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

1#

What is the SI unit of momentum? sav,+8clj 9o9.feujli(0chf

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 cshmyd t78;kak.(i8isvm9-j ykt8 oy *annon will recoil backward because 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 ra- t 0idlc+aaq zbluxm8-8-g *nilroad track at constant speed. The cal x-b i8lquzgn dcam+8a*-t -0r is open on top. A large load of coal is suddenly dumped into 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 while l5v gs(s,mh d-sledding on frictionless ice. What happens to the velocity v h,l-mdg( s5sof 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 thx -:xmq-vq0 ngeq*lwy,k3u3s rown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which objects experiences the greater momentum usx3qlne-k0qy3- wvqg: * , xmchange?

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 m-r 0u58 ygswsy9fbp)4 aah7yjoving with a momentum p. How would you represent its kinetic energy in terms of these two quanti75aspjasy-)y08hr yfgb9u w4ties?

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 l2ft 64nlcii7gave it in the previous pitch, the magnitude of its momentum iln74c t2i6l fis

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 bo )65;jyoiuzh z/3hd(bcq3q 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 conserep :7g9 udl b9:byahy-vation 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 on a Force versus time (F vs. t) graphwty61g (distd3z 8or6 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 statem 9hofjl 9rg(9r qio:y7ent?

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 thtaq* es:rx-0tluo8-;n t zcg9.hh fp9e following stzac;st:tfgh . -9e0-o n*t8huprxlq 9atements concerning 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 and tkfgs 9i n33eu q(od20ahe other blue) are dropped from the same height, and rebound off the floor. The red ball rebounds toqdok3u(0i92fe3n gsa a higher position. Which ball is subjected to the 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 east at a speed of 4 m/s, collides with a cjwk16d /gm h uus)mzhd -(99ikl 6mz)stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences th61 kmi9/u 9 c(d mml6dz-huwgjhz)sk)e 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 other. Linear momegxz vze;1;0w lntum

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. z;isie2hx q,2zl 2v; oIt collides head-on with a 6.0-kg object moving o 2hieq2l2i,z ;s;zvx to the left at 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 moving at 2.0 m/s tackles head-on o2artp3, - jftly; xk;an 80-kg halfback running -lt apky3rf;2t,ox;j
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 i5tr :p1p8 vwnhs conserved, then which of the following statemen tnwhv81:5p prts 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 con9uviu oee c1a *1+soh4served?

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 the #5 buc)*+b n rvp0:wrhb7p e*c0xqall moves away with the same velocity p**cvh+ rwux0bpbqc)e n70 :ras 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/qb5 s lpnb6 z8uuk-y;9pzac/:a de17qs collides with a heavy exercise ball at rest, the beach ball's speed after the collision will bae/9c bz l upq86;bk1z:ayus7p5 -ndqe, 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,wk5xw,h5iq6/x nb eq 3.0 m/s to the right collides in a head-on collision with a stationary bowling ball in a frictihi,bq,n x5w5/xkqw6e on-free environment. If the collision 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 m/s collides head-on elasticallye9 u8 b*5zf.xg ndjjd6 with an identical5gj6*z8d dxj.eu 9bf n ball 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 luyqf*dd 1 57jbight object at rest. The collision is elastic, and there is no friction. The heavy object barely slows downd*f7qjy d5 bu1. 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 collides head-on with a very hea 3kahvik0ax. :vy object at rest, in a frictionless environment. The collision is kh.vkx3 iaa0:almost perfectly elastic. The speed 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 cod1p4lri ldgeg1sd7y;0uf335mo jkk)llides head-on with a yellow ball of equal mass moving with a velocity of -2.0 m/s. What is the velocity of the yellow 5g4km3 yfd11l;ed7 )usdj3kipgor0 lball 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 hea/rzhdw 5b wd 2g-8q)rhy;(jx ad-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 ligyqzwhdahxg) ;5/r8 w - d(2rbjht 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 collision, if the qki(/umlo 3 +gmomentum is conserved, then which of the following statements is trgi/ +l(okm 3quue 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 stickf 7 u1yvsp( yxhr()9je together. 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 right at 4.0 m/s. It coid7:jm. y pwdhw g)d5efmcz7)m y1c (*llides in a perfectly inelastic collisiozd .y pwgi7w:cc1myfmj(eddm*5)h ) 7n 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 large object and sticks. Which object experience i))+b+hjl: vs j/txzqs the larger magnitude of momentuqjjz ) v+ s/:+tlxhbi)m 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 #9khi l:wm+xuaq3; t,/g ball and is deflected 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 of the following statementesx.y r-h0c x0gvb*d,s is false?ec0.b ds0gx,-v hx*ry

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 statebc2c 4-d(psnm ;plf8k(sg b*sment?

