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

1#

What is the SI unit of momentum?;y7dp : cf6jkgu*udvbxi-* p5

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 reca/w yrq -nb;y84pi l:eoil 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 constant s)444 b kdaunuepeed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the vel4n)4bea uk 4udocity 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 ovfik6d yta;x5ajs2 * 7n frictionless ice. What happens to the velocity oayjt xf sikvad7*5 2;6f 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 sy72xke/zmqd:cu; 3l ( r1ppbof putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the s;sdpp my1k /: z27cer(3 lxqbuame 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 wiz9 ;g ie7shugz :fd))rth a momentum p. How would you represent its kinetic energy in terms of thessr;gh7:fdg i zuz) e9)e 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 kinetic energy you ga7 wag 9)q5ujsfve it in the previous pitch, the magnitude of its momentum 5jw)9 aqsfu7g 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,d8xt61eggmkzk w/ 3f terms of momentum.

该题自我估分: (必填) (满分:1.0分)

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9#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation of momencj.2 dn y-4ivrtum.

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 ojgsf 6nj9t46vs. 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 statemej 9 fydjnf;th,e;9; tcnt?

A. The momentum of a projectile is constant.

B. The momentum of a moving object is constant.

C. If an object is acted on by a non-zero net external force, its momentum will not remain constant.

D. If the kinetic energy of an object is doubled, its momentum will also double.

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A small car meshes with a large truck in a head-on colls s8c7cq1 6nueision. Which of the following statements concerning the magnitude of the average collisioq8nc csse176un 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) are dropped fro p 9w5g4gogxmi. r),dfm the same height, and rebound off the floor. The red ball rebounds to a higher position. Which ball is subj9pf od xg.m)rg g5iw4,ected to the greater magnitude of impulse during its collision with the floor?

A. It's impossible to tell since the time intervals and forces are unknown.

B. Both balls were subjected to the same magnitude impulse.

C. the blue ball

D. the red ball

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A Ping-Pong ball moving east at a speed of 4 m/s, collides with a stationary l/*,htisn;bsmj t* -xy g5i+lbowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object expem*y+t,ns 5s h/-x ljbiitlg;*riences the greater magnitude impulse during the collision?

A. Neither; both experienced the same magnitude impulse.

B. the Ping-Pong ball

C. the bowling ball

D. It's impossible to tell since the velocities after the collision are unknown.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects collide and bounce off each other. Linear6rtl6:c- pa ve jlu4k3 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 coll//-s: ftv-bsdy5n nahav co0+1 .nnjpides head-on with a 6.0-kg object moving to the left at 2.0 m/s. Which sp n.ya0das ofbj1hnnt5vs -/+:- /n vctatement 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 movixt-n7l gy1c4vng at 2.0 m/s tackles head-on an 80-kg halfback runni7cvly41 g -txnng
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 5g )f(pai5y djiol2w1 conserved, then which of the following statements is true about ki(j55iy p)fw iglod2a1 netic 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 gur/ad(l*s gyhb e ,/pg1a7(a 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 hivuma98:0iae84w4p a6kw xif qts the #5 ball and stops, while the #5 ball moves away with the same veaa 840pmiv:i f6waeu 4x89k wqlocity 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 with a speed of 6.0 m/s collides with a heav; (jguvozv n skmjd5;vk q;),+y exercise ball at rest, the beach ball's speed auv; ;5(qzkokjj;ns+vmg ,)v d fter 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 tyzhay3gth+t a,z) .b4o the right collides in a head-on collision with a stationary bowling ball in a frictiohay.,t zh) 4gtb3zay +n-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 coy( 60w f*g pgda ::+so(hm :sjs6zhsxmxt*sl-llides head-on elastically with an identical ball at rest. Whoxy:f h+:6ssz 0ms*a dg6hg-s *(wsj pltmx(:at is the speed of the initially stopped ball after the collision?

A. zero

B. 1.0 m/s

C. 2.5 m/s

D. 5.0 m/s

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very heavy object moving with speed v collides head-on with a very light objemh qxqe7a:dvf/1o0*ioh, qi m+ dnl **tyw8z:ct at rest. The collision is elastic, and there is no friction. The heavy object barely slows down. Whatht7yn*h1z*wd0m+ xo:fq,iq8 qmae oi/l: v d* 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 heavyh-y wzev1)/ws object at rest, in a frictionless environment. The collis/-h) evwysw 1zion 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 collides head-3s6u96wfryc5fzv ax *i +m n.iy6m a/son with a yellow ball of equal mass moving with a velocity of -2.0 m/s. What is the velocity of the yellow ball after t/5 a6aw rcs.6* yn+3 ixm9v6sfzfi uymhe collision?

