Physics Unit6: Work and Energy - 51fly国际课程 (51fly.win)

1#

What is the correct unit of7(1bsqtrre w 0 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 syst:l4soh, 0wfstem if there 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, the amobmjx u6hp7e9y:c,- amj-v+6uwf gs1md;e, bqunt of work you do bm+j;,1va-6e dg,qp 9:u- jybuemh sw6fc x7m

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 being held there9flw/8o1 v;q v(arbg 7nzh*ri. How much work is beinb1n7 v ;/afrw*( v oql8rzi9ghg done 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 forward ay,n8 o tcf9f0 ez7;j 5skqghd+t a constant velocity carrying a 10-N object, the amount of;yqfz t j9e7ckn f50 s,ghd8o+ 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 returned to its origlp5 ou qtj*3b;+eod)f inal position. If the total weight is tb3o+pu j;e*5odq fl)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 ;yznxn/,ij*v 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. Compare the sign of the work done by gravity whiaes,fyv es-9 acc o;v20 .hw*xe; yx0dle the ball goes up with the sign of the work done by gravity whil;c0* hv-wd9av2y s.ee osy xf;ec0 ,axe 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 vs. x) graph,kt q9432u :+wpxdz z:o)k cvrt representsk3c2rp +xqz:z4) utw: vtkdo9

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. xfs4)hdm/0 dpd kz;q;o), what represents the work done by t ds q;);odmz/h4kd p0fhe 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 is positive, then the objecq n4 qm-v9 8*gbdfp;uot'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 is negative, then the ob8h-lyjpbp u 5rma,q95 ject'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 kin*o-3 * jnfene8 y0lo/lvyuxk1z 6ze6oetic 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 movingf( z ijily6(l7 at twice the speed of the car. Which statifj(zl(iy7 l6 ement 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 caq972fsi4u zidr K, and car J has half the mass of car K. The kinetic esfi24 iuqz97d nergy 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 boun7l0e+m0 qid 4.qwe6r;e2(y ohmx dyi vces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kineqx4i 70e;e2whydy 0l.r +mvdemq6 oi(tic 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 moving4h(mg8jslywg vvf v-gu57 b;5zy,m-n at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ran;vbzh m4s(vm ,wgfyyl-5 g7u58g -v jtio 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. Aca,n nn63dp v8sh7 i(9a1t9 jq 7urg2d:unxed 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same consn8a3 26rpx7u nunds9v( 1jnha7td e:, cidqg9 tant braking force, 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 m0jvp)m 2g8 xqdistance on a straight, le8pxj m0)v2gq mvel 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 mass orbits the Sun in an elliptical orbit. Neglectisi)mm,g 3lg3 adg1y4 ung any friction effects,a mu3 ig m3g,lsg41y)d what happens to the 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-energy:qmti;, o.8 a9e5h )jgwatjfh 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 potentia2e r 3 )j08m:gxf/to poomt1hcco1 rr4l 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 second object tijv25 94mb x-6ledk owith four times the mass of the first if released from t5txbedk2o49jl6 v- mihe 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 to the end of a spring causes it to str7q to4bi w,v 1rno3c,letch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring will 3tb, vl1crioownq,47 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 energy of a sys.wi m;7bpp9udtem

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 kinetic energy K, to itserc+ y3x uk ra-/lh(1f potential ener(-ekl r r1cf3uh/ay+ xgy 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 car drivo w zsd;8b*lj2l3 xg/king 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 sliding with equal speeds along(d 13s yhetf8 zlwm(2o a level frictionless surface. They both slide up the same frictionless hill( (d oe2zfmy3swl81 ht. Which 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 ,grk*-f/ ouxr $m_{1}$ 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 mechanical energy for co /ovmg7x xf 7bcmtgf q9x8,*o1nservative forces.vx*q89o x/xmmgo7f7c,b1g tf

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 jana57bi5na3, 6 (gyxr k ;duafriction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the buildirn,x 5j7;ikd3nag aa a5(by6ung?

