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

1#

What is the SI unit of momenj 1 82nudj* c5hbgwlkqm; 9t(ttum?

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, 40sak.zp na:aktr- ,vthe cannon 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 al)ogcmv:+f5 y iyk6xbb3r7 q,oong a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to t3 xq5y6,b b:r+gy )kicomv7 fohe 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 +6ca yhzu+l w5off a sled while sledding on frictionless ice. What happensc6+l 5w auh+yz to the velocity of the sled?

A. It increases.

B. It remains the same.

C. It decreases.

D. cannot be determined from the information given

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A rubber ball and a lump of putty have equal ma p9*kb 6rpvp1 ,oxtem1ss. They are thrown with equal speed against a wall. Thetp9erk6mv*bpp 1,ox 1 ball bounces back with 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. H xr29pf8;hrn k*m j-2i ii1htzo67j ebow would you represent its kinetic energy in terms of thesetm2-j1kx*ibhr ne8 ;pi29z 6hjif7 o r two quantities?

A. $p^2/2m$

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

C. $mp$

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

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you pitch a baseball with twice the ki-f7, agulj;x1my 6s finetic energy you gave it in the previous pitch, the mag il6y,a;- ugfxfmj7s1nitude 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 4igh4 gnqezz)7g) (idoj 0tfae8x z3u w4/uc6 in 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 conservattm pd zuy;n 1x/o)s5f)ion 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 timl d6akno 20ky3e (F vs. t) graph represents

A. impulse.

B. momentum.

C. work.

D. kinetic energy.

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Which of the following is an accurate statement+gnjs t1) 0 f)neov)0 iuwy4jx?

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 largev633ckw:mi .zp6ey zqa 8 /wnp truck in a head-on collision. Which of the following statements concerning the magnitude of the average collision force i:mv y3/ea wqnkpczz6pi8.w36s 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 r(f p.: q1zx 89wdlejland the other blue) are dropped from the same height, and rebound off the floor. The red ball rebounds to a higher position. Whi19e8 . w: pllxdrjzq(fch 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 m9 l:4lguz6 n f4y8ifga/s, collides with a stationary bowling ball. The4f469n 8i:zgu lf galy 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 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 bounc*s-(cw doys0g e off each other. Linear momentum

A. is definitely conserved.

B. is definitely not conserved.

C. is conserved only if the collision is elastic.

D. is conserved only if the environment is frictionless.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg object moves to the right at 4.0 m/s. It collplx9rji wq:9 t-c)0wss;1v akides head-on with a 6.0-kg object movi:jsk l1qawswit; 9 p v-90rcx)ng 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 2uelzwb c4l057 .0 m/s tackles head-on an 80-kg halfback rc ue7l5wzl40b 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 collisa+j qk,myh f sg)f80e;ion, if the momentum is conserved, then which of the following statements is true about kg8 mfh,e)fkq a;sj0+y inetic 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 energn6q jrbi k8-:dy 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 cue ball hits the #m*w ugj;e5x 7amw0n-qjh 3djxg.9a +s 5 ball and stops, while the #5 ball mohe+jaj mq sx9un* gj7;x3g0wa dm.w- 5ves away with the same velocity as the cue ball had originally. The type of collision is

A. elastic.

B. inelastic.

C. completely inelastic.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When a light beach ball rolling withnc/jbix kc,s ,./mg8y a speed of 6.0 m/s collides with a heavy exercise ball at rest, the beach ball's speed /m gyjbc.,xkn8 cs/i ,after the collision will be, approximately,

A. 0.

B. 3.0 m/s.

C. 6.0 m/s.

D. 12 m/s.

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22#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A golf ball traveling 3.0 m/s to the right collides in a head-on collision withed/ ekzc.t2:p a stationary bowling ball in a friction-free environment. If the collision is almost perfectly elasti ezkpct:/ 2.edc, 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*-3 uswwcuj .geisg 59 identical ball eugsj5w. *3s 9 g-wicuat 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 movi+bb6ib/iw(9 s q f)dhwng with speed v collides head-on with a very light object at rest. The collision is elastic, and there is no friction. The heavy object bar )+ bb/(hw6b 9sidqfiwely 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-ne3j j,m wy)yj;vssyx n.-j 6 v collides head-on with a very heavy object at rest, in a frictionless environment. The colli3jw;s mj-, 6xnvnesj)yj .y y-sion 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 velocity of +3.0 m/s c6b+ ulavzib7-q2 ko5 bdn6l)pollides head-on with a yellow ball of equal mass moviv apb-l6z)67udk b +nq2l5o bing 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 withue a0ldps7 h.3 velocity v collides head-on with a very light object moving with velocity -v. The collision is elastic, and there is no friction. The heavy object barely slows down. What is the speed of the light object after thepd .su0 lh73ea collision?