A. zero

B. +3.0 m/s

C. -2.0 m/s

D. +5.0 m/s

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very heavy object moving with velocity v collides hea u.,tmbz3 csr w3u:v2jd-on with a very light object moving wit,.jvc 3wzb: r2mtusu 3h 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 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 momentud/r +ollbm wjqc+196jm is conserved, then which of the following statements is true about kinetlq9jd rc6bljmw/ ++1 oic 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.b5nvvbfqy 7ilz6q p:g088idj,oj) 89bg4b x g 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 toh* hj,z6. u;or3q3oj wiau 3nn the right at 4.0 m/s. It collides in a perfectly inelastic collisionj,3i6u azowh3q*n;noh 3r uj. 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 stic qdtau/b ce+ x)1 po5zsu-8t1xks. Which object experiences the larger magnitude ofz/+u1ptuedaxo5 -c1 8 bxsq)t 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 balll ko)7xm;seu( hits the #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 masses, M and m. Which of the following stao.orejq*ybp c7,q6nb6-g nv 9 tements is falso6rgy* pb,j 6 .9ncoebnqv7q- e?

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 statementu ao9gfi(eqwn 0d/r1.tpcj 6 :?

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 ctuyrz /64ul5a long flexible rod in order to

A. increase their total weight.

B. allow both hands to hold onto something.

C. lower their center of mass.

D. move faster along the rope.

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A plane, flying horizontally, releases a be4 6t l(iitixt+h3ck)vv m,.komb, which explodes before hitting the ground. Neglecting air resistance,xk(i m6,i vikl3h.+) tctte v4 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 roh4oxths0is-2h (ua:e ad. The collision was completely inelastic and both so4h(- 2 x uhtesa:i0hcars quickly came 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 for a system of kr*9rdsbgx0*-(vhw b 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 traveling atxpc 8lebs;4 n2 flhd+8)h .lqqnc4hg* 35 m/s?

A. $57 \; kg \cdot m/s$

B. $3.5 \times 10^{4} \; kg \cdot m/s$

C. $7.0 \times 10^{4} \; kg \cdot m/s$

D. $7.0 \times 10^{5} \; kg \cdot m/s$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1200-kg ferryboat is moving south at 20 m/s. What is the magnitude o f74p8 tn*j-xa*z9*21j dranfxv*xk3cx tso hf its momdxtr-j83*of a*h j*fs*nxk74a1x v92ptn zxcentum?

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 1cc8rek,5( rps 2 m. Its momentum when it strikes the gr rr( ek,cp8cs5ound is

A. 1.5 kgm/s.

B. 1.8 kgm/s.

C. 2.4 kgm/s.

D. 4.8 kgm/s.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two identical 1500-kg cars are moving perpendicular to each other. Ont6l,xu ljyqez 6qw w-*+9d( nwe moves with a speed of 25 m/s due north and the other moves at 15 m/s due east. What is the total momentum of the systemdx-ww6tl u6(q,+z e*q y9lnjw ?

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 qv dyl7b02/.y6m: f+ce q d5zoo)hweu wall and reboundsh5de /b0yo6yzu:2 e cqmdo.7flwq)v+ at 24 m/s. What is the change in the momentum of the ball?

A. 0.60 kgm/s

B. 1.2 kgm/s

C. 5.4 kgm/s

D. 72 kgm/s

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.060-kg tennis ball, initially moving at a su ccng*zps+ha1*;k3 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. What is the change in khans*ugc1 ;* 3z+cs pmomentum 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 machict 9/7:sqvlulkde )o 8ne (excluding the 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. What is the recoil speed of the pitchinve/ dtoqsu:k) l7cl8 9g 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 statis/(7 qxn3iaz:s9thcbi d k7b4 onary when the tether line breaks. As a means of returning to the capsule he throws his 2.0-kg space hammer at a speed of 14 m/s away from the capsule. At what79k47qci ( / bs:bnixzht3sd a 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 approaches3b dg-y0qao8mx9f2,dtt zvd, head-on a large object at rest. The small object bounces straight back with a momentum of magnitude 4.0 kgm/s. Whd 38 2m,fvo bdyzt q-,9agdx0tat 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-kg mass)6w6( yf0sdbtu3m k n4n, who is standing still, with open arms. As you collide, while holding each ot6(6s ndbytk3 m0 4uwfnher, 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 along a level, straight road at a speedm +9otn n39ddycz0x5 b of 6.0 m/s. It collides directly with a stopped motorcycle of mass 200 kg. What is the total momentum after thet0c ny 3od9+dmx9 nbz5 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 runsz9/) bxfop lwt,rd k0; 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 ,/k9)dwbz ;tx folp0rcollision?

