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

1#

What is the correct unit of wory .p*jz;ao d;y-lh ,ork expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no motio1hyhr8gna7d q: 4k) pr dw09;ccewf l+n?

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, thekot g j*mb1b6q/*9my s amount of work you djb 1mg m*9bk6q* /styoo

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. Ho :bl j73(yl;5j)v2icnm,kuwv,ml jrxtij7d 6w much work is being done inljwv6 7jlktlbv myi;m xr, (jn7uci )j:,d532 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 at a constan-vih)zzxd br8u -/a-x t velocity carrying a 10-N object, the adz-zirv b8 u--ah)/xxmount 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 qp a/o(3p*uj+qdq4k wreturned to its original position. If the total weight is 30 N, how much 4o 3pj q*dupw(a k/qq+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 work on the jt d e5j34dtf.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 wo(ekiks 1-cgm: v03et m/ud9 pkrk done by gravity while the ball goes up with the sign of the work done by gravity wh9u gdet1k kk:/se(-3 0mpvcim ile 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 posi(q lb5jcgqoi5:,3g la;qqx,v tion (F vs. x) graph, represents (3q :vlqia ,oqb5xl,q5cg j;g

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents5e-0bz5: zrdj h+ovk o the work done by the:e+hzb5oozd0kr -vj5 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 thfiox4 cchxal1or lx63;82d3qe 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 is negative, then the object's kinetbt 1,*. nhdhsi:eosp9ic 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 energgc.1enk p(b ,gy

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 kjltcu-: a p:(car, and is moving at twice the speed of the car. Which statement is true about the truck's -c(jl:utk :a pkinetic 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 0j m,2d8l8pok(v tzeiJ has half the mass of car K. The kinetic energy okmt880i (dz2jo pvl ,ef 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 bounces back with half of its original speed. g*xqi;b m*dk,q. y u cked8p66 What is the ratio of the final kinetic energy to the initial kineq.kid6;8mgb,xc py*d *qe ku6 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 spemm t 76z6p5 uhm.t rc;y cz4jw4+kdsm3ed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?t7 mzrwpzsmm6cc6tdkh3j.+44; m5yu

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-yzik,1 z hqf19kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stoppingz9i kzfh1q1 ,y?

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 yo wjk 23 t80)sqd qo*hq9zya8bdy/azm 3ur car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distyazo 2 3tw8qhs9z8d)b yd mqq0*k3j/aance 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 elliptijug )w9f l,a4giy25 aaoxi*x+cal orbit. Neglecting any friction effects, what happens to the planet's+ 4 9fw2i,o)gia*x axaylguj5 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 prq 1ag4 iu dcv0j3ub8.pinciple.

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 poten( 18 k zb d,a(thfn*;lcejmn:wtial 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 dii r,);t7ug5 /1 z6amrrz wwzthe ground. A second object with four times the mass of the first if released from the5 uz zi76, 1rditrr/wa )zwgm; 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 endlevguy);zz69n o-+cjk 0+o9 cijth-d of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring wi jojc6t uzlv+0+ydi-;oge -zk9) h9n cll 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 sysdb.) al:bwc0oj8rly f,.lf;cv t 0f( 3y en.iotem

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 its pote/* sx9vr; 8x; lw1mkjrqa ncc(ntial energy nwv jc*1qc ;larr ; kx/x(9m8sU.

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 drivib9mo :vydokco/:j5 x6ng 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 fsijf29r pg-gj g.+t) very heavy object are sliding with equal speeds along a level frictionless surface. Thegj+ 9.r)g g-fistpfj 2y both slide up the same frictionless hill. 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 ze (lk83* bkm8k,rro t hwi,2f$m_{1}$ 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 energyw 3 8 m3a+sw( xzjedsmyj6am2( for conservative forces. (ew 23d(8a 3jmax6mzmwy ss+j

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 auc si8l -5b /lm(l2rlrpxe q4,lm k)e0 building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potentia4-/l20b (l mkqp)lemx ciu ,rlr 85lsel 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 m0peb + ws1n(fx9ci7znot ignore air resistance. How much gravitational potential energy di0c+ez 9n(xsiwf 1pm7bd the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational potential energyf8,fsyu40 -ik)q ,gxoxoy y- p d-(lwn. Do not ignore air resistance,ls x)04-,nfyy x yu(-odk8 -gqifopw. How much 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 conservation of enesoy os( 6pqsg8gom, 0.zkxl7. rgy.