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 w :sqbpdxu f ,b)tv9a24ith a long 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, releases a bomb, whis 6kb xrp1o;.f5a0nhtal9 / orch explodes before hitting the ground. Neglecting air resistance, the center of mass of the bomb fragmtaosh1.;p0xo 9frb lr an 6/5kents, 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 collisby1cj 2q*a6 psion was completely inelastic and both cars quickly came to rest during the collision. What is true abouta1s6 2yc *qpbj 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 syste-qxsaan;s)0 d m 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 travmw 4f0- alg;pbkol73 deling 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/s7y9bvmiwbn y 7-z1j,m . What is the magnitude of its momen, 1mbj-97nyzi7 ymvbwtum?

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 height of 12 m. Its momentum when ek2v k,x gk-ysox4k7kuug65;it strikes the groundg g7ys5k-2k4 ue6,;ku xvkkxo 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 perpendicular to each other. One moves wia7m;daz qx 0)zth a speed of 25 m/s due north and m;)azd x qaz70the 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, traveling horizontally at 30 m/s, syr xw5ik83 m:vtrikes a wall and rivy8:mw5xk3 rebounds at 24 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, initially moving at a speed of 12 m/s, is struck by v.lo9zz6rd6 ra racket causing it to reboundr6dzor69v lz . in the opposite 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 baseball) is pfn hy)pk1 c85:p49xi k;( rsmiwqy5qulaced on a frozen pond. The machine fires a 0.40-kg baseball with a s 5:rm8i)hk9; pw4cks q xu(pfy1q5n yipeed 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 capsule and is statidc:dqk;m t ,6vonary when the tether line breaks. As a means of returning to the capsule he throws his 2.0-kg space hammer at a speed of 14 m/s away from the capsule. At what speed does the astronaut move toward the cav tq;:cdm, kd6psule?

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 5.0 kgm/s approaches head-on a large object :n3k1v;ho/21upqigm.:jub k* q jdjb at rest. The small object bounces straight b;2 1qg:qbik* .vjuhod k/jb pn: u31jmack 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 gre7p afju/sqc. 3et your friend (40-kg mass), who is standing still, with open arms. As you collide, while holdif/ c3j7apsq .ung 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 moved dvo3:ypa 52p* mphw4s to the right along a level, straight road at a speed of 6.0 m/s. It collides directa3:pvpd2 y pomd*5h w4ly with a stopped motorcycle of mass 200 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 into the rear of a stopped car that(rj juk sypp9zh/ 8awi2.jo25 has a mass of 1500 kg and they stick together. What is poshu2i./wak2r 9 y(j5zj 8pjthe 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 15,000 kaji *,h8isdpr28 pr/ gg, 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 rest and with brakes re ,igraj8*p irdh2p8s /leased. 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, rollomhazz7kv4 g-b te .-9 n)6;lxlqt ea1s with negligible friction on a horizontal tre)x-l-;6 .znz k7 t9qh1agm lavt 4eboack with a speed of 10 m/s. A 70-kg stunt man drops straight down a distance of 4.0 m, and lands in the 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 ok36 ce5t 1s* .kdal6wimqzbc5f 0.80 m/s (with respect to the log)6d cwt1.3lk q6 5as* ibce5kmz. 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 on an object. The force suddenly increases to p*9r2cj y oms+0yup /z15 N and acts for one more second. What impulse w9m2os/pu +cyyp* zr0jas 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 fq9- 4twf11 cjy3xwrcl or 2.0 s on a 6.0-kg object. What is the object's chang-qy4r91cl c xtf3 w1jwe 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 tuelbao6 l// ut+,y-rwx6v:;pt/uat xo the 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 wall wl/-x vauu;:6 o+lty 6//xpubr,atet?