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 all4l9)eau bsx1 csdh1y0owed to coast along a level track at a speed of 2.0 m/s. It collides and couples with a 50,000-kg second car, initially at rest and with40)9 a lsse1x1 bucdyh 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, 1(w n(* e4rj wjh)pksqrolls with negligible friction on a horizontal track with a speed of 10 m/s. A 70-kg stunt man drops straight down a distance of 4.0 m, and lands in the car. How fa ( jn(s*kqpwj1 e)rw4hst 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/q ddk5g lc u:t8tu6+:/lu/n lco,air3s (with respect to the log). With what a:c:nd+8qko utt ,l/3 uculrgl/6 id5speed does the log move, with respect to the shore?

A. 0.24 m/s

B. 0.30 m/s

C. 0.48 m/s

D. 0.60 m/s

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-N force acts for 3.0 s on an object. The force suddenly increases to 15 8ip/-u7t+ p 6 wuappheN and acts for one mp/e+pa-u ht876pi w puore 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 on9quoy8 4euz20 njan qa,m-. di a 6.0-kg object. What is the object's change of veloc2q94n0eajy8a umiz d,n. o-qu ity?

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 rig gns0f)y 8uc:; 5k yfmbq6o-vhht 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 s)yfbc6m :k5n h;qof 0gyv8u -on the wall?

A. 12,000 N to the right

B. 300,000 N to the right

C. 60,000 N to the right

D. none of the above

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg softball is pitched to you at 20 m/s. You hit the ball back along th-9wv16 qxyt zj 06ouim+atj 5ee same path, and at the same speed. If the bqoxz 6t ey+u5j6a m1v0j-iwt 9at 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 r6.n4)m uqk2a/l-feq8o tssu table 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 tfsn)2s.o-4kqr8a ue l6mu /qthe table top lasts 0.15 s, what is the magnitude of the average force exerted on the ball by the table top?

A. $0.67 \; N$

B. $1.3 \; N$

C. $3.0 \; N$

D. $6.0 \; N$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A machine gun, of mass 35.0 kg, fires 50.0-gram bnt+(*gx )yj( esomx (cnc9s/g4 )qwrm ullets, with a muzzle velocity of 750 m/s, at the rate of 300 roundst y*ss+wexm xng(g) r4cmoqj(c/( )9n 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 burning bu,;z 7aycbo ro,ilding in order to knock the door down. This requires a force of 1000 N. If the hose deliverz;,oyacr , o7bs 40 kg per second, what is the minimum velocity of the stream needed, assuming the water doesn't bounce back?

A. 15 m/s

B. 20 m/s

C. 25 m/s

D. 30 m/s

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Water runs out of a horizontal drainpipe at the rate of 120 kg per min8ls5k bh+x dsr(ay6d1ute. It falls 3.20 m to the ground. Assuming the water doesn't splash up, what aved(8ssl1bx k +a5hyd r6rage 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 al(6 uh)5g 6chhhdqd9mw *d9 vof 40 m/s after 3.0 s, when fired straight up. What average thrust force does qd*9 hwm66vgh )addhhl5uc(9 the rocket engine exert?

A. $1.2 \; N$

B. $1.6 \; N$

C. $2.8 \; N$

D. $4.4 \; N$

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two astronauts, of masses 60 kg and 80 kg, are initially aa tmxru-cizds6,kq37ge b0-,/ svs(rt rest in outer space. They push each other apart. What is their sepax0t u6s,(s zcq kv7rmg3sbi /d, ra--eration 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 rightej sxbq,+er : t4cs;o/ with a speed of 2.0 m/s. It collides in a perfectly j+rs; :qs,e 4c tex/obelastic 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 velocity of 0.20 m/s ins.df gtd.4w 6xd au1o7,ba 3*ywal;em the +x direction makes a head-on elastic collision with a 0.15 kg object initially at rest. What is the final velocity of the 0.10-kg object after collisoud*a aw;7,dewa. xdsy1t6lm4 b g3.fion?

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 )qwa4 ociu;vh8fo;1z fired into a 1.00-kg block at rest. The bullet emerges (the bullet does not get embedded in the block) with half of its o fc )w;uooa8 1zi4;qvhriginal speed. What is the velocity of the block right after the collision?

