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

1#

What is the SI unit of)1gyfb*gi zhewi p123 momentum?

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 dkww 9qdm7zlqy1) o+0because 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 levq3r ml9; g n,q mjtqre0)6(iteel railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped ine6tr0 e,qr 9lqnm)tjq(mg; 3ito 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 sledding on frictionless ice. What haon+w t2/k:c pqojb0hw+l l-7p ppens to the velocity of the sl l nt/ j+wp 2q0+lh-obw7kc:oped?

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 jnmkg9v3+.inare thrown with equal speed against a wall. The ball bounces back wijn3 i.9gm+kvnth nearly 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. How would you represent its jy98w2ioo/ u,uffkk/v pg5)c kinetic energy iy/f, p cgi5ufku8j ) 9k/2vowon terms of these 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 qc)fcgs93bg -the kinetic energy you gave it in the previous pitch, the magnitude 9g -3qgfbc)s cof 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 g-.:upq;o 5 8xpr e.g982yvsa rpwfvf 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 :dikt2 j2 uq;fof 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 verc ;:g0 uee l(72pbipmjsus 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 acg y96cvy,iho8*z-g may ucwz93 ,ho;j curate statement?

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 withhl 07xlxxcm :2 a large truck in a head-on collision. Which of the following statexxc:lml7 h0 x2ments 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 re6 t, 05xkp kiqg8.o.mz1 vwj3k1uhpqzd and the other blue) are dropped from the same height, and rebound off the floor. The red ball rebounds to a higher position..1.kgq,pzkkth x5 3z1p jqwuim 0ov 86 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 spe)ozr 4)twx82 z4keqxfx3vb d ;ed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces bac3)24qx8vtdz r)ob zwxfx4;ekk to the west, 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 ea e:w(fosm ,ro;ch 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. It collides head-onvy8) drxvlaz xh 56,3t with a 6.0-kg object moving to the left at 2.0 m/vl6 dvhxx8z3)rta ,5ys. 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 an 80-kg halfbu; s/o;c6 yqe** njlmyze0k.fp 9nj cp8.7qr aack runningz* e y0 n;7.s*kpqu; qrje6ajlyo8cnm/f. 9pc
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 moment j3kxaweo u0 q(m+sgz0n5iu ,d0+rbj+ um is conserved, then which of the following statements is true about o,x0bd+(a3 w0g n u+rzqsum+05jke ijkinetic 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 conse 4s9xq ib)i/uzgksnxcz807 y( rved?

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 wkv(r7 lj6 kjl/hite cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the(j lrk v/7j6lk 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 s pi.wt4k 5stz)peed of 6.0 m/s collides with a heavy exercise ball at rest, the beach ball's speed aft zk wt4tspi)5.er 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/ cjdzaw zw/-ie0zci2 t /.-ic9s to the right collides in a head-on collision with a stationary/a-cdie. /ii2ctzzj w z9-wc0 bowling ball in a friction-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 heae0t r ttoggh 1(, +l0jii9xe8hd-on elastically with an identical ball at rest. What is the speed of the initially stopped ball after the c(h the0gg l,txet9 +81ii rjo0ollision?

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 7j,drkonswps ngn: tdik h/) 7(u;:.r a very light object at rest. The collision is elastic, and t,h. j:w nor 7krnidg;pk(:dnt )7s/su here 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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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 heapiimd5k4:/eij mn:1 bvy objecti4:p:mijk ni51mbe /d at rest, in a frictionless environment. The collision is 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 veloci; l:4rw4b c7 6fqheb+i (rdrx8eh 7pagty of +3.0 m/s collides head-on with a yellow ball of equal mass moving e q764x 4 e gh bp;hrr7ab8fdrl:+icw(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 head-on with a :asqbxn6f p3zl3pus/ ,ylra*5 /;wf j 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 a:p;sr*/35byslqf /fuaa ,6 xpwjlz3n fter 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, i h zq+0s9ap89w540wy2bxzn p mq fg5qif the momentum is conserved, then which of the following statements is qqw9fyh b z5w qp+0m5nzap28xi09s4 gtrue 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(xd+uc uy83 qb 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 collides in a perfectly pts23bzjag rtgo( 19x/ks+v6 inelastic collision rst9(svjoz3 btk/1 2xap6g +g 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 experien8qr a37ec l9vwces the lavera c7 39lqw8rger magnitude of 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 bdo vpt23jg 6e1all 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 statements ij .he0qj/ -d2xvd 9rvrs false?v-d9rx0. eq r jvh2/jd

