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

1#

What is the SI unit of i 5 cwi-o(44z+ts2b zqf7ey pgmomentum?

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 becauseja d+89 hcggn0zpz)0x kx3q00hdgsa+ 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 trackb:kd6s0yi : y; 2jqa 4/wesysg at constant speed. The car is open on top. A large load of coal is suddenly dumped into ss 2 ijkg64yq:asyb yd0e:/w;the 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 4l1ki v apc769jkb:fc nsdrwj814 od3 while sledding on frictionless ice. What happens to the veloci8f ksc7 64v4ado311 9jldnrc:kipw bjty of 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 have equal mass. They are t vpi vl l)v7tpxkqr: /w* gi)2e7b;nv)hrown with equal speed against a wall. The ball bounces back with n ))pnt :brg7xv*ewv ; 7pqv/ki)lliv2 early the same speed with which it hit. The putty sticks to the wall. 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 with a momentum p. 8)/rh wksgyxr)lx ,-z How would you represent its kinetic energy in terms of these two qzsyhxrr, /gl)) w8 kx-uantities?

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 baseballkymtg*592 bnoi(1 qkh/ xzdy7 with twice the kinetic energy you gave it in the previous pitch, the magnitude of its mome ig nmbt5 /2 q(oyzd7*1xkkyh9ntum 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 is23-7bt6svepj+pgo6g het8t n terms of momentum.

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 conservation of n(d-giypdro-v;t23 r 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 on a5q7 dbkcvobe5umq4 /h.4 zz6 u 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 staz8hc modq;g0y t: 2x3xtement?

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 tu/:et(vrcwm90 f w o k6z oux8b)0cgp9ruck in a head-on collision. Which of the following statements concern6/ muwo wrut 8b0g)p e99fk:v(x0zoccing the magnitude 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 andgn1al.gve*v 6 the 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 ggve v.n6al 1*greater 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 easzqj8lm3g;1n g) rpvquaw1 /zd 5-egg* t at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces back to the ww m8g51vrzdj a3g-n l)uz;*eq1qgg/pest, and the bowling ball moves very slowly to the east. Which object experiences 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 each oj7w;j -d 9yvsfe(q7pj ther. 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 7qarh;x k1m1zlfe 3* pright at 4.0 m/s. It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which statement is corr r klphaf ;x7zem3*1q1ect?

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 moving at 2.0 mf5 g 5qh*ot,pd )ebz+k/s tackles head-on an 80-kg halfback reoh5qbf z*5 kg,)p +tdunning
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 momentum is conserved, then which qfp5/r3n 2minj *wcy xx6, id2of the following statem 2 i,j/c*xnpnq fixd653 2yrmwents 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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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When is kinetic energy co/xpcyjkvrjx:302v le q:6(gknserved?

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 thzimli 1 /q)*05gvbuvme #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball hi*v/bqzm)mi0 5l vu g1ad 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,/t+qjscwgzq*ejr1 ; of 6.0 m/s collides with a heavy exercise ball at rest, the beach ball's speed after the collision will ber,t; e+ g1 *zjwsqcj/q, 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/s to the right collides in a hengecm;vxi n ge47vhi8a86 )b8hs .kv -ad-on collision with a stationary bowling ball in a friction-free environment. If the 8m v kag8gvine-7n;6c)84vx hes. ibhcollision is almost perfectly elastic, 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 m843fc0ny)imremg:n i /s collides head-on elastically with an identical ball08)y n i4:mfng ecrm3i at rest. What is the speed 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 moving with speed v collides head-on with a very liggg9i yjq//b0ko yhn cf .b-jv0v*9 lp5ht object at rest. The collision is elastic, and there is no friction. The heavy object barel5 g nio-ylb vk0/j9h. f 0y9vpgbj/c*qy 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 moving6qtjo qy75 hpbn d2+:g with speed v collides head-on with a very heavy object at rest, in a frictionless environment. The collision is almost perfectly elastic. The speed of the heavy object 57opd n:y6q b+qjg2htafter 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-olw5)9g3c q gyun with a yellow ball of equal mass moving with a velocity of -2.0 m/s. Ww3cug )5lq9yghat 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 gv/qaf mjlm -*: 5geu8rwkh lf-*/ti- moving with velocity v collides head-on with a very light object moving with velocity -v. The collision is elastic, and there is no friction. The heavy object barely slows down. What is the speed of the light object afterfwiq *hr8-fe k 5algglv:*m/--t/muj 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 collision, if the momentum is conserved, then w.p 5ikoez/u.f*oa/trvh+3 ct2 (lqha hich of the followizoa tv+.(qtcf.o5phla* /ik/3u 2herng statements 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 together. Kineticcpenx 74t)) ex 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 right at 4.0 m/s. It collides in a perfectly6z.mpvtpn 1o+ inelastic cop1 mv pt.nz+6ollision 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 lar2:j/ikmc oi8p 6 ri)ijge object and sticks. Which object experiences the larger magnitude of : c/priii2 imj8)okj6 momentum 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 def de7a5j u8r5shqc hgedpucxy *.),x:3lected at a $35^{\circ}$ 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 masses, M and m. Which ofu4 7j b/ngcu* tomhd:e7krzs0 ( -g.)hfchm+t the following statements is false7*r. gh fju:4bg mohuhn)7+sc /tc0zek-td( m?

