Physics Unit6: Work and Energy - 题库网 (tiku.one)

1#

What is the correct unit o,mqs-+q js; x)wti/xe f work expressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s$

C. $kg m^{2}/s^2$

D. $kg^2 m/s^2$

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no mpd 4f: -nof*kvotion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the a:y j5 a a+cuc3vwjjcm*b0tm4 uen5)7tmount of work youa0ac mjtw7u 3*j :yvt cjm)5 ec5+bun4 do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is beini h8wx7w2 d4 -pwc)lsdg held there. How much work is being do8c2d )hxiw4wpd-s7lwne in holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forwan,j18fml*dy4 8zahs. qhloo0 rd at a constant velocity carrying a 10-N object, the amount of work you do qhz *loyn 8djl,14a.o 0shmf8 is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted ver0,q8 ln9ychwm tically 3.0 m then returned to its original po89y 0c,whnqmlsition. If the total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force hiyal.)hkg . z7 ww0lc rg1k6/j9c3we acting on an object do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compar3k(zmhn0iahifc. 0 )o e the sign of the work done by gravity while the a m k iz0h(f.)c3hio0nball goes up with the sign of the work done by gravity while it goes down.

A. Work is + on the way up and + on the way down.

B. Work is + on the way up and - on the way down.

C. Work is - on the way up and + on the way down.

D. Work is - on the way up and - on the way down.

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, brmyd (/tkj :us) 5r;lon a Force versus position (F vs. x) graph, represents ;5djrkbl)u/sy:rm t(

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the workk2e pvlee/t)3ox n-d3wq.mqt-h ,v 7k done by the force F)tt- px -.lqv/wve7 ho3d qkn 2kem,e3?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

D. the product of the maximum force times the maximum x

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; mv^2$ is

A. the kinetic energy of the object.

B. the potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object's k:lh lbd(/axwgl t0j) 5inetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then the object's kinethu7onpuz9 s4 9-wtp, aic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on anvez:z9xnx/ q-rw 5xn2 object is zero, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twim2r0)hme ofzq bx30k8ce the speed of the car. Whi3)8r2 o z 00efqxmkmhbch statement is true about the truck's kinetic energy compared to that of the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of car K. The k;)gi 5wb+cui)y azuo .inetic energy of car J, compared to car Kg+ao uc5 ;ib.ui)y)z w is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speedpoma9kje kdd- hdj+x/o1o11 , v;gb9s. What is ja kk/ e1x11d 9vh;d,jopb- g9om+dosthe ratio of the final kinetic energy to the initial kinetic energy?

A. \frac{1}{2} \;

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a*gy.(vlm)j cyt j6 ki- speed of 3 m/s and a pebble is moving at a speed of 5 m/s. If bom*jk. 6tjg)cy-l vy(i th objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is mv ztiw,r*a:2 ioving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greate *ziwrit:,2 var distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes yt //*t j+fx(3qzmswtkbmp :5 of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skid3tsw(jm/q/k +: x5yp m bz*fttded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass ;w*3; wo/ u+)pdgfc rd.tisx6thmnm )orbits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to thn.hruofd ) *wtxs;)m;i pwtg/6 m3+cde planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energjcgbpq7/wn zrz su29 +k,od08 y principle.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; kx^2$ is

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential enereouo,q nbts +*jdtub *c.t- 34gy?

A. Yes, as long as the total energy is positive.

B. Yes, since the choice of the zero of potential energy is arbitrary.

C. No, because the kinetic energy of a system must equal its potential energy.

D. No, because this would have no physical meaning.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h abovev-uy(gtb dc1 m8 2b6se the ground. A second object with four times the mass of the first i (t c-e s21g8yudbbvm6f released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached trj,+s vpe ;ta*o the end of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass iav jtr+;* s,pes added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical e;4hz-0j7 loyhtb; wqa nergy of a system

A. is equally divided between kinetic energy and potential energy.

B. is either all kinetic energy or all potential energy, at any one instant.

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tr6e51j dus5nh /,ywtd+: ixtdu ee. Compare its kinetic energy K, to its potential energy + s/,51tdidhetdwu :y 5un6xj U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a p-l,nv(k3q- j:sbsk ccar driving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are sk q h7:88c(itcqjy,erliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Whq8 i 8y :qjke,ctc(7rhich rises to a greater height?

