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

1#

What is the correct unit of work evt :ps3qu2 mr:xpressed 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 f p0ck.aady,evz*0p7k rnq 8;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 againstnnwa,p0t-, y-4boqrk a stationary brick wall, the amount of work you y0t-bqw,p -nank4ro ,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 being held there. How n:1-/8r *k.k l2kt uzscy ouxdmuch work is being done-.*uso1 u2rdkl k zcnkty 8/x: 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 for8*ogg47 der;c/m cgw mward at a constant velocity carrying a 10-N objer gm;w 4*e7gdm/cg8co ct, 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 returned to its ori;gygsq*6js tkjk7 7z8ginal positggjj 6k*q z 87s7k;sytion. 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 fohzjf m em, d3mqj3ts88q:o6-krce 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. Compare the sign of the work done by gravity whidkxhev,87f4 o le the ballod fhe,v4xk78 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, on a Forcej2o 96ir vb2r5 uivb5d versus position (F vs. x) graph, representsbv bv2rj9r6du o5i2 i5

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 positk5-8omw3ddm2t*5mc *tvodnskh, o c vw)9(ceion (F vs. x), what represents the work done by t8cc *9 ,wmnt5ocvw-s oehmd2ko(5d 3)vkm *d the 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 object's kinet ljl2 gyu7fn+i -x79zlj rrc.3u-z 3fqic 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 ojy9t.:f h)x e)soax* xbject is 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 ta., zwan9kp9on an 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 movv/ax-3scs udi(/:ew2 uir )aa ing at twice the speed of the car. Which statement is true about the truck's kinetic energy compared tosca) -ai is2d/ uw: xuar3(v/e 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 fat yl:ot z--p6iu sx;q8ct3am0st as car K, and car J has half the mass of car K. The kinetic energy of car J, co63mt 8u p0x;al -tyozc :qi-stmpared 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 bounces back withcmyc8 + :kj-vo rogy 3vhe(n*06g wf2x half of its original speed. What is the ratio of the final kinetic energy to the initial kineticomvog-(e0g6 v3 *fynwc+cxhkr82 : yj 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 cjb g 0+wi tn*5nshl9b j1i0t+moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of ttwjc *+l0g1 hbis 0j9t n5nbi+he 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 moving with s kj :b(led f4.scglt,,peed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object tracglbf,k,e: t( .l4js dvels 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 o6gsa5z;prk;oi.d x6;zkqk 5bbdc 3:u f 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 cars;6 5okzbzdxrbk 5g ; k.qidca3p6:u; 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 elli9p9g evtzyzq,+k(b5w6a : n ziptical orbit. Neglecting any friction effects, what happens to the pz 5kgnqv+a 9 9ytzzb,e6 pi(:wlanet'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 principlemva wcg9r4,8on w/uq-.

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 haveq*sx;8 *d rs cj :u63w4kbknfl negative 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 groumqmg u 86ndlues0.02 jnd. A second object with four times the mass of the first if released from the same height. The potential energy of the seconu0nme2jg8s d0. mql6 ud 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 stretch + :buse9.cwplf s4u9b 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy o.sc s4pfu9 +ewbu9l:bf 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 energy of a systexrok*s*pdx:u 0vpkh f2g:q4l-3( wj ym

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, t5 ;jfesvevm10hvzc*wptj hbv21s29)o its potential energywepvf0e) 1j2*2 5tbs91m hvh;v zsjcv 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 gkvv/wi(6khfp-s3j.b hl: (q 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 sliding with equal speeds alo ;2 (s8slswroj)8if ydng a level frictionless surface. They both slide up the same frictionless hill. Which rids(ofy)jw 2ss8r;l 8ises 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 a: g(u/d9ycf1(arus j,k r)ct$m_{1}$ 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 ofw -b i5uk,stv7 conservation of mechanical energy for conservative forces.t 7 vi5,wbu-ks

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 to 3pcqf t1/:rwhe air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground comparr tow:/p1c3fq e 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 energy. Do nl2b,hs8cn;cdf c uo/ -ot ignore air resistance. How much gravitational potential enec,lcof h /b -8c;2dnsurgy 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 dista 6e;z,uxo0jww (ghd3g nce and loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gai d6z(w ,u;0ox3jgewghn?