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 fals* a is6d2 ,;caxirzb(x )uqjn*e 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 ,, f)s;1ze-d fv2 g,rxe hysunrod 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 horizoi02j bl we a0;rgbjs8x(e 0h;cntally, releases a bomb, which explodes before hitting the ground. Neglecting air resistance, the center of massjs eb;28g bal0;0jhc(0ir ewx 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 7wfg,n8 (je (i qfwru q(e3cy+level friction-free road. The collision was completely inelastic and both cars quickly cfej eq8 gnw((uy+w7 , q(f3icrame 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 fbb90e a hsrf*ik6 ukd.l+z1h 2or a system 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 tru:3k urde9c 9gyck traveling 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 mij; t4.ki6aad agnitude of its mome4kt a6jia; di.ntum?

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 he eztv-o;dl0u1 yg6 qykn usi.6:,vtg ;ight of 12 m. Its momentum when it strikes thee.t;z ;syq,u ykv0:u6 i- ngltgv16do 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 perpendicular to each otherhyv- 9i.h n:ft. One moves with a speed of 25 m/s due north a-yhtf9hin: v .nd 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 kh/ beam gw-vd(c; *;oyud43upg, traveling horizontally at 30 m/s, strikes a wall and rebounds at 24 m/s. What is the change in the momentum of tp;ud/eo43hy *g(-mv cbdua w;he 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 -icl59l njh;bmb ,)m8sjj m kg4w9,b yof 12 m/s, is struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. Wh j- c8b;b,m5lkj9byl i,jnw4 hms 9m)gat 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 placed on a frozen 36f8ds y7nxpp uyhm(0z xer9*pond. The machine fires a 0.40-kg baseball with a speed of 35 m/s in the horizontal direction. What is the recoil speed of the pitchi8 ry37 uydpx0 phs6f(zm*x 9enng 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 s(zfi9 4 io-ybktationary when the tether line breaks. As a means of returning to the capsule he throws z9f-y(o4kibi 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 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 5.0 kgm/s approaches head-on a large ovl vs19-s v*( pgfmovogk85 7d/ pe5clbject at rest. The small object bounces straight back with a momentum of mas1k8pl v5sog9(- p dvl7gec*vf omv5/gnitude 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 (40-ku6vial-d,a.s xi/;tjg mass), who is standing still, with open arms. As you collide, while holding each other, with what speed do you bot ad-v;ui,a/jsti l 6.xh 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 a levemhn8xn(ss0 nmlr ,c13l, straight road at a speed of 6.0 m/s. It collides directly with a stopped motorcycle of mass 200 kg. What is the total momentum (mc3 ,mhn 8xsls1n0 rnafter 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 tj+pd 5zy .2kzxza2l(2 gkqiruxzm: r 7-*,ahqhat has a mass of 1500 kg and they stick together. Wha25rmrax, 2h kgk+u *:lidzjyz(x qp zz 72a.q-t 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, u8z,6xmwp1:lu3;fd(pdg h fa mass 15,000 kg, is allowed to coast along a level track at a speed of 2.0 m/s. It collides and coupzp1u8f dl 6: wph,fd(umg3xa; les 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 wcejj) r 6u78ilith negligible friction on a horizontal track with a speed of 10 m/s. A 70-kg stunt )6j iejuc7l8rman 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 of98b m jd7rihs x.-yfi0v7uz6j )rsdr9 0.80 m/s (with respect to the log). With y b)6.d-x z9r0r d 78u7iijfjv9rm hsswhat 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 f:r yh.jpr sl6-orce suddenly increases to 15 N and acts forr:hlpjsy 6r-. one more 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 ac )sxm 8ise g-zne()f)mts for 2.0 s on a 6.0-kg object. What is the object's change of v8 eenmfz s)-(x i)g)smelocity?

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 a brick wall and of wp)wu *f3q.comes to rest in 0.20 s. What is the average force the car exerts )fqw .p3uf wo*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 pitch: *pz2d,rgkpdb0g sc qp-ht0b5h)adj - szm:.ed 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 force the bat exer20bhj:hzgd-tdskzmaq-: pdr . p 50c p)g*, bsted?