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 following is a false stpte;cm w/k/z/atement?

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 longz fv;k4y, +3pzl r1gaa flexible rod in order 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, reuj iz dtfv r-;*ag*:r3leases a bomb, which explodes before hitting the r*td:ivafr; z-guj3 *ground. Neglecting air resistance, the center of mass of the bomb fragments, just 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. The collisi;z, 5y8s,scvna e2yg oa n2l(zon was completely inelastic and both cars quickly came to rest during the collision. What is true about the velocity of thvsc8azogn 25,;,nlyye sa z(2is 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 system of partic(pcwsvr7*6 wor; o1yc7x9rqeles.

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 traveli0 kyobuyw+7e ft367f l4;vnsizrfa : 3ng at 35 m/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 c ,g hmz -vopace.k. kz.m:ym/91n9hyj2*yysmomentuzsygky-..p 2y ov9/haccn1myj kh,z9m:m*.e m?

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 is dropped from a he1zdbry.li/38vs(v+ x56qu eow m xl7qight of 12 m. Its momentum when it svbzr8osw.ly6ldm1i537 xvu q( +q/xetrikes the ground is

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 perpendiculj0ln6z5lt )r9dcl ne 7ar to each other. One moves with a speed of 25 m/s due north and the other moves a el57n6c j90)zrtlndlt 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, traveling horizontally at 30 m/sbg2gnzdi0e l0b y j8-/rr3 x)w, strikes a wall and rebounds at 24 m/s. What is the change in thew/ 0y8gb3 02bnl) jg-r zeirxd 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, initially moving at a speed of 12 m/s, iswo fbp4ly *)4o struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. What is the chl4w* pfyoob )4ange 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 baseball) is placed on a froi-uaty9hs lgq8r )d5,*p9yvz zen pond. The machine fires a 0.40-kg baseball with a speed of 35 m/s in the horizontal direa r* t9gl,8s)d-pq9 uyziy5vhction. 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 outsura x0l)c2 1/l yogpn:yg u1)eide the space capsule and is stationary when the tether line breaks. As a means of returning to the capsule he throws his 2.0-kg space hammer 1 x rlgay /u:1c2y))ple0u ngoat 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 .5fpwzmx,: iz 5.0 kgm/s approaches head-on a large object at rest. The small object bounces straight back with a mome,5 pwz.mxiz:fntum 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 frieresls*6, u; cmnd (40-kg mass), who is standing still, with open arms. As you collide, while holding each other, with what s6s ul ;srem*,cpeed 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 along lyx d2+kr39lg6dqdo 8kmmj +0a level, straight road at a speed of 6.0 m/s. It collides directly with a stopped motorcycle of mass 20krd6l d2 mx+y 3kl8m+doq g90j0 kg. What is the 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 m/s runs in1*4ndc4tee1el:b : zwgs1/ ztuovu, sto the rear of a stopped car that has a mass of 1500 kg and thst,obtu4gul/e d41e1v:*zs ncw ez :1ey stick 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 15,000bqi 98n ,qzaw7 kg, is allowed to coast along a level track at a speed of 2.0 biz,nq7aw98 qm/s. It collides and couples with a 50,000-kg second car, initially at 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 with negm+ u7iya*nr r+ligible 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 tr* ai+n7+y umrhe 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 the rate of 0.80 m/s (with respect to2 jpwcf(0bgz9q (,5, maxjfth the log).c jxtm(p9b qz,w 5ff 0hjga2,( With what speed does the log 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 o ,zedk3e)v(u kl3mjq 2u 1h8ybn an object. The force suddenly increases to 15 N and acts for one morukq33,eby8 2 j) mvuel1kz d(he 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-kg object. Whqua1t:ov )jbn(r+/l c mm d03hat is the object's cha /(0 v j:mh)1nbco3+qlutardmnge of velocity?

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 the right at 30 m/s, collides with w1t:xo3m jt;fa brick wall and comes to rest in 0tj;mftwx :o 13.20 s. What is the average force the car exerts on the wall?

