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

1#

What is the SI unit of momentue(gcgru. 4bmd .2s;uim?

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 recoiln;vt9,z bilb / 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 railroad track at conn.1jj (u nir4vstant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happennn(.ji41 jvur s 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. Wicw:t5(q u8 u.kh e(xchat happens to the velocity of the sledqkh(. c: 8uwcu (te5ix?

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 thrown with equal s78s zca*ye7u:p w u 8ihl(:c+joz-xujpeed against a wall. The ball bounces back with ne+8lej:7yo (cz h:j7c-z8a piuxwsu*uarly 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 wz. b hf(8k.hzdith a momentum p. How would you represent its kinet.fzdhz8 ( .bhkic energy in 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 twic ssgpscjh6w,t 4amm- 1i0dtn*( e8w dscj5/g6e the kinetic energy you gave it in the previous pitch, the magn5mcss( ,sed wjsi0cw8 nj ap*tg-h/m4dg 6t6 1itude of its momentum is

A. the same.

B. 1.41 times as much.

C. doubled.

D. 4 times as much.

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8#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State Newton's second law ienxjy8 *pw 5-yn 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 conservat brq *uy5lpuccv(; nzcwe0 2kk nc7378ion 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) graptwiv7ulodq: q9t+(zm ;, r2to(xyy 4 vy8( plzh 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 emletxdw cr u:9htq:(u/,wt. e(g2 +van accurate 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 w t*utq,pamkw1y oneg2+4k* 3ooi:k e- ith a large truck in a head-on collision. Which of the following st o+u3pny:- gq2 w *me1*kkt4t,eo aikoatements 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 the other blue) aree 58 xyi/9y.zt ho l3g10gnciw dropped from the same height, and rebound off the floor. The red ball rebounds to a higher position. Which ball is subjected to the greater magnitude of impulse during it35cez/oty .109xyn ghlii8 gws 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 stue,l.inn /44/),to hqomjzi aationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse durielnn,i,ojh44oi/.uqm/z a t)ng 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 ezalfmq/e1 x-; 7 ht1ynach 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. y3/l(v98e,v ahn pu r6s2osvs It collides head-on with a 6.0-kg object moving to the left at 2.0 m/s. e82rovvy93n a( v us6sh,spl/ 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 dc,+f4 wkof:j/s tackles head-on an 80-kg halfback rfw:k +,df4coj unning
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, thenk.7b:6 9jq:e v;eqo alk0co/d/npnxu which of the following s/:c oop9v;nn/6 ek:0 u .j7 lxqbkqaedtatements 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 energyzme6q z-:x 9tf conserved?

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 cw sx44c-l ewf12w-vckue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue baw4kfv -cel w4-wcs 1x2ll 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*n k)7d0j*dn k ,i :zv.k0hxm73w i .tztexdjk.0 m/s collides with a heavy exercise ball at rest, the beach ball's speed af wt dxkz, dmj 0nj3kin7ixvt7:).*ze0.kd h*kter 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/s to th-c grq- b1j+ore right collides in a head-on collision with a stationary bowlio-j q+r-gb rc1ng 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 head-on elastically with an iden8.:(bxrhtmpsrl d 9-ttical ball at rest. What is the speed of the initir ls.: 9xb-rh(m8dtptally 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 l7zlbzq(.a)t ;oxayz; e l/u1 dight object at rest. The collision is elastic, and there is no friction. The heavy object barely slows down. What is .;d1azzte7u)y( l; x/qoazblthe 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 wvc2vl: kym eon/0 m2r,ith a very heavy object at rest, in a frictionless environment. The col my nv/v22 e:0om,lcrklision 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 veloc q6r1kcsccry oz 9w x2-33h-qmity of +3.0 m/s collides head-on with a yellow ball of equal mass moving with a velocity of -2.0 m/s. What is the velocity of the yellqq1wr- cy293occx s- mz3r6khow 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 w: da45m6tt+(4tix-iz s 23mk vw varycith 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 4 264z5cwxtd ivivtt- asm(:y3r k+amafter 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, 2ryc 3 lr)e-vbthen which of the following statements iserly)b3- 2 cvr 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 togejgr9f v)xkenz -6/3 w-,wim iqther. 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 in *,*a9do*huoxba gkg 9elastic gh9gaokxo*,*u *abd9 collision 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 stx2 a9 a-ov7fu bse pat7n4+y6eicks. Which object experiences the larger magnitude of moment4a 7tfea9e xya2p +76 -nsvobuum 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 g,r bhn/l-hktfi +z(fe/ 4,be#9 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 mastybgf laf/p/ 40yndp:7/4a f rses, M and m. Which of the following statements is false?7 lff0/ a/patdp/nbyr f:4 g4y

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 xpqxtf6p;c:i-j (6fl l lo4x7is a false statement?

