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

1#

What is the correct unit of work express;b qgx789:ed;pjpxfi r3,ne wed 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 therek zx1szmccwi6: p287e is no motion?

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,u 6 tcs wyi48t1d6o;1ntu/ibm the amount of work youittu4dm81by/ n16ot6 uiw c;s 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 vertically1knq:zb v4.qzz2zn 1lkj*b s7 and is being held there. How much work is being done in holding the box in2z bvzjqq.*k71nb 4lz ks1 n:z 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 horizontallyba -iz/oq-g3)u.ushwn3pp 5v .jg) pl forward at a constant velocity carrying a 10-N objectv.aqhj- .pbipponsl5 /z)w)u gug 3 -3, the amount of work you do 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 vertically 3.0 m then rei(zsare8mk1 a)bi (mqd9 u q4t9ad;3g turned to its original position. If td qiaa)9ez1r4 sm ; da((mgib39t8kuqhe 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 acting on an object do wonp vss c0l;6t5rk 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. Compare the sign of the work done by gravity npjsmh ,)9m zl;hpnpa:1 f+m (while the ball goes up with the sign of the work done by gravity whi)mj 1n9zlp as+m hmf:h;(ppn, le 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, on a Force versus position (F vsg9 kg g(elsg6g:o g+4llby/8n. x) graph, represents9eog8: sgg6k ll/gg4 nglb(+y

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 positionnri tm3lebsg 4g,gp1jm*2 2.k (F vs. x), what represents the work done by t*nmp,j kbl g1g4m2eri2g.s t 3he force F?

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 1wqt1n zhr+xb;c(emlx( s+b 7;j i*kwis positive, then the object's kinetic 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 isl*xm n lkg/: q+agb(cb/):;x3hrbjsj negative, then the object's kinetic 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 an object is zero, then the object's kinetic enex)l reygfu/1k8f8av ,rgy

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 twice the speed of/nn;a/5yqfp;hm hjyc*4 .g zw the car. Which s wfyngc5ahq /4.m/;hnp;jzy* tatement 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 Jfmu vpq6qs,2f .1wo4w ;0tecn zpn7.g has half the mass of car K. The kineti7 q n.uzn6mt4q0g1;evw f. cs2o, ppwfc energy of car J, compared to car K 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 blc0z 3y x89s; nsj2bsb-r2gt pounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic0sz39nb -;srxs8ygl jb2 cp 2t 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 speed of 3 m/s and a pebble is moving at a speed of 5 m/s+ jbp(*0clao9xwel13ss s8v g. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the r(0s pw l je +b1lox*a3v9s8csgock'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 moving with speed a,: /o80s8nbg:onrdxqv17 nvp *bkkg 4.0 m/s. Both objects encounter the same constant braking forcen8 n:k8bg7vbr1x:os vnpk d 0o*,q/ag, and are brought to rest. Which object travels the greater 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 of your car in a panic, and skid a certain distance on : 57ldgqz g1+:3 fzi:6gdptyf ta5a ava stragg+ layd:g75t 6a5f:d 1pf avzi:t3zqight, level road. If you had been traveling twice as fast, what distance would the car have skidded, 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 m2t1x ocnhg (n) 0apb-dass orbits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic energy?o-nhdp0c(gta bx 1 2)n

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-energy pryg+n-9)pz ar ,l(p(c mkjy z-kinciple.

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 negatii fa ap06+z-flve potential energy?

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 above the ground. A sj 4n:ncx vamtan.oa3ip7b 3n *ur 7(4zecond object with four times the mass of the first if released from the same height. The potential energy of the secondz4tn. :vpnnc m 743xb (a7au*joa3rni 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 to the end of a spring causes it to stretwf8qy-o;( w8 .dyeqy uch 5.0 cm. If another 0.200-kg mass is added ty (eyuf;w. -y8qqowd8o 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 shhp /r)6iyj9dvu0.h energy 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 tree. Compare its kn)4dcamyq; j-.2 mqrmoth6q 1inetic energy K, to its potential energy U-q;)6yqa41nmmqd m. tc rh2oj.

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 car driving up a hi318jk a )eddsjc pfg*- 8hqql2ll.

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 sliding kv 9)v,nsuw(vm vs77cwith equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a gre7wucn7vk (vs9mv,vs )ater 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 mb9seqiw / ,35g7d cwk w,qct.$m_{1}$ 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 of conservation of mecham l.5by .zc654hcfo: zztf y6mnical energy for conservative forces.6.yctcf .f y55 m lhb6m4zzzo:

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 of a building, through the air (air friction is psp:v duzbc(o1/qk rac)po1-0resent), to the ground below. How does the kinetic energy (K) just before striking the ground compare tocq p1spua:r1bdko(o /zv)-0c 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 energy. Do not ignoreie*0x 4fic- ji .zh,r -d5ocxr air resistance. How muc,ixd-jr. 0ixf rc-4oeczi*5 hh 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 diw6xhgal8 22jl7d 4al cstance and loses 30 J of gravitational potential energy. Do not ignore air resistance. How 7a6c4gdhlj2 l8 ax2l wmuch kinetic energy did the 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 conservadn du(oope45 ( ah4v/a/ 9rqhoi/,hiation of energy.

