much less than v.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A red ball with a velocity of +3.0 m/s collides head-on with a r -;u*sxxyx98945 0.ljmh mnf ef2fusaz6 mkfyellow ball of equal mass movs8ex-4hsfrf*m 9fx 2zm5fjuyu 6k0a9 ;n lmx.ing with a velocity of -2.0 m/s. What is the velocity of the yellow ball after the collision?

A. zero

B. +3.0 m/s

C. -2.0 m/s

D. +5.0 m/s

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very heavy object moving with velocity v collides headi977.bbqrtgh k6epk dgdg (xm9+x -m(-on with a very light object moving with velocity -v( b7tk.-hrmx9mib7k gx6g pd9qd e(g +. The collision is elastic, and there is no friction. The heavy object barely slows down. What is the speed of the light object after the collision?

A. nearly v

B. nearly 2v

C. nearly 3v

D. nearly infinite

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

In an inelastic collisiibi, i4tt6cyve o x00+on, if the momentum is conserved, then which of the following statemeciet+i06,xyb4t v 0 ionts is true about kinetic energy?

A. Kinetic energy is also conserved.

B. Kinetic energy is gained.

C. Kinetic energy is lost.

D. none of the above

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects collide and stick tog a1pa:pjs dvvw61*w y4ether. Kinetic energy

A. is definitely conserved.

B. is definitely not conserved.

C. is conserved only if the collision is elastic.

D. is conserved only if the environment is frictionless.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg object moves to the ri c,w5re a4)df(uh *ldoght at 4.0 m/s. It collides in a perfectly inelastic collulc*)d r,w5 heo4 fda(ision with a
6.1 kg object moving to the left at 2.0 m/s. What is the total kinetic energy after the collision?

A. $72 \; J$

B. $36 \; J$

C. $24 \; J$

D. $0 \; J$

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A small object collides with a z5m2yphoxz):2 jo bmsin b 9(4large object and sticks. Which object experiences the larger magnitude of momen9 pmos54mzi 2(obbxyh2nz):j tum change?

A. the large object

B. the small object

C. Both objects experience the same magnitude of momentum change.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

In a game of pool, the white cue ball hits the #9 ball and is deflected at a l4xw*9pqfi-m:j9x jlk m0hz9 $35^{\circ}$ angle to the original line of motion. What is the angle of deflection below the original line of motion for the #9 ball?

A. $35^{\circ}$

B. $55^{\circ}$

C. $75^{\circ}$

D. $90^{\circ}$

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33#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two unequal)u56o ,xyehyv masses, M and m. Which of the following statements is false?yy56e,xou hv )

A. The center of mass lies on the line joining the centers of each mass.

B. The center of mass is closer to the larger mass.

C. It is possible for the center of mass to lie within one of the objects.

D. If a uniform rod of mass m were to join the two masses, this would not alter the position of the center of mass of the system without the rod present.

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Which of the followix6vo4qjmtp; elhuf7)xqpp4f:5 aw*: ng is a false statement?

A. For a uniform symmetric object, the center of mass is at the center of symmetry.

B. For an object on the surface of the Earth, the center of gravity and the center of mass are the same point.

C. The center of mass of an object must lie within the object.

D. The center of gravity of an object may be thought of as the "balance point."

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Tightrope walkers walk with a long flexible rod in ordn a7i: s(j77pz wgnce0 .j+pxaer to

A. increase their total weight.

B. allow both hands to hold onto something.

C. lower their center of mass.

D. move faster along the rope.

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A plane, flying horizontally, releases a bomb, which en idm .ub1o 22(srcsw+xplodes before hitting the ground. Neglecting air resistance, the center of mass of the bomb fragments, jus2o(n u ss. i+crd1wmb2t after the explosion

A. is zero.

B. moves horizontally.

C. moves vertically.

D. moves along a parabolic path.

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37#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two cars collide head-on on a level friction-free road.+td /s*c4bs71wgnv;rk6-hm0 numnk f The collision was completely inelastic and bm;7 bd1t4+cg6s/u*fmsn -n rk kvnh0 woth cars quickly came to rest during the collision. What is true about the velocity of this system's center of mass?