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

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

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

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

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Tightrope walkers walk with a long flexible rod ,9;ewrfp if g(8a fe j;na (6ap*)usxiin 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 horizazhlq xwles 7n-/ f.-:5mzg q7ontally, releases a bomb, which explodes before hitting the ground. Neglecting air resistance, the centshl5/ l-. fzqz- gqa:x7nwme7er 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 rwlfnv5+l3 :4f+jp+mxau* ggwm86+ jxarbmz :oad. The collision was completely inelastic and both cars quickly came to rest during the collision. What is true about the velocr:6u wf+xm 4*g +xwfzmng3mjaal jp+:b5 v8+lity 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 sysz0g*dn ge6:z+gml)tc qlo7 f0vy:,a lj3e (votem 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 travet 0y57e r:gqfzling 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 mswowp g 256s9aqk madp-h )e41/s. What is the magnitude of its momentumd4 9w5hq pe)m-2wkoga 1s sa6p?

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 . xra -b/yu.q(:/xhd.wy yaizit strikes xr:(h ybuw.-qyd a.iz//ya.xthe 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 eyt/dbi) 7ek:mude*c:a) kt h ,ach other. One moves with a speed of 25 m/s due north and the other moves at 15 m/s due eas:u :7a/b ,hc mdk) etdtyiek)*t. 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, strikes a wall a;ah/ /f2rh bfund rebounds at 24 m/s. ;hfah/rbu2f / 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 atj70n d-9 lkshb a speed of 12 m/s, is struck by a racket causing it to rebound in the opposite direction at a speed of 18 m/s. dl0nb s9hk7j-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 placed on a frozen pozw-(etn5 jzuw4 q5( n3-s-o)fxqdup qbh7ow;nd. The machine fires a 0.40-kg baseball with a speed of 35 m/s in the horizontal diruq;j q-b dzw)-4esp wz3uxq7-n ow (f5t o5(nhection. 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 sp/ka9etn- tg; lace capsule and is stationary when the tether line breaks. As a means of returning to the capsule he throws his 2.0-kg9kt/ ;-gtenl a 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 apprgm .rbspgg-;3e/ wv 3ula)iw6oaches head-on a large object at rest. The small object bounces straight back with a momentum of magnitude 4.0 kgm/s. What is the magnitude of the large object's momeng3seg .lv;bg-ra6 p 3i) mwu/wtum 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 +x;hniho). zi greet your friend (40-kg mass), who is standing still, with open arms. As you collide, while holding each other, ino)hx+ i;zh .with what speed do you both move off together?

A. zero

B. 2.2 m/s

C. 5.0 m/s

D. 23 m/s

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of mass 1000 kg moves to the righz j8l/b9qfpro w;6z ;; a0fwfet along a level, straight road at a speed of w; 9wz jr 8qlabe/ f;0op;ff6z6.0 m/s. It collides directly 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 thatr783ct0gyz 7wk(dybah 1y8sp has a mass of 1500 kg and they stick together. What is the speed of the cars after the coybr37 t1 7spzw80g (y d8cykahllision?

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, :.lm37pjk1:dxe9 wck db, bmdmass 15,000 kg, is allowed to coast along a level track at a speed of 2.0 m/s. It collides and couples with a 50,000-kg second car, initially at rest anb,3k.pd1m 7c wxkj ldb:m9e:dd 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 negligible frictbu df,f-uqy ;7ion on a horizontal track with a speed of 10 m/s. A 70-kg stunt man drops str-7b,yq;f udf uaight 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 of 0.80 m/s (withi(,jhk-fg5 1.f kmwm) rzupvhz m x5*: respect to the log). With what speed does the log move, with respect to jw .mh z(gzifk*5 phum:r vmf)kx15 -,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 suddpx ) mh9pp a*qxcrnzf,)-/h5x enly increases to 15 N and acts for one mor/chmhx) 5 apxqp) p-rf9zn,*xe 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. b *koz57vlp.(p o ict- What is the object'(ozip . o bktlcvp7-5*s change 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 tod66 4j vxhgt8he 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 thd xt6jhg4 8vo6e 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 the balmw 9btbqby6n5kgkjldg 8 6.5 .l 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 thebjqy..5 gk nb6dt6 m598gkwbl 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*7 g5cwh lwc)paou2u1vx9o9wer ,l6n ur:1 s b 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 th7u2er1:s)w *p1c5gnlo ucrvu,9awxl 9 b6 woop 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 veloa7su fho;i2i/dq d,6dcity of 750 m/s, at the rate of 300 rounds per minute. What is the average forc f 2adu7 s,d6oh/;iiqde 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 di h :u.f4kaadzi 14uv*-p,qthqaa6m 7oor of a burning building in order to knock the door down. This requires a force of 1000 N. If the hose deliverstif-aa74 p 1 hv hqiuz4k 6aq:m*ua,d. 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 rapb :b0gzt e6r/o tvu*2te of 120 kg per minute. It falls 3.20 m to the ground. Assuming the water doesn't splash up, what average force does it exert o6re* : t2u0b/obzpgtvn 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 k3 59piyme4xvi(-gysz g, achieves a velocity of 40 m/s after 3.0 s, when fired stravsi 4pg(95y y-xiz3m eight up. What average thrust force does the rocket engine exert?

