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

1#

What is the SI unit of momentum?mnnc):p/ .ow.,ghh fq

A. Nm

B. N/s

C. Ns

D. N/m

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When a cannon fires a cannonball, the cannon will recoil backward bec1ddxf n l7+jow: (wrp3ause 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 con0 s0y-yerpvp:stant speed. The car is open on ys-evppyr:0 0 top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?

A. It increases.

B. It remains the same.

C. It decreases.

D. cannot be determined from the information given

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A child falls sideways off a,(vi(yb 2s9 qtu*vaxa sled while sledding on frictionless ice. What happens to the velvsut,y ibaq(av9* 2(xocity 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 mass. They arw6is/0o4 jgj u0bka6h e thrown with equal speed against a wall. 46/g0 sbj ai0ouhjw6kThe 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 q188znfjvn4fkpu7a0 )guxv 5 a momentum p. How would you represent its kinetic energy in terms ofpfugvn u)na84zkf5 q80 71vxj these two quantities?

A. $p^2/2m$

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

C. $mp$

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

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you pitch a baseball with twice the kinetic energy youcwd0t;so7z; :vfr )p ;k1knux2j ;r bz gave it in the previous pitch, the ma ;jc v;f7ukztn10do:k; )x;b2wp sz rrgnitude 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 in terms of momegd5xr 8hh: hj4,i**jk qst:u2vid j*hntum.

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 mb0e e**c5 km q) d,onvz, fysmwh3t6p-7mefd(omentum.

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 curv1 .ttn y 1d*4gqpm3wzve on a Force versus time (F vs. t) graph represents

A. impulse.

B. momentum.

C. work.

D. kinetic energy.

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Which of the following is an accurate statemenp mzbu7bt;0x;s5 8f w0oyl9 fat?

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-o,bf*az a/ie 26 uz7 s2 f.fnwx jv7t,yri;ae;cn collision. Which of the following statemci , , f62;s*;reewzyjafb.u77 /2vxa zi anftents 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)ww 81mcgxl7,q are 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 its coll7 c1wwgm8l,q xision 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, collidt)1rfu)+s coles with a stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowlyf l+r1o)c )tus to the east. Which object experiences the greater magnitude impulse during the collision?

A. Neither; both experienced the same magnitude impulse.

B. the Ping-Pong ball

C. the bowling ball

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

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects collide and bounce off each other. Linear momentuv0byv; tx3z dft1 my6pv.y-9m m

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 4.0bf+ t.j) :bi1nsd; c:edymju+ m/s. It collides head-on with a 6.0-kg object moving to t+ bdmn .eyt:d1fcsu i) +jbj;:he 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 ;(c ymdlb8kdw:rh* w/ at 2.0 m/s tackles head-on an 80-kg halfback runninc*;/8mkdb w:(rhdwl yg
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 x3k c d7j.sje -6jpiy*h 9jrss 3/a0gpconserved, then which of the following statements is true abc-pgrx j.e k6jspy3hj0as7i3 sj *d/9out kinetic energy?

A. Kinetic energy is also conserved.

B. Kinetic energy is gained.

C. Kinetic energy is lost.

D. none of the above

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

When is kinetic energy conservedn) 4si/m2gn vl?

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 3spfcy;g o//hcue ball hits the #5 ball and stops, while the #5 bap og/c3/fys;hll moves 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 with a speed of 6.0 m/s collides with a heavy eq5, : t fx8nlspvrd8:yxercise ball at rest, the beach ball's speed after 8td,r:5 qfx p nsl8y:vthe 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 (riq ;m2h3wjf collision with a stationary bowling ball in a friction-free environment. If the collision is almost perfectly elastic, the speed of the golf ball h2mjri3; qf(wimmediately 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 colly ozc;i bsuqkd)u q1 +1s(s7c.o5fnq4ides head-on elastically with an identical ball at rest. What is the speed of the initially stopped ball.1c45q( y1) bosqdz nicss oku+q;fu7 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+rsv2mk /zur0 8fp0soop1 4et speed v collides head-on with a very light object at rest. The collision is elastic, and there is no friction. Thrmsuoo020kp s + r4pte8z/vf1e heavy object barely slows down. What is the speed of the light object after the collision?