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 p z:7yc1 w+g -j07fxkno-cvbfwa1fkr*itched to you at 20 m/s. You hit the ball back along the same path, and at the same speed. If the bat was in contact with the ball for 0.10 s, what is the magnitude of the average rg 1k-bccj-7f*xfkw7ynzw: +vfo 01a 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 speeds of the 66ojffdmp23 vz/ (xmg(hvww) ball right before and right after hitting the table top are 5.0 m/s and h3 2vf)dfx(v w(j/gz6wmom 6p4.0 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 kg, fires 50.0-gram bullets, with a muzzle cumt;8mnqwh c mru711i5- mh733acrh7w ky y /velocity of 750 m/s, at the rate of 300 rounds per minut 7 7mc mk3yh7qa3nmh8tcw wr 1/uir h1y5u;m-ce. 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 doorm.;7)z qiq jrtc3g kd/ of a burning building in order to knock the door down. This requires a force of 1000 N. If the hose delktq3zm;) 7 rqi jgdc./ivers 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 mpl tm)cy -d5b,inute. It falls 3.20 m to thb mdc)y-l5 ,pte 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 ve)k(na7ik j8 tz;u;tb1t7 ki adlocity of 40 m/s after 3.0 s, when fired straight up. What average thrust force does ik)k in1kt8 a 7z(juadtt7;b;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 oute k3ypm 1vl./ler space. They push each other apart. What is thei1m3yp /ev.llkr 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 wuwvnq01 li8 7ql9h2h4 tjyst xw7;8nsith a speed of 2.0 m/s. It collides in a perfectly elastic collision with a 6.0-kg object movinhx;7 l0 2 v91wnjsshtwq8 i7 q8yn4utlg to the left 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 directiogqrj62+ (ln0d 9u20 0 bsklqgh.capjln makes a head-on elastic collision with a 0.15 kg object initially at rest. What is the final velocity of the 0.10-kg object after colljsj0cq(pku l60 2.ld g 2b9rl+qg 0hnaision?

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 f hi (*ipgryo,:ired into a 1.00-kg block at rest. The bullet emerges (the bullet does not get embedded in the block) with half of its original,i*ir (yop:hg 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 rest, is struck head-on by an alpha-particle (which coaep;;z3)lt cmzw5th ,nsists of 2 protons and 2 neutrons) moving at speed v. If the collision is completelw ht, c;;tm5ep3 )zzlay elastic, what speed 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 coll4 /3ppxc niv.iides head-on with a stationary ball of mass 100 g. The collision is elastic. What is the speed of each ball immediately after the collisio i3.cnpvx4/ip n?

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 east with a speed of 3.70dca85 k*vro )srtc j+( m/s collides head-on with a 200 g ball sitting at rest.r+8rdct (k*ja5cv) os 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 speed of 5.0 m/s. It collides head-ove 6z,dtr(mv 1f/zof+ .hk6tln with a 3.0 kg mass at rest. If the coo,fd6hft6/. m +tz( kv rlvez1llision is perfectly 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 ea8:e l9v7hhall d1vsfn imx 1fkj89*3n st at a speed of 4.0 m/s collides head-on in a perfectly inelastic collision with a stationary 2.0-kg mass. How much kinetic energy is lost7ds h8:l1fkvxm3jn819i fnahvll*9 e 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 parkzk0 eo.f0ic 1oed station wagon, who's mass is 2m. The bumpers lock toge1ozo0i .e kc0fther 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 my4 ezpi0;fla0*c qvt ./s in a vertical direction buries itself in a 2.4-kg block of wood a rest directly above it. As a rlp 0.;i0 c4*q fatyzveesult, 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 30005*zqiph/vo2 j dzbx 7:-kg car traveling at 60.0 km/h south. The two cars stick together after the collision. (7v qbi :/p*joz2d 5zhxSee 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-kg1a-si)qcy3 jpi 14-gsmrdc2q car traveling at 60.0 km/h south. The two cars std1g r-cq2) i4s imy3ajc -1psqick together after the collision. (See Fig. 7-1.) What 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 a level frictionless surfa3cll27i a:) jaeku5bmce. Object A moves east with a momentum of 24 kgm/s. Object B moves nb i)ke2a jl7ula :mc53orth with momentum 10 kgm/s. They make a perfectly inelastic collision. What is the magnitude 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 to oko(s(qs3osahi/+ j9 ward the North with a velocity of 4.0 m/s. It 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 wit3+qss(kho a/ (j ois9oh 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 mass sits at x = + 21.0yhj. seayq 4:3 m. Where is the centye4 jy. a:sqh3er 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 a two-particle sqvupu gjk6 nen ,0go/r-. lgu8/wyi)5ystem is at the origin. One particle is located at (3.0 m, 0) and has a mass of 2.0 kg. g-kn8 glj)/q6vw5p, .uguon e/uri0y What is the location of the second mass 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 positioned as follows: 2.0 kg at (0, ma o8(a7 k0k radd8u(g0), 2.0 kg at (2.0, 0), and 4.0 kg at (2.0, 1.0). Dete(rd ag8u8 a(km7 0doakrmine 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, 2.0 kg, and 3.0 hxt znk08v/wwqq510qkg, are located at (0, 0), (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectively. What is the location of the center of mass z wkqx1whqn80v0/q t5 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 62bw kv.7ftfj2z0vfi (0, 8.0), and a 1.0-kg mass is positioned at (12, 0). What are the coordinates of a 4.0-kg mass which will result in tk0v .2 fjftw7i62fbvz he 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 nr 4.s xdg;:guho3a 7z+ yshq(leg including the foot when t+n ygshqux . :r(7g ;od4za3shhe leg is stretched straight out. Assume 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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