A. It was always zero.

B. It was never zero.

C. It was not zero, but ended up zero.

D. none of the above

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38#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State Newton's second law for a systpgnm9hp h 9/(t to)pxn2xdl.p4o 9m t)em of particles.

该题自我估分: (必填) (满分:1.0分)

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the momentum of a 2000-kg truck traveling at 35 m5df gnb1w 5k +*+lpbta/s?

A. $57 \; kg \cdot m/s$

B. $3.5 \times 10^{4} \; kg \cdot m/s$

C. $7.0 \times 10^{4} \; kg \cdot m/s$

D. $7.0 \times 10^{5} \; kg \cdot m/s$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1200-kg ferryboat is moving south at 20 m/s. What is the magnitude of its mobxx(e:b(my 0ll8 p9z / i((hai2uirasma(8(hbeui/0x rxbz9 la2 sl((i yip: mentum?

A. $1.7 \times 10^{-3} \; kg \cdot m/s$

B. $6.0 \times 10^{2} \; kg \cdot m/s$

C. $2.4 \times 10^{3} \; kg \cdot m/s$

D. $2.4 \times 10^{4} \; kg \cdot m/s$

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball of mass 0.10 kg isj xlrw j(tu.2 )(.kovy dropped from a height of 12 m. Its momentum when it strikes the ground i.. vu(k(y) otj2rwjx ls

A. 1.5 kgm/s.

B. 1.8 kgm/s.

C. 2.4 kgm/s.

D. 4.8 kgm/s.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two identical 1500-kg cars are moving perpendicular to each other. One moves wvg.r- s1( yrhoith a speed of 25 m/s due rg1h.rosy( -v north and the other moves at 15 m/s due east. What is the total momentum of the system?

A. $4.4 \times 10^{4} \; kg \cdot m/s$ at $31^{\circ}$ N of E

B. $4.4 \times 10^{4} \; kg \cdot m/s$ at $59^{\circ}$ N of E

C. $6.0 \times 10^{4} \; kg \cdot m/s$ at $31^{\circ}$ N of E

D. $6.0 \times 10^{4} \; kg \cdot m/s$ at $59^{\circ}$ N of E

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A handball of mass 0.10 kg, p/9 pi6zvjowl((gg/ rtraveling horizontally at 30 m/s, strikes a wall and rebounds at 2r9 wj(/gvlopzip6(g /4 m/s. What is the change in the momentum of the ball?

A. 0.60 kgm/s

B. 1.2 kgm/s

C. 5.4 kgm/s

D. 72 kgm/s

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.060-kg tennis ball, initialbsi4, n6uzw qx0-s*hqly moving at a speed of 12 m/s, is struck by a racket causing it to rebound in the oppos nxzw4b0-qus s qhi6,*ite direction at a speed of 18 m/s. What is the change in momentum of the ball?

A. 0.36 kgm/s

B. 0.72 kgm/s

C. 1.1 kgm/s

D. 1.8 kgm/s

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-kg pitching machine (excluding the baseb js d2s,)sjk4zall) is placed on a frozen pond. The machine fires a 0.40-kg baseball with a speed k2 sjsjz4ds) ,of 35 m/s in the horizontal direction. What is the recoil speed of the pitching machine? (Assume negligible friction.)

A. 0.14 m/s

B. 0.28 m/s

C. 0.70 m/s

D. $4.4 \times 10^{3} \; m/s$

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 70-kg astronaut is space-walking outside the space capsb 0jb3 ge2fuzjlvp5 2m v6c*x(q5.unbule and is stationary when the tether line breaks. As a means of returning to the capsule he throws his 2.0-kg spabn6 0jm 5.pc2b2uf3 e lgux5bvv(jz q*ce hammer at a speed of 14 m/s away from the capsule. At what speed does the astronaut move toward the capsule?