A. The heavy object, because it has greater kinetic energy.

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

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

Consider two masses msh67/k3-iedxx. xa a1 xhetkh/o*.a $m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle okf9qa0 ci37zq lsc2(u47 zqsa f conservation of mechanical energy for conservative forces.zcafq 7l4k3a9(7qzu2c sqis0

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top fx,2j*tff: eoof a building, through the air (air friction is present), to the ground below. How does the kinf2x,*ojtef f: etic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic eb4 qom2llt8c,nergy. Do not ignore air resistance. How muchc82tl ,4lqob m gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational potential p (wqy9swvkb6sd(3w0 energy. Do not ignore air resistance. How much kinetic energy did t(w b ky39 qdw0swvs6(phe ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation of energs j,pi6 m5u8nd-g3mp7ce+ri by.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t islmmuhj 6y ,y +hwb+gh:7 je-d(

A. the kinetic energy of the object.

B. the potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct uu6ea9gk*o jkw b j2*7gnit of power expressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s^2$

C. $kg m^{2}/s^3$

D. $kg^2 m/s^2$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is9y*m-)gok vy8(e i ryq not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3rjny 3y+(rz; wsw 7xz*jlu r,; times the work in one-third the time. To do so, your power output mr z l3wyxnj;,yzr rj7ws;u *(+ust have been

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constw3o2xjtvlwzv, ggt, b51 p/5l ant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held tmbxh-hc5 k e4/6 mp9 55kykmzehere. If the object weighs 90 N, how much work was done in 9ke h5mepmx c bzkym-65/k4h 5lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in theh cx;u4cdqm0 / air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weightd4 c0ux/qm;c h of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upyg rlb7vj1trk e0 z; 4)0v4oemward with a constant force of 5500 N for a distance of 50.0 m. Whate gevv004km ;bzyo7 l1rt)j4 r is the work done by the 5500 N force?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force on*uk ,:sat 4usc 50dmxf 5500 N for a distance of 50.0 m. What is the wut:5s s4n d0xu* ,mcakork done by the weight of the elevator?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant forcerb 1on:m:,das w*3aij of 5500 N for a distance of 50.0 m. What ai3 *r,wsn: 1baodm :jis the net work done on the elevator?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0ez jf7.,socs3a8sh x: m up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp, ir/7bg 41ch*q ff/-x khn . ;w+zsslfptnclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy surface (assume no rnbp.a/ ms) bj71fua w17x)gtfriction), with a force ofm nru). t/p1g1 bw)jsxa7 7fab 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object ,:ea,ll+ ce duin the direction of the force. The graph in Fig. 6-1 shows the forcu:ae +ec l,ld,e versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6-4 pp w4gwqdzr *35m1cj1 shows the force versus the object's position. Find the work done whenrcd*4mpgq5jzwp4 3w1 the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the diy o03/oc6tm xwrection of the force. The graph in Fig. 6-1 shows the force versus3oco 06/x wmyt the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction ofkazm3 qq5z*u0z/u qg+y2mg*-pnip (j the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work- j/ipyu2*agq*mg5 q(zk0 u3q+z nzpm done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at r:-h ud.-tct5b/cn (sav ppv5 aest) across a 10 m level surface. Whnh -apbvtus(: -t/.vpc5c a5 dat is the final kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at rest)knbi1 j3hu+ma 6 .jeg ltbdms7q 4w,21 across a 10 m level surface. What is4un b.6 2lma73b1 sk,1dg+hqewj mt ji the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a spe9ghr/h71 +bs.r-w le +cpv yqjed of 5.0 m/s. How much work is required to stop the mass+hv -j ry/qw9e+c7sh. p1blrg?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initiak17 n;ymd k c pwktghkmr4(3,w9m wd48lly moving at 25 m/s, what distance is required to stop a car moving at 50 mh;kgmpw4w(d147 ncdw8 mtykk 3 ,k9mr/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is cocqnp 9 jg4zs86-andjty5u1r.o ked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligiblj-a4 sun tzpr9yj15o86.g dnq e mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a6y 6-alcqbv 8o9 aj;wav3cdj1v,xtn7 vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?9cj-adaxvolv18w;c avb6y6t q j7,n3

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, str(y0;apt-+hzwkc x vkrk78y npm-m;4 diking the hay with a veloc78t+kwk-z4 ;; xpn yc(-dvyhp a0rkmm ity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height jdvi9 mpo-:l,of 7.00 m above a floor to a height of 13.0 m above t,o9 :milv -djphe floor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m lo tccsr/vri8zjfe j*gypw.0 90x-.qh ,ng and rises 2.0 m. If the plj/.8r*0jccrv sy-ei0, pwhz 9f g. xqtane is frictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes theofwvwr835:qgry ; mb* spring to stretch 2.0 cm. What is the spring consmf3; wo:w*r v8brg5 yqtant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a sdv eu :fz5m5g)p.7w onpring constant of 60 N/m. How much potential energy does it stumzwev5 f5ogn.)d7:p ore, when stretched by 1.0 cm?