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 ismn jr4zx o15a37,auwvubu9 , q

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 unit of power expressed i x 6qxska00el1n 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 i7*fqkgr-) j :a0s8h h-ur;e zynt :ahvs 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 3 times the z 5ocpqr4r5ev7i qvc h *-0lf(work in one-third the time. To do so, your power f0 ( -z c5re4*v ch57qrviqlopoutput must 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 constant acceleration, the car's en(0nkpop;dte fttx/+/7x 5 r nqgine 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 there. If the object weighsm, a4gi6 ;xa)r,7uel/oaiovq 90 N, how much woru;/ 4,qlvag mr)ie6a,o7 oaixk was done in lifting 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 the air a distance of 1.0 m, at a const1nam/;2g9( h lzszom hant velocity of 0.50 m/s. What is the work 1n; h2h9m mzosz/ a(lgdone by the weight 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 upward with a constant force of 5500 N for a di mkuit7q-m6 k/ n/j)lustance of 50.0 m. What is the work done by the 5500 N forcnu k6ml -)qm/t/jik7 ue?

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 orcyi 20v1lcp9 g.czj9 f 5500 N for a distance of 50cril.9p c1 2cjv0gzy9.0 m. What is the work 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 forosrb(- 7dt4ldbkxw0, ce of 5500 N for a distance of 50.0 m. What is the t 0s d-r7o,bwkxdb(l4 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 6.0 m up abxo m k ptkvh8: , ax:*q.x2(hm)zvgi1long 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 g s41:l4gml;p0fg uzz a ramp, inclined 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 3s wp kvv1z9a*wg1xy xn+r +o:no frictionnpv: ++zysvw1kw*go 913r xax), with a force of 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 in the direction of the force. The graph /oylb6t3qn858kqk; 7cwubf 6q/ ao qe in Fig. 6-1 shows the force versus the o/f uo b cbq8ta6wq6l7/q ykeqo;5nk83bject'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 2)k yitxwd8) /j64/nmlxzlh jthe force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves frwjyj)tm/d 2ln hzx84k) x6l/i om 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 direction of the force. T lg-t5pj6x l 70o4tbeux-1wshhe graph in Fig. 6-1 showt4loge0 1-xjpw l-u56tbxh s7s the force versus 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 of the /1nf-8fj g eavt z3za ;kc5vs/force. The graph in Fig. 6-1 shows the forfact j z -a3;ef1ngv5v sz/8/kce versus the object's position. Find the work 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 (in5hf9 f(w. nbf z4x(l2:ouvnssitially at rest) acrossxfn5s(sozvw(fuh9 .2 4l b:fn a 10 m level surface. What 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 h- ,4cfo-a f8zo oo;jgw6 jv-va 55-kg cart (initially at rest) across a 10 m level surface. What i;6 z4oo,j -ovf vjog-w-8hfac s 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 speed of 5.0 m/s. How ml1: *zirlz.ptuch work is required to stop the mass z:*t1plrzli.?

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 initially moving at 25 m/s, ;osgda 8p4rbubu :,;r ujr 6s6what distance is required to stop a car moving at 50 m/s or r,gd sbj4:r; 6pb68aus;uu 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.i1ucd) nk+ q(a It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what s)k(dun1+i q acpeed will the dart leave the gun, assuming the spring has negligible 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 l2gw 00h g1iscand a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from restw2 g1l 0h0gics, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

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 shotv xbjd5rl n9.l*x2 m5x horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stoppingxd 5lrm*9 x5l2 .jnxvb 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 8ku. k33a e1hclu :4irm df-cppn;x*pmoved from a height of 7.00 m above a floor to a height of 13.0 m above the fd ;3ukf4pcx8:ri -anc1pl *e ump k.h3loor. 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 oa r3qr rw8n1y --oo0vb5aoo8 an inclined plane. The plane is 4.0 m long and rises 2.0 8oo8vqo3r1ybr- wa ar0-on5om. If the plane 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 spwr1 b )xd*0hst2xyq8zring, causes the spring to stretch 2.0 cm. What is the spring constant?8t xwd2*zxy1r)0bq sh