A. 0.40 m/s

B. 1.5 m/s

C. 3.5 m/s

D. 5.0 m/s

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A small object with momentum 5:qo fefho*1y5.0 kgm/s approaches head-on a large object at rest. The small object bounces strfe5 qo o*:hf1yaight back with a momentum of magnitude 4.0 kgm/s. What is the magnitude of the large object's momentum change?

A. 9.0 kgm/s

B. 5.0 kgm/s

C. 4.0 kgm/s

D. 1.0 kgm/s

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You (50-kg mass) skate on ice at 4.0 m/s to greet your friend 11 h5*zzgkfe lej+gt:(40-kg mass), who is standing still, wit fe*hze 1gt:jl15+ kgzh open arms. As you collide, while holding each other, with what speed do you both move off together?

A. zero

B. 2.2 m/s

C. 5.0 m/s

D. 23 m/s

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of mass 1000 kg moves to the right aloxdtf1l q 8f:)vng a level, straight road at a speed of 6.0 m/s. It collides directly with a stopped motorcycle of mass 200 kg. What is the 8:t qflxvf1d) total momentum after the collision?

A. zero

B. 6000 kgm/s to the right

C. 2000 kgm/s to the right

D. 10,000 kgm/s to the right

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1000-kg car traveling at 25 +-ib;*ss rmd :k;orh 0n8kbkx s:5fae m/s runs into the rear of a stopped car that has a mass of 1500 kg and they st8nsbo5 s- sehmr;ab0ikkk+ ;:d:f*xrick together. What is the speed of the cars after the collision?

A. 5.0 m/s

B. 10 m/s

C. 15 m/s

D. 20 m/s

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A railroad freight car, mass 1 -bf-vap(as.2cvw.+ uc*qr vi5,000 kg, is allowed to coast along a level track at a speed of 2.0 m/s. It collides and couples with a 50,000-kg second car, initially at*(.v- 2rfwp+ ucc qs.vavb-ia rest and with brakes released. What is the speed of the two cars after coupling?

A. 0.46 m/s

B. 0.60 m/s

C. 1.2 m/s

D. 1.8 m/s

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A railroad car, of mass 200 kg, rolls wiup5we 2gto g 81ts6-jith negligible friction on a horizontal track with a speed of 10 m/s. A 70-kg stunt man drops straight down a distance of 4.0 m, and lands in th-5 gs16tuo2tp8 ie wgje car. How fast will the car be moving after this happens?

A. 2.8 m/s

B. 4.7 m/s

C. 7.4 m/s

D. 10 m/s

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg person walks on a 100-kg log at they;0qj+d a2( x// mgg taajaa *n;nqfr1 rate of 0.80 m/s (with respect to the log). With what speed does the log*a xgjra; y+0amdj2a f1(ng qtna; /q/ move, with respect to the shore?

A. 0.24 m/s

B. 0.30 m/s

C. 0.48 m/s

D. 0.60 m/s

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-N force acts for 3.0 s on an object.yrwf0v1b.-)o n hod 0c The force suddenly increases to 15 N and acts for one mo f dhyb0wv)o0o1rnc .-re second. What impulse was imparted by these forces to the object?

A. $12 \; N \cdot s$

B. $15 \; N \cdot s$

C. $19 \; N \cdot s$

D. $27 \; N \cdot s$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A constant 9.0-N net force acts for 2.0 s on a 6.0-kgu8nlpl x6 sc+- object. What is the object's change of ven-6 +c8pusllxlocity?

A. 3.0 m/s

B. 9.0 m/s

C. 27 m/s

D. 110 m/s

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2000-kg car, traveling to t4kxsi/0sln4a nlo2b+ he right at 30 m/s, collides with a brick wall and comes to rest in 0.20 s. What is the average force the car exerts on the walklb 20n+s44a i/x lsonl?