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to comprvnn8 6i5-*yuotpm. ,j kqet -aess an initially uncompressed spring with a spring constant of 25 Nue kt-,n6.-p5atnq* vo i y8mj/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N/m from6p uf1)6s; gwq/fowqu x = 0.20 m to 0.25 m? (Assume the unst o6sq; w1g uufp/fqw)6retched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constan7 -/ nqp;a zbv(oyaf2et of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an additional 4.an 7v-/(2qeby;zopfa 0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50 ( f. ovy,9p-inta-diy*:jvhs -m high slope. What is the speed of the slier on reaching the bottom of the slopeyfi v, tnhja9( *v d:pi-o.y-s? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the tf0+3.zown lgqwmdbkh :r,*r 4op of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will srn mr0b*,g +wqfk3wz4l.hod:he be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bottom, it has au,iu vb**hak7 speed of 9.80 m/s. What is the vertical height of uhv,k 7 *biua*the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it s;nc/p7wk.v y is 0.70 m above the floor, its potential energy exactly equals its kinetic enerk/ycn.p;wv7s gy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing )+gtnmt8rm08 a2v tlj10 N, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy )t 8gt2ltnm ramv0 j+8is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the grfv7 i1kjy(y3 z0ga)w z)x8v bzb 2hyl7p.,lvqound with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical hei0,vk8lbxv2( 7zg3jlzqz ivyy.)f bh )wa7 y1pght, relative to its launch point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the bottom ofakhz60yb) a o33h, p fzb6p7re a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 ok3h3b76p6a0f,a bp hz z)ey rm above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a ponhif*nm+1-e x int 45 m above the bottom of a dip (See Fig. 6-2). Neglect frimn nxhei*f-1+ction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above i971mplu ,con the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Negmncilu19o 7 ,plect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottom of its swing (paft.i3 ( ily1dv4f4wy oint

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away x/ b8jlyo3iwmx+. dt 7from the vertical axis and released from rest. What will be its speed at tht 8 +dmx7x3./jyiwo ble bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an i8k8zbmdz 7*5 mlwr p ).v:qsjinitially uncompressed horizontal spring wib8 p 8.*mzslwmk)r 57vj:qdzith spring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to stop for a*vp+vvp 2b2ax- hy td- red light. What work is done by thvahp2+v-t-vy *2dbxp e friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horizontal*dmwrht jl s6vp q4nmb -a 66r8uv(5v8 surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before comwm 8t p l5uv46vrm aj8qnvh- srd66b*(ing to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is movings 0ko:j-tdcw,d/y li 0 on a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.,/ d0syli-j ot:ckd0w50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg makxq4yu0xafo z-6 h8a-fhp9y,ss on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If th9ffh0hxka-q 4yy6oz,8u x -pae mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m hig;up3dg sxo) d1p8;luqw 4p mw.h slope. If the work done bpsx4m1ww u;udp8 o ;q gd).3ply friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is 4.0 m long l6n sa)andpgyh59d j(/bx .a:mh 3o,iand rises 2.0 m anyp:(a mh5h)j3 b ial x6os.9dd,gn/. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined at 20e ab28jbtc rg (dv4ove horizontal. The coefficient of kinetic friction between the mass a j cb8d(tgr42vnd the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from o+ dnwg8oz k9*-vh)hka height of 10.0 m, and strikes the ground with a velocit*whk+o8 )-dv 9hgnozky of 7.00 m/s. What average force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a flight of stairs 101z7c 8g+jp 8 g lg:zh6ejm-nsy.0-jg:nz gg881scm-p7h 6zlj+eym high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a coh+b zg14mzt 4bnstant velocity of 5.0 m/s. What power must be delivered to the object by the force?ztm4 hg b1+4bz

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a6a0qq3y yc(v *lhz jcxp7h44j 1.0 hp motor that runs for 1.0 hr? (1 hp =v4lq7 ( 0 3czpy6hjay*hxc4jq 746 W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. H- 4 2ilwnqx,s yl:*anaow much force does her foot push with when *wnsa,i q -2a:xy ll4nshe is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What i i) yr+qc/ndwz(nng; /s the average power delivered b/nc(;nqdwygr /in) z+ y the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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