A. nearly v

B. nearly 2v

C. nearly 3v

D. nearly infinite

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

In an inelastic collision, if the momentum is conserved, then which oi3d+4 k /ql)w xwre5v.qfuv6hf the following stat/khf4)vu6di5ql+ wxvwr e 3.qements is true about kinetic energy?

A. Kinetic energy is also conserved.

B. Kinetic energy is gained.

C. Kinetic energy is lost.

D. none of the above

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects collide and stick together. Kinetic enermufn-28 e jb:2o1cezebd 3b4kgy

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 av 9 (x w0y w:kdec*lp+r52zwze perfectly inelastic collis5*(w+kyp:90ewezdw xcr2 l zvion 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 ob np6mxd( tqwxvw16p.4 ject experiences the larger magnid6xp( 4w6x nq.pwt1vmtude 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 ball and is deflected a5 jtb:jd5v xw4b:9qg xt 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 statemedp -od 5) hqjxw7rr, a16pvb)d;z2s6yo kg,ments is false?6 pa 7gd 2qy) 5wzv1e; rsxp,mh6j) odrd,o-bk

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 stateme jp2hl9l(u.x xnt?

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()mq9 zt beuw- 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/ m vmrqre1qtzov/1), , which explodes before hitting the ground. Neglece m/tvz,om1q rvq/ 1)rting air resistance, the center of mass of the bomb fragments, just after the explosion

A. is zero.

B. moves horizontally.

C. moves vertically.

D. moves along a parabolic path.

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37#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two cars collide head-on on a level friction-free road. The collauj feyoe5da84o s*-1auj,4 kision was completely inelastic and both cars quickly came to rest during the,j85kya 4feoj aes u1a4*o-ud collision. What is true about the velocity of this system's center of mass?

A. It was always zero.

B. It was never zero.

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

D. none of the above

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38#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State Newton's second law for a system of pavezwy --fy9 ,rrticles.

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 momentummgcq5e +u) sp. of a 2000-kg truck 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 ohj-nt8f gag75-vtyx8ph t, 0magnitude of its momengjy85 8n , htxgt 7fhpao-v0-ttum?

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 awj7 .wty7j /wt height of 12 m. Its momentum when it strikes the groww7jt.j7/tw y und 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 perpendiilcj z:/d1jt )cular to each other. One moves with a speed of 25 m/s due north and the other moves at 15 m/s due east. What is j/ tcjd zli:1)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 ho dvg*1dne d7i(rizontally at 30 m/s, strikes a wall and rebounds at 24 m/s. What(7dddeivn1 g * 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 asj 8a8.goz4l a speed of 12 m/s, is struck by a racket cauzaoajg s48l8 .sing it to rebound 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 tmg; kq+ -oi.uj2mk,r4uxdg* lhe baseball) is placed on a frozen pond. The machine fires a 0.40-kg baseball with a speed of 35 m/s in the horizontal direction. Whatud+mrl;mq. -u,kg4k j x*g2io 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 capsulemt9mf4q k, qx.0woq*t j.twmbj3w.r* and is stationary when the tethew 4 ,f 3 jmqkt*mb.o.q0tmqw*9jrtwx.r 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 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 objec9;-h1xd t7knwxqb -ile8rx.d t at rest. The smalddhtwkn 9 i;8-7x xer.-blq1xl object bounces straight back with a momentum of magnitude 4.0 kgm/s. What is the magnitude of the large object's momentum change?

A. 9.0 kgm/s

B. 5.0 kgm/s

C. 4.0 kgm/s

D. 1.0 kgm/s

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You (50-kg mass) skate on ice at 4.0 m/s twa*sk tp9 f0j9 i)mj9uo greet your friend (40-kg mass), who is standing still, with open arms. Asj9skp i0w)9jfu 9*mat you collide, while holding each other, with what speed do you both move off together?