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 or:w:zxzl: 5so9ivlwjja5e0 x(h8g u- f 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 is a5c *; ceapfdaen h bw++3z-)ai:c+ll

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+ea6hszp n: z5n 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, wh.;+r w9 ld8v6xcj;yfca w,zbbich is 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 work in one-eymt);8q+ wr e0p,f f4unsfp4third the time. To do so, your power output must have been4f r8wyf0;s4e +tmfppu,ne)q

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 cbixfv 47 r-ca-fk/ w(sar at a constant 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 there. If th-md2l/ lapvrn 2 f4w/qe object weighs 90 N, how mur/lm/qd- a2f ln4w2pv ch 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 up in the air a distance ofw1i 7+cs(ix1l 4jyfw4bw m0pi 1.0 m, at a constant velocity of 0.50 m/s. What iwwj10+i( 41 fs7xylbi4ic wpms 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 w-.1fho a,*z/qq4iez2x w - xlaopdt*lg-d s)nith a constant force of 5500 N for a distancw-qx4fna odtz/zeq2)d* * -ax-gsl io p,lh.1e of 50.0 m. What 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 of 5500 N for a distanba2rjfa8bdtx 6m : (4kce of 50.0 m. What is the work done by the weight of tht2:bf4 r kjd8( abamx6e 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 upw6, 4+i29aaarro. x rwudcne5 oard with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the elevarw+2 arcxd4io6,r5n .e 9uoaator?

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 a7lw (+xjyn;hw long 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, inua6 rz wjq59l5clined 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 sis)) r gpls(6wvzd1ppt5lz*l/ mh;)nvk ter Sarah in a sled on an icy surface (assume no friction), with a force of 60;nd ) )(p5hrvtgslm/w)zl zk1 vp p6*l.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 in Figh.5qe 5tp( kxl. 6-1 shows th ep5kh.q(t5l xe force 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 yqw3: ,o8zyqx the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done wy ,3xqqyz8ow :hen 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 the force. The graph in Fig. 6-1dp)ya j17fqo /11sks w shows the force versus the object's position. Find the work done when the object moves from 4.0 to 6.7wdp 11kaos s/qfy1)j0 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 d4:+0b yclmvk.1 mejwwirection of the force. The graph in Fig. 6-1 shows the force verskc.yjwe0m+b w l1m: 4vus 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 moej )8eo tgs+bkyv:v+ 2ve a 55-kg cart (initially at rest) acrov8v:s 2o )j+ kyeb+tgess 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 a 55-kg cart (initially ati*95egryr,o eb.uavwb o(k0,fp:, wz rest) across a 10 0krygfaw( ui.,o5 ,9*z,vrwbb p eeo:m level surface. What is 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 much work is qjx* k*vt8n.bszw/o0 required to stop th0wk**/ sqzjxvt nob .8e 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/x osqn2(;v0lv s, what distance is required to stop a car moving at 50 m/s underv2xq( sol;n0v 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 cockedu/v bs,zxv *1n so/uf9 by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, 1//nv9sfo xzuvs,u*b 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 and a vertical component of 6n8 l;qg 2i +2djn:qimwpw*4 ey0 N. The force is applied to a box which rests on a level frictionless floor. The cart stare:2gnpw iwdmyn il8j*2+q q4;ts from rest, 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 shot horizm4wv.rk fhrg rmgs/31h 6u5i3ontally into a bale of hay, striking the hay with a velocit mgfr6v 3r h /15.gwhkr3i4umsy 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 of 7.00 m abbqsoctr , o n7 auhw9;r6-b0c8ove a floor to a height of 13.0 m above the floor. What is the change b n c7qh6ruws-t9 ,brc;0ooa8in 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 phm5/zm )nbaa*wq * k(llane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictwl 5b/qkhamz* ( n*ma)ionless, 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 2.0 1wq-dn9o6h fefty4/m cm. What is the spring e n4 fy odh/fm9wt61q-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 2zo; k3xtli,s w)ts yr 4ph:(7s/pvdqt6m g;vmuch potential energy dop:gywt(olh7,; v 4xsqdir)/ztmtvsp2 6 3k ;ses it 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/tf.n7:qfm*g on:c(sf:q vy l compress an initially uncompressed spring with a spring constant of 25 N/m by*fsyfl /( 7qo:tnv:.mcnf:qg 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 from x = 0on+ 2hfc oc/7b.20 m to 0.25 m? (Assume the unstrcf +c obo7h2n/etched 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 ininv(tx9ft5k e -;bq z9yohn* -ntially compressed by 3.0 cm. How much work is required to compress the spring fh(k9 e-nqnbxz9ot ;-t vy 5*nan 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 hi hppx6s qcm4)(gh slope. What is the speed of the slier on ) hpq(c xm6sp4reaching 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 wvx2d iu ds/-+r8)cckm, tyu;hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will shc28uk+cu; dywmrs/ -tix) d ,ve 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 frictionle2)nfmml( ,d or+-o ndhss inclined plane. At the bottom, it has a speed of )-lf n+mn, ddoo h(rm29.80 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 0.70 m above the flosde,0euuc 27ior, its potential energy exactly equals its kinetic e2,eis0udu c7e nergy. 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 )rw jq+g1q.2gd3wwzp N, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical enerqrpgzwgjd.+q23) w w1 gy 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 of5o9 lpbmrd+g3o3pew p3qis- 5ae ,r1x 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative topmo3,s 35aie g+r q-9 pd3exlrbo5w1p 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 start9cjhsjq 7dpdsai ( -8l;).rn hs from rest 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 bottom of the .j)s(dar-hj 9hncl8di7pqs ;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 (wmeor8h0o l arv:/g.a speed 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 thvmor8./ w0 o rh(gl:aee 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 with a spzh4f q1mf9m(l k khj,;eed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the rollefl 9mzqj(fk h 4,hk;m1r 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 tpxyuqtbl +/y3toi.jw /qn-u; bn4)r (he ball at the 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 cm is pulled 30 cm away from thece2j0ok x ui qw(o15xp/frqu26 e1g,p vertical axis and released from rest. What will be its speed at the bottom of its swin(0q2p2j q f5x,ucpu 1or/ewo1iegkx6g?