A. 12,000 N to the right

B. 300,000 N to the right

C. 60,000 N to the right

D. none of the above

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg softball is pitched to you at 20 m/s. You hit the bamje oq q0ynk824 )oqq+i/4;kmw 3iypn ll back along the same path, and at the same speed. If the bat was in contact withm43q+iim q0yn42n /wqje)8p k;k yqoo the ball for 0.10 s, what is the magnitude of the average force the bat exerted?

A. zero

B. $40 \; N$

C. $400 \; N$

D. $800 \; N$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.10-kg ball is droppedg+r7v x u28, ckkani y3la:ax+ onto a table top. The speeds of the ball right before and right after hitting the table top are 5.0 m/s and 4.0 m/s, respectively. Ifx+:2+ ianvgucak k a r,7l8x3y the collision between the ball and the table top lasts 0.15 s, what is the magnitude of the average force exerted on the ball by the table top?

A. $0.67 \; N$

B. $1.3 \; N$

C. $3.0 \; N$

D. $6.0 \; N$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A machine gun, of mass 35.0 kg,vif*k 8n7)ktgd7uvip -p y b 504px0vs fires 50.0-gram bullets, with a muzzle velocity of 750 m/s, at the rate of 300 roun* -0kx)47pvbv 0is7 dppt8vig5yfnk uds per minute. What is the average force exerted on the machine gun mount?

A. $94.0 \; N$

B. $188 \; N$

C. $219 \; N$

D. $438 \; N$

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A fire hose is turned on the door of a burning buildil ;f; e8: dodo6y*zsfnng in order to knock the door down. This requires a force of 1000 N. If the hose delivers 40 kg per second, what is the minimum velocity of the stream ; nofl ;*6dyz8sfd:eo needed, assuming the water doesn't bounce back?

A. 15 m/s

B. 20 m/s

C. 25 m/s

D. 30 m/s

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Water runs out of a horizontal drainpipe at the rate of 120 kg per minute 4)6nv4yjwn rt+bd-bd . It falls 3.20 m to the ground. vnw-t jyd6) nrdb b+44 Assuming the water doesn't splash up, what average force does it exert on the ground?

A. $6.20 \; N$

B. $12.0 \; N$

C. $15.8 \; N$

D. $19.6 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, of mass 0.12 kg, achieves a velocilekmu(a12kv.a:qf; 8p.e9exzz 8 sp ggn 47klty of 40 m/s after 3.0 s, when fired straight1qkeull:k89 p .n7(g 4 ;a2xag8mze p.sezfvk up. What average thrust force does the rocket engine exert?

A. $1.2 \; N$

B. $1.6 \; N$

C. $2.8 \; N$

D. $4.4 \; N$

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two astronauts, of masses 60 kg and 80 kg, are initially at rest in outejhe*b-e q5 et8r space. They push each other apart. What is their separation after the light*eeb tejh5- q8er astronaut has moved 12 m?

A. $15 \; m$

B. $18 \; m$

C. $21 \; m$

D. $24 \; m$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg object moves to the right with a speed of 2.0 * q-;pbomuavjn(.j /o-g 8atnm/s. It collides in a perfectly elastic collision with a 6.0-kg object moving to the legq-jp *n .a -/jou8;v(tobmn aft at 1.0 m/s. What is the total kinetic energy after the collision?

A. $9.0 \; J$

B. $6.0 \; J$

C. $3.0 \; J$

D. $0 \; J$

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.10-kg object with a velocity of 0.20 m/s in the +x direction makes a head p s,zzwhlt/hc p 9le9(o-iu41-on elastic collisi/z4t-lop1 9z9swi h(,pulce hon with a 0.15 kg object initially at rest. What is the final velocity of the 0.10-kg object after collision?