A. zero

B. 2.2 m/s

C. 5.0 m/s

D. 23 m/s

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of mass 1000 kg moves to the right along5nhl plvjj37f ,r k ve8o4(n6g a level, straight road at a speed of 6.0 m/s. It collidef rn,4(ej8vo v nh lklgj5p637s 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 mbp+v-nl 2f6ru/s runs into the rear of a stopped car that has a mass of 1500 kg and they stick together. What is the speed of the cars after the cfb2v- u+6lrp nollision?

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 kg, is a-s92vozq3ub gllowed to coast along a level track at a speed of 2.0 m/s. It collides and couples with a 50,00bs3z qo 9v2-gu0-kg second car, initially at rest and with brakes released. What is the speed of the two cars after coupling?

A. 0.46 m/s

B. 0.60 m/s

C. 1.2 m/s

D. 1.8 m/s

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A railroad car, of mass 200 kg, rolls with negligible friction on oq vi(me 4i8lq3f mp 1bo.c7/oa horizontal track with a speed of 10 m/s. A 70-kg stunt man drops straight down a distance of 4.0 m, and lands in the car. How fast will the3o8pvmo/7e cqi 14lfiqm .b(o 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 loc3v ay :v.imh4uw3bc 2g at the rate of 0.80 m/s (with respect to the log). With what sv2vcchu wi4.ab 3:3ympeed 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 to3lk m x3o9tp*y 15 N and acts for one more second. Whatopyt 39l3km* x 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. Whatn ) 8sjg:f ls 8/s0ol;zwywsyv)h8s3p is the object's changew3swh8fys s)jgsn8 y/: 8 lvpzo)s0 ;l of velocity?

A. 3.0 m/s

B. 9.0 m/s

C. 27 m/s

D. 110 m/s

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2000-kg car, traveling to the right at 30 m/s(p 5aebr)uie 1, collides with a brick wall and comes to rest in 0.20 s. What is the i1 b)up(5 eaeraverage force the car exerts on the wall?

A. 12,000 N to the right

B. 300,000 N to the right

C. 60,000 N to the right

D. none of the above

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg softball is pitched to you at 20 m/s. Yoxs, zqh9wu3ak,l5ek g gt4y,+u hit the ball back along the same pathht k 5gw,+gy z9,a3qu,kxsl4 e, 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 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 the80ysr2cu q(mdt56cytio xr)r z64 .je 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 the ball)rd5rjz mu2 8sc46(6 .eroqtx t i0cyy 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. z(2 + eudd4(,jjit.pm lroib*0 kg, fires 50.0-gram bullets, with a muzzle velocity of 750 ojld,4* jdzr.itmbui(ep+2( m/s, at the rate of 300 rounds per minute. What is the average force exerted on the machine gun mount?

A. $94.0 \; N$

B. $188 \; N$

C. $219 \; N$

D. $438 \; N$

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A fire hose is turned on the door of a burk2r7(ju izpk +ning building in order to knock the door down. This requires a force of 1000 N. If the hose delivers 40 kg per second, what is the minimum velocity of the stream needed, assuming the watu 7krji+kp2 z(er 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 minub.1dn5sk4nu0fc lrz ( te. It falls 3.20 m to the ground. Assumin 10bnnu(4zkf l.ds5rc g 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 aftj6)dyyl x kc41o1r:dxer 3.0 s, when fired straight up. What average thrust force does the rocket elj46y1kd)d xo1y :xc rngine 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 outer spaced tj* wsd/i7 easp:t2:. They push each other apart. What is their separation after the lighter astronaut has mov/ :i2ae: 7j*pdss wtdted 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 withmu;vmw79vhy- pi: b f7 a speed of 2.0 m/s. It collides in a perfectly elastic collision with a 6.0-kg object moving to the left at 1.0 m/s. What is the total kinetic energy after the colli9pi:mw;-f 7v7vm yb uhsion?