A. nearly v

B. nearly 2v

C. nearly 3v

D. nearly infinite

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very light object moving with speed v collides head-on with a very heavy obb-vow hgels /*/mt; c7kjlc/1ject at rest, in a frictionless environment. The collision is almost perfectly elastic. The speed of the heavy object after the c/hb-k/ /ctcmvsl*gwj7l o1 e; ollision 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-on with a yellowt /svrqh7h 8i 1r11ris ball of equal mass moving with a velocity of -2.0 m/s. What is the velocity of th1h1i8 ir/7 s1qshrvtre yellow ball after the collision?

A. zero

B. +3.0 m/s

C. -2.0 m/s

D. +5.0 m/s

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A very heavy object moving with a63r1jhk*viw velocity v collides head-on with a very light object mh31rai j wvk6*oving 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 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, then which cg38y: 7lych/y s0nseof the folloscye 3l8 ny/y7ch:sg 0wing statements 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 toget/a( :u bqwhxe m:/lh5uher. 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+ohjhy7 htw ;o3;ng1v,( f8td c,huso right at 4.0 m/s. It collides in a perfectly inelastic collis t f ;ono+gc(,d1j hy; 8uh7hhsto,vw3ion 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 s4s ct0zom*-bo ticks. Which object experiences the larger magnitude of momentutos*4-c b o0zmm 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 baosufgq*7+ .p n3cot3d*1bn eo ll 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 70iusp(+9.pj d6b v;g qikeo/dplw8- 7vuvtbof the following statements is falsep+bouv.-pv70 p(t vbli9gqk 6/i sdu ;7wejd8?

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 statemedataj)3 vg 18znt?

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 in order yfi -l y-3cle1to

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//ry q pq/vxc4, releases a bomb, which explodes before hitting the ground. Neglecting air resistance, the center of mass of4 /vycqx/ /pqr 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-o- /28n g cxd ;ewvdp8vi8i*udk3fi go*n on a level friction-free road. The collision was completely inelastic and wc/ki*2o xi dve -gngp8;ui*8 f3vd8dboth cars 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 ghe ei,3:j r:lparticles.

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 tr+u3*tyia 1qh -cf9fl c9bsg0 daveling 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 magdy03 x q*awl5(syzx(snitude of its momew5(ss(yxyxq30da l *zntum?

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 /ywx+-u0;p zwdku 1 imfrom a height of 12 m. Its momentum when it strike01w-k z+/ iuuwdy;px ms the 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 perpenujm+ot)ocrz ly 8d.44wjyr4 0dicular 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 the total momentum of th+)4td4r0yo jwo48u jr. mz ylce 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 horiz )7zo)r. rlvvxontally at 30 m/s, strikes a wall and rebounds at 24 m/s. What is the change in the momentum of tlrzv v)r.)xo7he 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, init i9an.nxddk9 9cco5(z4 s qe k2ad+o0dially moving at a speed of 12 m/s, is struck by a racket causie9dndoizk 9x scd4(25aq +n0a 9dck.o ng 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 machpq) 6bn1;yjtae q9ul3488 f 2inkbaz7n *prdj ine (excluding the baseball) is placed on a frozen pond. The machine fires a 0.40-kg baseball with apk) l 21fi7b trjdnan p n6by;a*q838jez4q9u speed of 35 m/s in the horizontal direction. What is the recoil speed of the pitching machine? (Assume negligible friction.)

A. 0.14 m/s

B. 0.28 m/s

C. 0.70 m/s

D. $4.4 \times 10^{3} \; m/s$

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 70-kg astronaut is space-walking outsidetrw n 2l w-vny-ex0,9y the space capsule and is stationary when the tether line breaks. As a means of returning to the capsule he throws his 2.0-kg space hammer at a speed of 14 m/s away from the capsule. At what,2l e9yvx0nrtyw w --n 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 a9fdw 2blc/ a .kl66 sq:xzys7e large object at rest. The y:wa ql fs.zb9s2cd6k l/x 76esmall 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 onbe hx :)t*q0: d7zwp1mxhk6gy ice at 4.0 m/s to greet your friend (40-kg mass), who is standing still, with open arms. As you collide, while holding each other, with what speed do you both move off togeyx:)h1q7:kt*pebmdw 6x 0 zhgther?