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 spring cof: 8c nv2 /rdax4uz+g+kbexc)nstant of 60 N/m. How much potential energy does i/2xdu4)c8ax egv ++cr bfznk :t store, 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 compress an initially uncompressed spring with a ;2 psmk1;h5nvo jyk48,r2xh) dxqhl y sy1rh ,oxjl5k 2 ;v8p;4ky)qd2xsmhnhpring constant of 25 N/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 ipq** +oitc(.)z07sta4ttv v oe a0ia constant 40 N/m from x = 0.20 m to 0.25 m? (Assumepv tiao0ie*v)*o(0q +t a tz.cait4 7s the unstretched 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 constant of 15 N/m is initially compressed by my9 e a*7ctjd63.0 cm. How muya7jd m e6c*t9ch work is required to compress the spring an additional 4.0 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-m high sly:r, 0br3o3v.fz- zyu+e2akrts -ix;z tj c, nope. What is the speed of the slier 3 zy3s,-u te;j2nkc r+z r0,zbort-ayv xf i.:on reaching the bottom of the slope? (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 top of a hill with an initialds46zi *,qz4j rpv;bz speed of 4.0 m/s. Neglec44zbq*sz j i;p6vz,drting friction, how fast will she 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 inclk6 l0 l/1kw sth1jwk/rined plane. At the bottom, it has a speed of 9.80 m/s. What isjrls /k6/kt 10wlkh1w the vertical height of 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 floz am2khfezlc4a*- (-k or. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is kz -lkm*-(e az2cf4ah 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 10 N, blasaid(0+kzam (ets straight up from ground level with a kinetic energy of 40 J. At the ex0zdaea(m k(i+act top of its trajectory, its total mechanical energy is 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 ground with a kinetic energy of 220 ;mq -6xilcqk gc6 1*wpah(a3d J. At the highest point in its trajectory, g m(* pcaak;hidl136c w-q6xqits kinetic energy is 120 J. To what vertical height, 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 ofna33o*6/o sryqfko0e 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 m above the aor0q6on 33 s/e* fyokbottom 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+gzl-i1 w: vqo of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what :i+qow-z v 1glwill 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 the bottom of a dip :ho iqwdv)5 wqn0mi bw.j-u-+s s7v3bdq: 5hx with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top ofv:ibqs0 .q+m)--3buw5 :hjsvowxd d 7hn 5iq w 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 (pif9n;f,.bvlc 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 from4/nf m dz.phr- the vertical axis and releas m4hdfn-.rp z/ed from rest. What will be its speed at the 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 initially r*,dwu- (jqi s 4ewd )rfnubi 89sx1v/uncompressed horizontal spring with spring constant ons,v r1ds f-) q*w(xi4 w9dbi/u8eru jf $2.0 \times 10^6 \; N/m$. 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 he8 j8d+ iduiyy2r 2000 kg car to stop for a red light. What wo +2dyu i8ydi8jrk is done by the 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 ,:r ivcgl7 (ucand a horizontal surface is 50.0 N. If the initial speed of the objec7i:ul c(cg ,rvt is 25.0 m/s, what distance will it slide before coming 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 moviv/ytvi sdl /9.z32 5)c hddyhdng on a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How)h szdd li dyct3hdvv 95./y2/ 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 kc geoi az x2sd+5 s(+fzi5y-e6,cp1g a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a dista pe (++d5f z sxgcz5giy6kci-,2a1eosnce 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 *o3 .aoyq6guzvd(3q zthe top of a 50-m high slope. If the work done by fr *z6oougd3zqvqya ( 3.iction 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. Theep uu wt.k1/8p plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to geu/pkp8e. wt u1t 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 plafxmcc7)fw0 h41 ev9y y:o9q ajne inclined at 20e above horizonta7f109jmeh xc)y qco 9fva4:yw l. The coefficient of kinetic friction between the mass and 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 a height of 10.0 m, and s4pr 8 8m7excultrikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it7p8ec8ur l m4x 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 yl6 p8aqm-6vkstairs 10kp 6yq6-lm8 av.0-m 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 constant velocity of 5.00k 79d7ny6a+smij9 m7uipp+g8 df htt m/s. What power must be delivein0dgjt +7i m9 kfu8yhdp9 tp+7ma 67sred to the object by the force?

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 a 1.0 hp motor that runs fo cj:m29j1vw tbr 1.0 hr? (1 hp = 746:mj j1 bwv9t2c 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 r/fzfv+ey wk1: ate of 500 W while riding. How much force does her foot push with when she is traveling at 8.0 mwzvf :1y /+fek/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 is th8i1 curni+c: qtp s(kq2t g w1r.+np(ae average power delivered by the engine? (1 hp = qw:n .qci r k(8 a1scpt(+tip2ng+ru1746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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