A. 1.50 m/s

B. 2.97 m/s

C. 3.00 m/s

D. 273 m/s

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A proton, of mass m, at rest, is struck head-on by an alpha-particle (which conu 8z-2 zrgs+itsists of 2 protons and 2 neutrons) moving at speed v. If the collision is completely elastic, what speed will the alpha- g +rtiszu8-z2particle 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,cuj0b-/n 2*rnzf skv head-on with a stationary ball of mass 100 g. The collision is elastic. What /r0nb *czu-s,jfn2vk is the speed of each ball immediately after the collision?

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

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

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

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

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69#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

A ball of mass 400 g moving e **i f*:oyae3h qs;0jqk6igf toward the east with a speed of 3.70 m/s collides head-onyaeh0 if6*siogfqk3** e j: q; with a 200 g ball 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?

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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 spetfk3e5vxe9wl -egw5 .ed of 5.0 m/s. It collides head-on with a 3.0 kg m5wf vgl.9e3t eew5-k xass at rest. 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 speac,f d.g+8upcj 4 lc.eed of 4.0 m/s collides head-on in a perfectly inelastic collision with a stationary 2.0-kg mass. How much kineg jc+lcu 8.p,adec.f4 tic 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 statit y2o(/j( y;zk0dp ; regl0;wh mxf5fbon wagon, who's mass is 2m. The bumpers lock together in this head-on inelastic collision. What fraction of t( r(fwd0efg;ypomx5 h/y0;l ;zt bk2jhe 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 travel0;x e * nc8w;xcp38lwolnttg,o e8n: ling 213 m/s in a vertical direction buries itself in a 2.4-kg block of wood a rest directly abceel n;3x8t0lg wx potn:*88wn,c;lo ove it. As a result, the bullet/block combination moves vertically upward.
(a) Determine the velocity of the bullet/block combination at the point of impact.
(b) Determine the maximum height reached by the bullet/block combination.
(c) Is kinetic energy conserved in this collision?

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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,stz ow46nmq (.0 km/h east collides with a 3000-kg car traveling at 60.0 km/h south. The two cars stick together an m6qs4o,wzt(fter the collision. (See Fig. 7-1.) What is the speed of the cars after collision?

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A. 8.33 m/s

B. 13.9 m/s

C. 17.4 m/s

D. 21.7 m/s

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car traveling : u .y;sauvi*uat 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 direction of motion of the carsu*u asy;uv:.i 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. Obje8/bgi d p5;a;dh6k cnfe+aue:azk:.fct 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 momentu;ed5;zaicfban6e.+8 :g a/:k pkfdhum after the collision?

A. 14 kgm/s

B. 26 kgm/s

C. 34 kgm/s

D. cannot be determined without knowing masses and velocities

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A small bomb, of mass 10 kg, is moving to):wnj +)ouu xzward the North with a velocity of 4.0 m/s. It explodes into three fragments: a 5.0-kg fragment moving west with a speed of 8.0 m/s; a 4.0-kg fragment moving east with a speed of 10 wuxz: j+)ou)n 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 orr, 2aor2;gwbyv1 c )wlvj.aj( igin, and a 10.0-kg mass sits at x = + 21.0 m. Where is the center (12c2,lg)jja owwrb ry.vav ;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 of0l0bbq(lmq3 x9 cwy*w a two-particle 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 the second mass of 3.0 kl w* b 9bqy0(lxqc0w3mg?

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, 0r7 jp-,m+n mcv), and 4.0 kg at (2.0, 1.0). Determine the coordinates of the + pcmj7,- mrnvcenter 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 kgm1k qa0 3ule:bmh *tg, .l9t)qph3a ob, 2.0 kg, and 3.0 kg, are located at (0, 0), (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectively. Wha 3hqatbu)k. *mb oeh:lm03ga9,tlqp1 t 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 mass is positioned atpz2 lxdk)*s g*+ zy+kg (12, 0). What are the coordinates of a 4.0-kg mass which will result in the center of mass of the system of three masz2z kgldsx g k)*+y+*pses being located at the origin, (0, 0)?

A. (-3.0, -6.0)

B. (-12, -8.0)

C. (3.0, 6.0)

D. (-6.0, -3.0)

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Use Table 7-1 to calculate the position of the CM of a whole lfbio,8vz r(0x eg including the foot when the leg is stretched straight out. Assume the person is 1.60 m tao8ri v,x0( zfbll.

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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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