A. -0.16 m/s

B. +0.16 m/s

C. -0.040 m/s

D. +0.040 m/s

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at raqo: mi**pr v8est. The bulletmri*qv pa:o 8* emerges (the bullet does not get embedded in the block) with half of its original speed. What is the velocity of the block right after the collision?

A. 1.50 m/s

B. 2.97 m/s

C. 3.00 m/s

D. 273 m/s

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A proton, of mass m, at res8kao,+ 9 rypqqt, is struck head-on by an alpha-particle (which consists of 2 protons and 2 neutrons) moving at speed v. If the collision is completely elastic, what spee9r+ayo,8 k pqqd will the alpha-particle have after the collision? (Assume the neutron's mass equals the proton's mass.)

A. zero

B. 2v/3

C. 3v/5

D. 5v/3

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-gram ball moving +10 m/s collides head-on with a stationary ball of m ,cop.tjwwii nl83kq*(f;jk :zt)2p cass 100 g. The collision i.pfj3q tnlc;k )w 8c2zwkoji* t:p(, is elastic. What is the speed of each ball immediately after the collision?

A. -3.3 m/s and +6.7 m/s

B. +3.3 m/s and -6.7 m/s

C. -6.7 m/s and +3.3 m/s

D. +6.7 m/s and -3.3 m/s

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69#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

A ball of mass 400 g moving toward the eas elts3j6s ; b. gvnpzflxu3/7/pgy l16t with a speed of 3.70 m/s collides head-on with a 200 g ball sitting at rest.spzlsg; 13xl/e ly73njb66/.f tpuv g The collision is perfectly elastic.
(a) Determine the velocity of the first ball after the collision.
(b) Determine the velocity of the second ball after the collision.
(c) Is kinetic energy conserved in this collision?

该题自我估分: (必填) (满分:1.0分)

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass moves with a sobfzc-(a u.z*peed of 5.0 m/s. It collides head-on with a 3.0 kg mass at rest. If the collision is perfecoa.-f*(z bz cutly inelastic, what is the speed of the masses after the collision?

A. 10 m/s

B. 2.5 m/s

C. 2.0 m/s

D. 0, since the collision is inelastic

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass moving to the east at a speed of 4.0 m/s colli3vfw, p g*0fu+m )uuwzdes head-on in a perfp zv,wu)fm u0+3gw*fu ectly inelastic collision with a stationary 2.0-kg mass. How much kinetic energy is lost during this collision?

A. $16 \; J$

B. $4.0 \; J$

C. $8.0 \; J$

D. zero

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of mass m, traveling with a velocity v, strikes a parked stat zma8gap 9uz+- siwbw bfq39t -jlx(9:ion wagon, who's mass is 2m. The bumpers lock togetherxamqzzb(uj9: gs p t -w3l-a9 98iwf+b in this head-on inelastic collision. What fraction of the initial kinetic energy is lost in this collision?

A. 1/2

B. 1/3

C. 1/4

D. 2/3

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73#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

A 15-g bullet traveling 213 m/s in a vertical directim(jczs vm61:sp, dd7 uon buries itself in a 2.4-kg block of wood a rest directly above it. As a result, the bullet/block combin7 zmps6 d,vum:cd 1j(sation moves vertically upward.
(a) Determine the velocity of the bullet/block combination at the point of impact.
(b) Determine the maximum height reached by the bullet/block combination.
(c) Is kinetic energy conserved in this collision?

该题自我估分: (必填) (满分:1.0分)

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car traveling at 90.0 km/h east collides with a 30 zgl 63zk2u8mh00-kg car traveling at 60.0 km/h south. The two cars stick together after the collision. (See Fig. 7-1.) What is the speed of 8k 6lzhg3uz2m the cars after collision?

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A. 8.33 m/s

B. 13.9 m/s

C. 17.4 m/s

D. 21.7 m/s

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car traveling at 90.0 km/h east collides with a 3000-kg caj, */x. wwkhns;k jcxs8bh*g8 r traveling at 60.0 km/h south. The two cars stick together after the collision. (See Fig. 7-1.) Wsj ;gh bcxjkwwk,.x*s8nh /8 *hat is the direction of motion of the cars after collision?