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 u nx( .q ox1ccpgo448zto the right along a level, straight road at a speed of 6.0 m/s. It collides directly with a stopped motorcycle of mass 200 kg. What i.qgx1 cxo8z u4oc4p(ns 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 stoppe*lgp9ubw*, utd car that has a mass of 1500 kg and they stick together. What ,*wu* t9ugplbis the speed of the cars after the collision?

A. 5.0 m/s

B. 10 m/s

C. 15 m/s

D. 20 m/s

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A railroad freight car, mass 15,ax0s 1axwb 4pahk 25gw +jc/.o .xrn8m000 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 and with brakes released. What is the speed ofwoa rg5.a4jpb0hx18 knxx2ac /.m +ws 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 withg rfvv6 m8x0y(,- n jgt4/je4h+0tcgw x txho/ 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 fast will the car be4hj6+ hxo-,m(4yg/r/ x0gtxvvnftjt wc 0 g 8e 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 (with r+ ;n( mgtb luj+r9.n9w9ftlm lespect to the log). Wn9b. l m(lrut9+w9;mgjn t+l fith what speed does the log move, with respect to the shore?

A. 0.24 m/s

B. 0.30 m/s

C. 0.48 m/s

D. 0.60 m/s

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-N force acts for 3.0 a(t ,lbs9x c,htco+3r s on an object. The force suddenly increases to 15 N and acts for one more second. What impulse was imparted by these forces to tc+3b(s ,axlc9,tohr 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 2.07t*qxmsjm: .li -ew f, s on a 6.0-kg object. What is the object's cqi*.7xmt j-s lmwef, :hange 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 x5ch e/8pj*vvnv3;) z ny 9jnuvkhw;, the right at 30 m/s, collides with a brick wall and comes to rest in 0.20 s. What is the average force thzcve/5vkp3;,9 j *vhnyn wujn ;h8 x)ve 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 2fu-tpoqo914 a 0 m/s. You hit the ball back along the same path, and at p-oa4 t u9o1qfthe 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 the ball right befo jcpvma*;+l c45f.(rv lscq;ere 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 taall;v( .rvj4fcec + c*ps5q;mble top lasts 0.15 s, what is the magnitude of the average force exerted on the ball by the table top?

A. $0.67 \; N$

B. $1.3 \; N$

C. $3.0 \; N$

D. $6.0 \; N$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A machine gun, of mass 35.0 kg, fires 50.0-gram bullets, with a muzzle velocit /y32 dfzjba;vyfm)0yy of 750 m/s, at the rate of 300 rounds per minute. What is the average force exerted on the machine gun mouyz)f yf2 v;0j a3y/bmdnt?

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 building in order to kntv;qo/+vi f5zock 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, ass;vf5 viz/+toquming 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 -8q6 up+kntawlb w8 l7drainpipe at the rate of 120 kg per minute. It falls 3.20 m to the ground. Assuming the water doesn't splash up, what average force doesw aplu6qnk7b lt+-88w 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,n r/ft .*:.sv0mvsuoi;tp cf p4j2l w4 achieves a velocity of 40 m/s after 3.0 s, when fired straight up. What average thrust forcvw.*rtntosi.0ff4; mspp:vcj l24/ ue 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 masgs/- )//qzxarc 6bdngmzqast 6fn) 9/ses 60 kg and 80 kg, are initially at rest in outer space. They push each other apart. What is their separation after the lighter astronaut has /dq/ -/fatxm)qg n)6zna c gr 96szs/bmoved 12 m?