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 ma4 wx:pql25 puskes 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 :qxw52pul4s p 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-l- uh5s9 j3ah*fje6vbkg block at rest. The bullet emerges (the bullet does not get embedded in the block) with half of its original speed. What is the vela6vh 9-j3luj5e*h bfsocity 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, ieyg 76rtpm7.s0dbx. 8 juyxys.ef6 a(s struck head-on by an alpha-particle (which consists of 2 protons and 2 neutrons) moving at speed v. If the collision is completely elastic, what speed will the alpha-particlexj6x0 .8.yesp r7sgmt .yb(ud6yf a7e have after the collision? (Assume the neutron's mass equals the proton's mass.)

A. zero

B. 2v/3

C. 3v/5

D. 5v/3

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-gram ball moving +10 m/s collides head-on with a stationary ball of ;a;0xnif5xct unf u;i(l2 k.ymass 100 g. The collision is elastik;intc x ufa(n 52i.0;x ;yulfc. What is the speed of each ball immediately after the collision?

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

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

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

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

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69#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

A ball of mass 400 g moviv+vl + z)4zn(yau y(axng toward the east with a speed of 3.70 m/s collides head-on with a 200 g ball sitting at rest. The collision is perfectlyy va +xn(+z4vauz)l y( 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.ri)5s6mzl+f k :zs5z12pti pd 0 m/s. It collides head-on with a 3.0 kg mass at rest. If the collision is perfectly inelastic, what is the z6 f 2rt5:) zmpisik+5zds1plspeed of the masses after the collision?

A. 10 m/s

B. 2.5 m/s

C. 2.0 m/s

D. 0, since the collision is inelastic

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass moving to the east at a speed of 4.0 m/s collides head-ow3+7wdw- 4k(5a btypstawiw 1 swp5( nn in a perfectl4ab+t7wi5 pswsyn w kdw1p5(3(wa-tw y inelastic collision with a stationary 2.0-kg mass. How much kinetic energy is lost during this collision?

A. $16 \; J$

B. $4.0 \; J$

C. $8.0 \; J$

D. zero

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A car of mass m, traveling with a velocity v, strikes a parked station b8dfg/jyb -2jl3ft 0r u4ua4awagon, who's 8bju-3 a04u/ rft blgad4fyj2 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?

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 inat/etmqh+ho0:kr)d) ,k 6sw f a vertical direction buries itself in a 2.4-kg block of wood a rest directly above it. As a resultta)dh:rk6 0)mwhsoek+ ,f q/t, 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 coi dcjc293+ etjj+ 5w)ek8rqr7dd 0pf fllides 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 thqp5 ir dc7+c+tk j0fdf9e8wr) e2j3jde 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 co9 hqeub ry-cc7tg*6u8llides 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 direction of motion of the cars afterhbrte qug7y *8 cc69-u 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 surface. Objecr8dmkg8p9+s adb ia(i7hr q28t A moves east with a momentum of 24 kgm/s. Object B moves north with momentum 10 kgm/s. They make a perfectly inelastic collision. What is the magnitude of their combined momentum i bs8a8ra gim9dk8 +(p 7q2rdhafter 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 76noo8 pkf4 hpbvc+,nmoving 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 fragment movinhpno6v b+4 8kp7cn,ofg 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 (.db7p nl 8llwm m/tlqj59 kmr 3ktn *(k,w0ux10.0-kg mass sits at x = + 21.0 m. Where is the center of mass on l( 035rwn,7d9k (tl8mj*bt mkllxm.wup/qkn 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 ag koa*0d*zr vz 4,u 8oy8lg-ab two-particle system is at the origin. One particle is located at (3.0 m, 0) and has a mass av-48, 0ozzg8 dury**a kgoblof 2.0 kg. 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. ::/hatnyb4 kh0, 0), and 4.0 kg at (2.0, 1.0). Determine hkhb/ :naty4: 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 ld)5 j qnvej-.aq xog9-ocated 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 of jje -dna-9x qqo g)5.vthe 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 mass is positioned at,+up i m9sj;lqw-c0l j7py8 gk (12, j7w pu90i+sq;,cgk8-pmlljy 0). What are the coordinates of a 4.0-kg mass which will result in the center of mass of the system of three masses being located at the origin, (0, 0)?

A. (-3.0, -6.0)

B. (-12, -8.0)

C. (3.0, 6.0)

D. (-6.0, -3.0)

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Use Table 7-1 to calculate the position of the CM of a whojg8ugz9o 6d r2le leg including the foot when theo gud2rj869 zg 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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