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 uncompressegu( wounreq*yl3 o8 co:-4u3h d horizontal spring with spring -gon8wo 3ru*u oq4 uy(:ec3hlconstant 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 forl5j bu*grtth6g x16x7 a red light. What work is done by the friction force againu761 g 6glhbt5j*xtx rst 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 r aavuubl.x/6;a)0 xf/xrh;v ft8;blsurface is 50.0 N. If the initial s;. r;uvhba xfft/r/;u 6baa)vlxl0x 8peed of the object 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 moving on a rough, le5g hpf3on,)nt :l0 rcpvel surface. It has 24 J of kinetic energy. Therf ,:n0)5tl pohgc 3pn friction force on it is a constant 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 appli;lhe4)ceam 2y8;oaefed horizontally to 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 move oae4m;)e y ecf;al2h8d 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 52 4swgmb)v n1ystelv:c7b3) i0-m high slope. If the work done by frict yb:nl3wvv)) cet2b s4 m7i1sgion 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 )u;im7/212cd eq tpbul-k mnj up an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane.i2 uuce) l/- d2;1n7bj mkmptq 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 hh; yiua9vbzx2xta7 xr6c (;*above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after slidin;chb ar92v(x aiuhzxy t*7x;6 g 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 ojydcsc+t**a) f 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of ajdst+ c)ya **cir 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 stairzddn-k *k5q8/ u4qib i8cidy, s 10.0-m kyikb-iqd*8/8 zdc5 ,n udiq4high, 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 t y. gt2nyb/7tco move an object with a constant velocity of 5.0 m/s. What power must bg7t2 bny/ty c.e 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 energy are used es mvk) ac,wt3k9)epu,ews g+hk8,e7by a 1.0 hp motor that runs for 1.0 hr? (1 hpkmsh wu8e),k)ec 7p+ eka 9ve w,st3,g = 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 tcz3dh6zb0) u rhe rate of 500 W while riding. How much force does her foot push with when she is traveling at 8.0 m/d 0)zc36rzbu hs?

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 to6g**zd3a adu(b/cr eb 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 hp * raeu3d g (c/zdb6ab*= 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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