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 kinetis: fxlcm 58a 8mo4z/ejd/bkq7 c energy. Do not ignore air resistance. How much gravitational potential energy did t/78 oeq4j5zxmm/8c la:d ksfb he 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 and1 y-4.e 9cng.bi ewkf6)berjw loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did ec.y r 9.nb-kfg64eiebwwj)1 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 conservak8emyd32 vcd/ 8yv.wy tion 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 isyy( i3 f1*cwv+ (ygx2shots 7p

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 powee . hczs+xkub2j1ln36 r 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 is not a u se18od. gad wg7im2(xu 4c 0g0ecsz4init 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 timespep 5yu8tu2yse 5ss/1 the work in one-third the time. To do so, su tsy 5epsy18/5upe2 your power output 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 acceler0j8k 2 twi6t3g9q bseration, 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 helk,p sn*vhm:i0 d there. If the object weighs 90 N, mvs,k *np0 :hihow much work 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 od .hiz6w0 o4aup in the air a distance of 1.0 m, at a constant velocitya4oz.6 hoiwd0 of 0.50 m/s. What is the work done 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 cons+md+,z 4ci festant force of 5500 N for a distance of 50.0 m. What z+eid4,c s+ mfis 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 do,6bnsjd1 2la constant force of 5500 N for a distance of 50.0 m. What is bn1,o 2l sjdd6the 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 force of 5500 N for a+8 nad 1z:w ;;dreygau,d/ wjv3a.pka distance of 50.0 m. What is the net work done on t+w8n g. 3vpd :a,;k jaz;wrdyea1ua d/he 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(zdc- ce wxsqm4e r kfs/42,4k 6.0 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 ramg;b*b t( /fuoxp, 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 a11u z hgl jmo;sbn1 dss/ k+5t4uz+9con an icy surface (assume no friction), with a force of 60.ck5 sbg9 alzs+/u1 h1;sz14tudj +mon0 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 in Fu;u t:4ovp1cbg8 xgq /ig. 6-1 shows the force versus the object's position. Find the work done when the object moves fro;xugu4g1qpcov b: t/ 8m 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 in0yw c* pcjg*4t Fig. 6-1 shows the force versus the object's position. 0yc4* tgwcpj* Find the work done when 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 direction of t dyl4xnyh0o8s -8y.; itph u:fhe force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work d:8.ht xs4ypn l;8h0df-iuyo yone 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 force. The grapacxkzyb4**k)c6k x/z t(1vem h in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to (zky6t/zcbk1xm*) av*x4c ek 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 .vz,1:iqw lb6n 5ulvq to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final kinetic energy of the w 6,.v5uz qilv:n q1blcart?

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 mexs a-xtreo to t:8);dnz271 N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the finalexz :etn; r2t txo)-d 1aom7s8 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 5tmmxa:, ;(5nrum1o8sdnrpe2 .0 m/s. How much work is required to stop th8nr( ump ed5tnx,m1r: 2o;amse mass?

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, what dyz)s9 k 3cx9bik*fjx:eeb9o 0istance is requirib y j3:oc990) sxxfe9bk*kezed to stop a car moving at 50 m/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 cocked by exerting a force y 4.:yjiq 5qgl nvtau-t y.5;eof 20 N over a distance of 5.0 c. j:yqt;y-uvyn5l. q45et agim. With what speed 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 +y/5ruyxke8x 80 N and a 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'/ux8e yr x+5yks 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 shot horizontally into a bale of has 5 2j0 atnk2xicfoa.9y, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force asa 9ca5 0.tjki2of n2xcting 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 height2fz .z)q sw(k/zczg( eclh70 h of 7.00 m above a floor to a height of 13.0 m above the floor. What is the chsl2whzq( cz zgfz/c.h(7)ek 0ange 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 pusheb)t4*xq0ooyk 1 k p*ju fpc+0tegh0 6yd up an inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, )qf60k*p4pt0 e o1hxbtyyc +ojk0* gu 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 the spring to stretch 2c)7 ;orjbeupmir;-6 a4mc ,ha.0 cm. What is the sprinm6a)au7;-ho;ccep rm4b irj, g constant?