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 tablwiudr*dczr;, 4 7u 5x15fogzfe 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. If the collision between the ball and the table top lasts 0.15 s, what is the magnitude of the average force exerted on w xoru 45z7,uzr;fc5d1fgdi* 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, wlv8/u yqzc yxraab.3 b,.per 1*,:ymnith a muzzle velocity of 750 m/s, at the rate of 300 roun8nuz*a x3by lmp,r..y,v cbyre/ 1qa: ds 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 dooros/ hat),ribxc 3qw3ab1d 8n) of a burning building in order to knock the door)w1tdb / )3sx cq3bnao8h iar, down. This requires a force 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 p8qt*aq(n ebf2z7jp* eer minute. It fa qp8fqz7j* *e2bn(eat lls 3.20 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, w:2 u0ix2gwnda5bmey 8hen fired straight up. What average thrust force does the rocket engine exnudi052em 2xay: wg8bert?

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 azrgx )xz w.csm4 w)/6st rest in outer space. They push each other apart. What is their s sgw 4zzx)cms)x/w.r6 eparation 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. Itn6i*gae (y*ct collides in a perfectly elastic collision with a 6.0-kg object moving to the left at 1.0 m**e g tnya(6ci/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 adwef ivus w+z5 (y51;+pp gvf* 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 colli;e if(w 5 yvf5 +1uspv*pz+wdgsion?

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.flz y2wq(7d5dat, dmqv1 : q4v00-kg block at rest. The bullet emerges (the bullet does not get embedded in the block) with wavd td2fqq7 q5y, l(:m zvd41half 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 rest, is struck head-on by ba6 +z8jxkyc t0rufv+bd+./ uan alpha-particle (which consists of 2 protons and 2 neutrons) moving at speed v. If b8+k+ y+6vf.rjd u tcxu0a/bz the collision is completely 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 collides head-on with a station zg9o k--ix.joary ball of mass 100 g. The collision is elastic. What is the speed of each ball immediately after the -x i9jzo o-g.kcollision?

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 with9.ma w lg0xon),6j zlv a speed of 3.70 m/s collides head-on with a 200 g ball sitting at rv9x .ljg0 wm 6z,laon)est. 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 ce 2wep;;7mu ifollides head-on with a 3.0 kg mass at reime7;2wf ;uepst. If the collision 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 east at a speed of 4.+17de7+df uy mtfzg..xi d wb70 m/s collides head-on in a perfectly inelastic collision wu7+fgdb .d 17 xz+7itdf.e ymwith 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 5: u2dsds6s(ooo2rbevelocity v, strikes a parked station wagon, who's mass is 2m. The bumpers lock together in this head-on inelastic collision. What fraction of the initial kinetic energy is lost in this collision?bs2se s uod2d(5ro:6o

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/s9.td*tnsp7p: vp d 1vo in a vertical direction buries itself in a 2.4-kg block of wood a rest directly above it. As a result, the bullet/block combinationt9pon7: d1 vdtvp.sp* 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?

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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 7s6mofypz h/5v. 0n0x po9gcg 90.0 km/h east collides with a 3000-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 the cars after c7f/n6gvp sz5ym0o xg .cp0o h9ollision?

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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,fefrx tt jb0./)*ynn traveling at 60.0 km/h south. The two cars stick together after the collision.ny. xfe0j, rt/b* )tnf (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 a level frictionless6/lgs4or32h8.rrhgewhcjx)r ih6 v ( surface. Object A moves east with a momentum of 24 kgm/s. Object B moves north with momentumirgrsw le4rxv6r chh6 8(gjhh3o/) . 2 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 mas pgkx g 6abb(k ,s8c.d7w6k0gas 10 kg, is moving toward 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 fr s76kawpkbx 0ga6k(.cgb8 g,dagment 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 b47 ti1fzsb2a at the origin, and a 10.0-kg mass sits at x = + 21.0 m. Where is the cea1i t sbz7fb24nter 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-parcnr8bq760 s gpticle 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 t 0rg6bs7qpc8n he 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, 0), g u-mopqxz.z2sq1oh7c f n)1lls/58d2.0 kg at (2.0, 0), and 4.0 kg at (2.0, 1.0). Determine the coordinates of the centz zx85qfc/ g2s-7sm.opl1hodnl1)u qer 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 kg, are located at (0,8hjx hrw 8sl583udvb ; 0), (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectiv5hsjbv u 8;xw8h lr38dely. 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 masso ;/qw,a (x4psnv5etv is positioned at (12, 0). What are the coordinates of a 4.0-kg mass which will result in the center of mass of the system of tv qetv/;(,x nop45wa shree 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 ofe7:*k)bdy/+ o;x o(pxaxwi ;gpz k.np the CM of a whole leg including the foot when the leg p oek)ogz.wxa *y;xd(bp;+i xpnk: /7is 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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