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 f)i9px23 g3 537rqmvy9yo3y adzy ant(fwqr 0the ball back along the same path, and at the same speed. If the bat was in contact w3yayzi2a)r g57m qo 9fyvn3pfq309( t3dyrx with 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 dropped onto a table top. The spelwg*scbraay2 : ua-: 0 punc*/eds of the ball right before and right after hitting the table top are 5.0 m/s and 4 *gcnrb*-:/ lapw0:sa2auucy.0 m/s, respectively. If 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 k )i5djw4psfy1 t:v nz*g, fires 50.0-gram bullets, with a muzzle velocity of 750 m/s, at the rate of 300 rounds per minute. What is the average force exerted :s 45p1yj)tdv fzwi*non 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 building gaj/0y- gm.n r x.uae*in order to knock the door down. This requires a /.erx*0.g- j gmyuna aforce of 1000 N. If the hose delivers 40 kg per second, what is the minimum velocity of the stream 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. Ito7kv;1x ,c:lwnnoy r /2np7p9muj+l zsf)xq4 falls 3f j polpms2lx:77nnw94 , xvu+zn;yrq)k o/c1.20 m to the ground. 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 velocity of 40 m/s after 3.0 s, wh -rbxe *gc23hken fired straight up. What average thrust forc xb2rc*he3-k ge 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 xch3h z4p,8kvnzz 9a3o0-etkinitially at rest in outer space. They push each oth- k30 voxh9c8zn4e akh tz3zp,er apart. What is their separation after the lighter 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 m/s. It collides in a perwpdvj :+,0ptmtf d 7imv:k z-/fectly elastic collision with a 6.0-kg object moving to the left at 1.0 m/s. What is the tota dv im:v,t/t7fwkz0pj +-p :mdl 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 ma-n o.*-c+tlcelfscan)8 xo7e kes a head-on elastic collision with a 0.15 kg object initially at rest. Whatc*8o+lc-s-n 7 ltce f neoxa.) 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 ,on+3h.u3nldxug e,za 1.00-kg block at rest. The bullet 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 3u. hgu 3+oldn,,nexzthe 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 rest, is struck head-on by 3+ f/d25:wk5rjdew (dkoe t3* 9lihq gcdkgn4 an alpha-particle (which consists of 2 protons and 2 neutrons) moving at speed v. If the collision is completely elastic, what speed will the alpha-particle have after the collision? (Assume the neutron*3ek9 w:(3h edd4q5tijw/gk c fn2 d+rlokdg5'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 ballbi9775:zg m+l t vqhsmlzer70 of mass 100 g. The7:zb0 r l795q hs7zeglitvm+m collision 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 eaonnvszvt -i, l m03p-4st with a speed of 3.70 m/s collides head-on with a 200 g ball sitting at rest. Tt-3,0v- ilsz nmn ov4phe 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 speed of 5.0 m/s. It colliddvqmpy3 : a;r xzd1(08vj*votes head-on with a 3.0 kg mass at rest. If the collision is perfectly inelastic, what is the speed of the mav0oz 3;jxvy*ad qp8mvr1 (t: dsses 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 collides head c6nhp pw0k-o9-on in a perfectly inelastic collision with a stationary 2.0-kg mass. How much kinetic energy is lost during thi-co96kpn 0h pws 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 h,ucpeole-h(3g z g 5+velocity v, strikes a parked station wagon, who's mass is 2m. The bczeeh(l5 u-g p,g+ho3umpers lock together 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 gm(y8t *ohc,uenw n,)direction buries itself in a 2.4-kg block ofoh u, new,mg( t8)*cny wood a rest directly above it. As a result, the bullet/block combination 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 3000-kg car ty fmcu,1h,b -araveling at 60.0 km/h south. The two cars stick together after the collisio,1mhfab, u- ycn. (See Fig. 7-1.) What is the speed of 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 car tra8g; rhf*/9xwqky l +mgveling at 60.0 km/h south. The two cw hyrg/+g 9*8mx;kql fars stick together after the collision. (See Fig. 7-1.) What is the direction of motion of the cars after collision?

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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 aorv:.q+ z2,a/a: (gmczxa zfq 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 magnitu( qaax.:2zf: ,zgmz vc/ra q+ode of their combined momentum after the collision?

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 toward the 6x(.u , zzdpcru4dblt./t.xtNorth with a velocity of 4.0 m/s. I4rp.t6z /.xbu, dt utlxcdz.( t explodes into three fragments: 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 o3)5)q:orpo)hngcc hf )*ldd7o0qx j omc.xc 4 rigin, and a 10.0-kg mass sits at x = + 21.0 m. Where is the center of0)d3m )x*p)goho c crj7x:ocq.ho d lc f)4qn5 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 a two-particle system is ce0lh42hss/wl e;czaso ;* x; 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 h 40o2z cxh*swc ;a;;lee/sl smass of 3.0 kg?

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 positione wt6c 0uz):cerd as follows: 2.0 kg at (0, 0), 2.0 kg at (2.0, 0), and 4.0 kg at (2.0, 1.0). Determine the coordinates of the c c6c0:rw uzte)enter 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, 2.0 kg, h:d,ev7d7uf fhmf33 2 cs t5okand 3.0 kg, are located at (0, 0), (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectively. What s3 hcv ,dd7 o7f:5mut2hf 3kfeis 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 posjv;x0bxub iz7 a82nt/ itioned at (0, 8.0), and a 1.0-kg mass is positioned at (12, 0). What are the coordinates of a 4.0-kgbz2utb07; 8 vi jnx/ax 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 leg including the:vnlrk- 5rk k+ foot when the leg is stretched straight out. Assume -k +rv:n5rklk the person is 1.60 m 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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