A. $15 \; m$

B. $18 \; m$

C. $21 \; m$

D. $24 \; m$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 3.0-kg object moves to the right with a speed of 2u 6ufl(t7oed/8ar 33ukxz nw 6.0 m/s. It collides in a perfectly elastic collision with a 6.0-kg object moving to the left at 1.0 m/s. Whatun ftzl 3kua x 7wd3r8o66(ue/ 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 vv0:ye+ec lc -m/s in the +x direction makes a head-on elastic collision with a 0.15 kg object init0 cev-e +cv:ylially 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 r/dt 2;s77egmb- 9n fyc sv:vmo7x-lddest. The bullet 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 t2gl/7cb-:oy 7dnf ;vded7 tvm9s-s mxhe 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 awrl u,4 l)dqaw6fh 4siqn+/y7lpha-particle (which consists of 2 protons and 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 mndh74 l s6+fq, alruqw w/4i)yass.)

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 stan t1k7cu9dm 7 nhri:x+tionary ball of mass 100 g. The collision is elastic. 7m nx1cn7rid+9h:ukt 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 moving toward the east with a speed of 3.70c.yvu7whabyn u//+q8 m/s collides head-on with a 200 g ball sitting at rest. The collision is perfectly el uw/.ayc8bv+uhy n/q 7astic.
(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 a axik-1p(2uywytub f+u 4)cs4 3.0 kg mass at rest. If the collision is perfectlyuyfk-44w )ti uy21+ px s(cuab 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 hc mp43 +a9wo//pz jlvto the east at a speed of 4.0 m/s collides head-on in a perfectly inelastic cch9/34apj +wmzl /op vollision 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, st p+ro:t8 :-z,b obhuqxrikes a parked station wagon, who's mass is 2m. The bumpers lopq: u8-+boxoh , rztb:ck 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 in a vertical direction buries itself in a 2.2b0 kaneo;))e usom/d4-kg block of wood a rest directly above it. As a result, the bullet/block combination moves vertically u/ an e2)) k;beusdo0ompward.
(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,kot/. pza(c2 rgm*5n n4dzpl .0 km/h east collides with a 3000-kg car traveling at 60.0 km/h south. The two cars stick together after the collisio (,gz d*plrok m4c.paz5 nn/2tn. (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 j m;n; btv9)hoat 90.0 km/h east collides with a 3000-kg car traveling at 60.0 km/h st b)n oj;9;vhmouth. The two cars stick together after the collision. (See Fig. 7-1.) What is the direction of motion of the cars after collision?

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A. $36.9^{\circ}$ S of E

B. $36.9^{\circ}$ E of S

C. $53.1^{\circ}$ S of E

D. $53.1^{\circ}$ E of S

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Two objects move on a level frictionless surface. Obq skw q,2wm 3o:-dgvt6ject A moves east with a momentu3,2 v-gd6: wsokwmqqtm 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 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 velonbpc uy bpa8hh+17-;r city 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 m/s; and a thi-bb chpa8r7u+npy h1; rd 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 atw yv3p 9m4s2hf x = + 21.0 m. Where is the center ofp23fys9w 4 mhv mass on the x-axis?

A. +7.00 m

B. +10.5 m

C. +14.0 m

D. +15.0 m

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The center of mass of a two-particle system,+qmgub5mq/s+ p; ykq 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 3.0bsy; +5+ ,gqmkq /umpq 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.hav3zggk64 x +x2cfb9.2vlyb 0 kg at (2.0, 0), and 4.0 kg at (2.0, 1.0). Determine ybckvz9xfgh24l ag+bx.3v6 2 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 (0, 0)ai y+hw3xc 7-tjc*h(s , (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectively. What is the location of the center of mass of th j*s(x a73ht cyhi-+wce 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, 8jy2um pw )a1a+bhu(x 1.0), and a 1.0-kg mass is positioned at (12, 0). What are the coordb1h)+(j yx au1up2a mwinates 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 a2 d -lb7ag 6rs3b.wi4(jy6w ak0et bdq whole leg including the foot whj7wye w-k2it3gsbal a4 r0.6d(bbq6d en the 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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