本题所包含的其它图片:

A. $36.9^{\circ}$ S of E

B. $36.9^{\circ}$ E of S

C. $53.1^{\circ}$ S of E

D. $53.1^{\circ}$ E of S

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects move on 1p q4p-ox:ifk0fzq: wa level frictionless surface. Object A moves east with a momentum of 24 kgm/s. Object B moves north with momentum 10 kgm/s. They make a perfectly inelastic collision. What is the magnitude of their combined momentum after the colliskff1-xzo :w04qiqp :pion?

A. 14 kgm/s

B. 26 kgm/s

C. 34 kgm/s

D. cannot be determined without knowing masses and velocities

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A small bomb, of mass 10 kg, is moving toq1h xlxvihfqh0:4m) 2ward the North with a velocity of 4.0 m/s. It explodes into three fraq: 1f2qil)hh4mvxx0hgments: a 5.0-kg fragment moving west with a speed of 8.0 m/s; a 4.0-kg fragment moving east with a speed of 10 m/s; and a third fragment with a mass of 1.0 kg. What is the velocity of the third fragment? (Neglect air friction.)

A. zero

B. 40 m/s north

C. 40 m/s south

D. none of the above

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78#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg mass sits at the origin, and a 10.0-kg jsz)a tb3yeh h 5cs9z n8w fv,+)1o7uhmass sits at x = + 21.0 m. Wherej h1,oz8esh 3b)nzsca+h) vyuf5w97 t is the center of mass on the x-axis?

A. +7.00 m

B. +10.5 m

C. +14.0 m

D. +15.0 m

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The center of mass of td75w dmgv38pao p2 6ca two-particle system is at the origin. One particle is located at (3.0 m, 0) and has a mass of 2.0 kg. What is the location of the second mass of 3.0 m7w8p 2pvd 3doacg65tkg?

A. (-3.0 m, 0)

B. (-2.0 m, 0)

C. (2.0 m, 0)

D. (3.0 m, 0)

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80#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Three masses are pos3cq+nrn( ns*g mp4 k0fitioned as follows: 2.0 kg at (0, 0), 2.0 kg at (2.0, 0), and 4.0 kg at (2.0, 1.0). Determinfc 3(n*4 nqnk+ srpgm0e the coordinates of the center of mass.

A. (0.50, 1.5)

B. (1.5, 0.50)

C. (2.5, 1.5)

D. (2.5, 0.50)

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Three masses, 1.0 kg ;/:6szesdhc g, 2.0 kg, and 3.0 kg, are located at (0, 0), (1.0 m, 1.0 m), and egds6;s/ z hc:(2.0 m, -2.0 m), respectively. What is the location of the center of mass of the system?

A. (1.3 m, 0.67 m)

B. (1.3 m, -0.67 m)

C. (-1.3 m, 0.67 m)

D. (-1.3 m, -0.67 m)

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg mass is positioned at (0, 8.0), and a 1.0-kg m/q efc)i7 lwl4ass is positioned at (12, 0). What are the coe/ 47fwll )ciqordinates of a 4.0-kg mass which will result in the center of mass of the system of three masses being located at the origin, (0, 0)?

A. (-3.0, -6.0)

B. (-12, -8.0)

C. (3.0, 6.0)

D. (-6.0, -3.0)

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Use Table 7-1 to calculate the position of the CM of a whole le6sw+yb k 3ospy-:f4 w:)ycnjyg including the foot when the leg is stretched straight out. Assume the person is 1.60 fw bojk3+y): w6c-4yy:ps n ysm tall.

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A. 0.20 m above the bottom of the foot

B. 0.32 m above the bottom of the foot

C. 0.51 m above the bottom of the foot

D. 0.54 m above the bottom of the foot

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