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 constant of 60 N/m. How much potential a( +)kwshcm-oenergy does it store, when stretcheha+ mows-k( c)d 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 requirq, q01go mfdt;avjs 95ed to compress an initially uncompressed spring with a spring c5sgj a9ov1dm ,q0 tq;fonstant 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 constan9c0q2 lirolg,lq7 ,*rz mayc6r k7b3e t 40 N/m from x = 0.20 m to 0.25 m? (Assume th7qr9mki2ab 0clr * eq7,yz3rl ,g6cloe 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 -nsdzf(bo0 ij+ 4jb6g s m;m8d3.0 cm. How much work is re jmgi+;dnb o84bj z0(sm6 -sfdquired 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 re5,sg+ h24 w5hzzchio9jzddv se891t est from the top of a 50-m high slope. What is the speed of the se9 czh+o 5hw j,24zei91z 8sgddhvt5slier 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 tofj tlb3r /6b(op of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving aftrl o(b/3bj6tfer 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 frictiwxc ll.59w6g: b0hv caonless inclined plane. At the bottom, it has a speeax0lcgwl6: .b5w vh9cd of 9.80 m/s. What is 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 floor. When it is 0 aniclll8d n. )v;l.4m.70 m above the floor, its potential energy exactly4mdna .l;.c 8) nvllli equals its kinetic energy. 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 10 N, blasts straight up from ground gpu:r,a 9 rb xw6 eb6leeof8(e0b3hk6level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what verti66ek3o: bx ablur8h, 6 efp9br(eg ew0cal 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 grgitg4oh3oo( cg+9, yiound with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its laun g9gg4o +,h(cyoit 3oich 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 of a dip dsbr;5 .8,nwo k txn7msuna.uu .m8;m (lhgd((See Fig. 6-2). Neglect friction, what will be the speed ,8 n(.tdr5saougmm wskumb(.dxu;8; 7lnh . nof 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. 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 aancwl)rqi 8tfq17r-7ol(v 0 of 5.0 m/s at a point 45 m above the bottom of 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 bottomi8 qvac0-oqw ll7 )n1f(r7tar of the dip?

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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 star+2rus: ,lksyy1wc :ucts at a point 30 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, w1sku ,w:ysl2+y ru:cc hat 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 t)3 pjipsk vj8,he bottom of its swing (point

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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 cmov5cna; ( d:bj is pulled 30 cm away from the vertical axis and released from rest. What will be its speed at the bottom;ab :cjon5dv ( 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 380v:dbu ihg eat 25 m/s hits an initially uncompressed horizontal spring with spring constant of 3u0v:8 hbi edg$2.0 \times 10^6 \; N/m$. 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 ca4- pb5w v-yh5q;cpdjo r to stop for a red light. What work is done by the friction force ag-d4-qoyhc; pj 55 bvwpainst 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 horiz6h2r*vrfrp dh3 xo 7dt8k/,ui e ;j:sx8du9i vontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to3kip u 8it:u 7rdvrjv8sxdr/9ho h2; d 6,fxe* 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 moving on a ;k1wbso+ ep.*n1z rgmrough, level surface. It has 24 J of kinetic energy. The friction force on it is a cog 1km*z.n wrbp1e; os+nstant 0.50 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 mass on uqzpa/3va5ila il. v 8f3mn25a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is2 a vn ll3p8fa.u/v35mziqia5 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 hix1c* h .zxa ow id,wke(2mej9,c3n-whgh slope. If the work done by friction ish( ,-newxhodx2,e9 a mjk1w cc.wi* z3 $-6.0 \times 10^{3} \; J$, 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 any8m z(rg(y 9py1yo*u-tia/h4ro3 avp d rises 2.0 m. It requires* (vm 4zh8(go39u/p-ai y yyaryt1por 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 aboh3w5vq by sjlh p4f(b0/:t ir:ve horizontal. The coefficient of kinetic friction between the mass and the plane is 0.200s:bvhlj3q/y:bpr4ifh5 (wt . 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 o cdo9sic5cs ;zd ;j)8qf 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction azssdjq;;co 5)d8ic9 ccts 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 energypza+3w*r(gry8iqc t8 when he runs up a flight of stairs 10.0-m hir8rq *wc+gzy38 p(ait gh, 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 bxn7y7 vna(k*8y4l 3 czhtyk/ velocity of 5.0 m/s. Wha 7hxnlvk7 z a/*cn(k 84y3bytyt power must be delivered 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 e54*ixt ll; xtcnergy are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp = tt5l c;il*4xx 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 atwc;vemb)78g g the rate of 500 W while riding. How much force does her foot push with when she is tra 8mgb ;7gvwe)cveling 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 is thh- +enzw:.s ;bo q03vc1og orye average power delivered by the engine? (1 hp = 3 .s ov+n10go- cqyzrwebh;:o746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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1	2	3	4	5	6	7	8	9	10
11	12	13	14	15	16	17	18	19	20
21	22	23	24	25	26	27	28	29	30
31	32	33	34	35	36	37	38	39	40
41	42	43	44	45	46	47	48	49	50
51	52	53	54	55	56	57	58	59	60
61	62	63	64	65	66	67	68	69	70
71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90
91	92	93	94	95

1	2	3	4	5	6	7	8	9	10
11	12	13	14	15	16	17	18	19	20
21	22	23	24	25	26	27	28	29	30
31	32	33	34	35	36	37	38	39	40
41	42	43	44	45	46	47	48	49	50
51	52	53	54	55	56	57	58	59	60
61	62	63	64	65	66	67	68	69	70
71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90
91	92	93	94	95