A. $1.2 \; N$

B. $1.6 \; N$

C. $2.8 \; N$

D. $4.4 \; N$

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two astronauts, of masses 602 j fipv8ykx 4w4qgi*0 kg and 80 kg, are initially at rest in outer space. They push each other apart. What is their separa24 jgvi8* wqfpk iy0x4tion 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 wzz: 7(q a pj9 3wi,lwnlnds-t;ith a speed of 2.0 m/s. It collides in a perfectly elasticdz,nzil: n;j 3(7tpw-q9lswa collision with a 6.0-kg object moving 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 velocq.n1+8 ysihiu. 6szle 2 .ad1f p twgzdws.4v;ity of 0.20 m/s in the +x direction makes a head-on elastic collision with aw4d g i. ap+8wd .z tuzsv6;qse.ylsh.nf21i1 0.15 kg object initially at rest. What is the final velocity of the 0.10-kg object after collision?

A. -0.16 m/s

B. +0.16 m/s

C. -0.040 m/s

D. +0.040 m/s

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. l3ya.5ukfga )ou 0qv3v6zdr .The bulled zaa6g kuoul0r .f5) vq3yv3.t emerges (the bullet does not get embedded in the block) with half of its original speed. What is the velocity of the block right after the collision?

A. 1.50 m/s

B. 2.97 m/s

C. 3.00 m/s

D. 273 m/s

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A proton, of mass m, at rest, is struck heaki6d/.w)hi bbd-on by an alpha-particle (which consists of 2 protons di6b/.)bkhw iand 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'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 statkc jptf.( r9i(2 a,(mj3ug wrzionary ball of mass 100 g. The collision is elastic. What is th.3g2r ,wuk( cm9r(ftj pjzia( e 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 ag,xa 7fs26yxeast with a speed of 3.70 m/s collides head-on with a 200 g ballg627y ,axafsx sitting at rest. 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-on with xbczbzh qjbfs9i i/o.ytq/lz9x(f+5j;(+s.a 3.0 kg mass at rest. If the collision is perfectly inelastic, what is the speed of the masse+i(j;+lsq.(z /zq / ybbx.fci zsj599 bxhfot s 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/dy36 (1skzznsay 29bg s collides head-on in a perfectly iy12da9ybg(zkz s3 sn6nelastic collision with a stationary 2.0-kg mass. How much kinetic energy is lost during this collision?

A. $16 \; J$

B. $4.0 \; J$

C. $8.0 \; J$

D. zero

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of mass m, travet8c08s,ru zmlling with a velocity v, strikes a parked station wagon, who's mass is 2m. The bumpers lock together in this head-on inelasticm l08urt zc,s8 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 direa:2yw 7en k p2rc8801 +mrmy dmdkvjf1ction buries itself in a 2.4-kg block of wood a rest directly above it. As a result, the bullet/blocey8c m myvam22d7r0j8k:dk1 n+p 1wfrk 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 905l s8til(to or7t) cgu+l,* 5mzmwzq7.0 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 afte(+uom5zgt iz7ll 7 5rc)tw8tq ml*s,or 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 c an;7s3.z*pq5r n4 yu axq/ewuollides 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 ts/uq xe4n r*5wq37yan.au ;zphe 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 frictionless surface. Object A moves e(cy pb 0 ak3rplm7*)sa4+ krzvast with a momentum of 24 kgm/ azyc0k37 r*klmrs p4)pv (+abs. Object B moves north with momentum 10 kgm/s. They make a perfectly inelastic collision. What is the magnitude of their combined momentum after the 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 North with a velocity of 4.0y gse5x, /k 0pxf2dc7u 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 sye0,2x/ k5dg cu7 xfpmoving east with a speed of 10 m/s; and a third fragment with a mass of 1.0 kg. What is the velocity of the third fragment? (Neglect air friction.)

A. zero

B. 40 m/s north

C. 40 m/s south

D. none of the above

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78#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg mass sits at the origin, and a 10.0-kg mass sits at x = + -.m2adno)q sv a0p +kojg yg xl(53,cf21.0 m. Where is the center of mass on the x-axis?+.o y lf g3v,qs(gxmo0 c) ap5dja2-nk

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-par rrj 3oil*4/p3g lnuup5 mt::rticle system is at the origin. One particle is located at (3.0 m, 0) and has a mass of 2.0 kg i3 3plrm lngor:trj*5u:/4up. 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, 0), 2.0 kg at (2.0, 0),a rx 3k/hps).w and 4.0 kg at (2.0, 1.0). r. axhpk/3) swDetermine 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 kg, are located at (g4v-t,qe6w*ubji5 zp bmff2- 0, 0), (1.0 m, 1.0 m), and (2.0 m, -2.0 m)iv, 5jugb*f24pqbf z6-mte-w , respectively. What is the location of the center of mass of the system?

A. (1.3 m, 0.67 m)

B. (1.3 m, -0.67 m)

C. (-1.3 m, 0.67 m)

D. (-1.3 m, -0.67 m)

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg mass is posii)fj)fc trbu /dy3g*g:j+a, utioned at (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 the center of mass)g 3d/tufia*y+c:g)f urj jb, 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 2zg/v : oy cwtp+ka3(mh0w cd*CM of a whole leg including the foot when the leg is stret0 yc2 z (hwop/:g*k3+mcdtw avched 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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