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 isa8o4voj-u-x)r hk nl8tg61 zb

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 ex1a5+ibdp *j3gp8qrxa pressed 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 is52 y--oba ovt50zha cp 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-third the+,egkt :b 3,e9syla ek time. To do so, your power output must have ,ab see:ge +k9ky3l t,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 chvua eay0k-c hr 3*iy8x4,gs *onstant 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 -(heam orhacmz :o34 q +0w/llthere. If the object weighs 90 N, how mureczwa-h4 +qlmo/al hm: 3o0 (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 o3kg z)4lm d,dyf 1.0 m, at a constant velocity of 0.50 m/s. Whd4 mlg, z3)dykat 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 cs8 -7y3h bbg-,1u 7d ryk.yqemq dhjn-onstant force of 5500 N for a distance of 50.0 m. What is the work done by th-.yduheg3nq-q7 br b -mh71 ,dk8jysy e 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 frmt1uj 0 g)yfor); mi,or a distance of 50.0 m. What is the work done by the weight of the elev) 0 rymm )tf;j1oirug,ator?

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 kpp k0t9(+5c9eu vavg pulled upward with a constant force of 5500 N for a distance of 50.0 pakuv0v99 + k(g5tepc m. What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 pj 9tv 4q msl5g 1f/gte.*u0uhm 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 do eg;o.6lbn msw3d2r t9wn 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 S*fgj :iv0bk/ 9zqexv3 arah in a sled on an icy surface (assume no friction), with a force xb/vk30efj9*gi z:vq 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. Th*y qwe7oc pt5z(:c e4be graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the obzbp4(5w cctqe 7 o*:yeject moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fi2un i8bsy5 v9wg. 6-1 shows the force versus thenu92sivyb85w object's position. 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 iiq ;pq8: felo)p w.r7cn the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. F7eqp8 : qro;l.ifwc)p ind 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 force. The graph inynjc3d yng00ifhf -ik00 3 :kh Fig. 6-1 shows the force versus the object's position. Find the work done when thej0 k33yd -yh c:inhiff0ngk00 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 applieda24 +0bg:iza:jk cxog so97** tszdxe to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final kinetic cots j 9bsxa+axg0eig:z:7 2d z**ok4energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at res 8+q d5h8 )9p:mynqhk2rsr abpt) across a 10 m level surface. What is9dmbqs+ p8:pnr5qr8k2h) hya 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 required to 3t(y. 82kfa:q h7,nqpb6lb:zethna n stop the man7flhh n 3k,b8p tq(: a2:6tzey bn.qass?

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, kuhd0jo n 4:irf4w 08ywhat distance is required to stop a car moving at 50 m/s undroi wh00 4y84ufnk:jder 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 exr5op3 2ls1od1pppc4j erting a force of 20 N over a distance of 5.0 cm. With what speedlrppj od1ps5oc41p2 3 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 and a vertical cop-eyn 2omhr, 6mponent of 60 N. The fore -ry6n,2 phomce is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

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 intid/dlj802avr cl9vnxbb 0udn 5)k q /:o a bale of hay, striking the hay wi90ibnx25l b)d8vvkncu /q0jdd l/a:rth a velocity 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 71az/; j hxf ()kgxkbwumg; 6(l.00 m above a floor to a height of 13.0 m above the floor. What is the a; k/;ml( )wk(ghzu xbfg6xj 1change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4z 29l7 0hnme3lelbt+t.0 m long and rises 2.0 m. If the plazmnl e93e hllb270t+ tne is frictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the sph42 lusxn.f0 :u9mjx nring to stretch 2.0 cm. What is the spring consfxu:4nh 2sx.nl9u0j mtant?

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 potenti-w99ea qc kb337l.jplxsc2 :vjiz-b fal energy do3ll9jis zfe7j9 c3a2: wq--vbbcpx.kes 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 tr cevmz/) +vyu)tcmb(rq8 2h0x1* ocxovq1d3o compress an initially uncompressed spring with a sprv tdm) c( or8 b2o3u/0qxm+v )hx*eyrqc zc11ving 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.n 0sclvi*z, -r7kwfb spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x = 0b-r0.cwnkf 7,vslz i* .)

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 iwjp ky6+n)qe2y--l donitially compressed by 3.0 cm. How much work isyjp -)+ y26wonlkeqd- 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 df hx+mb 0ma03from the top of a 50-m high slope. What is the speed of the slier on reaching the bottom of the slophxm+m30 b0fdae? (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 tbkw5e9wv j)(r he top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fkj)vr w(5e 9wbast 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 inclined plane. At the bots.8 4t2k)jlo;jxuw a otom, it has a speed of 9.80 m/s. What is the vert.84ua ;2xjwtjl)o oskical 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 the5aqd xqme fo *8:z4:v l1nvh6t floor, its potential energy exacxl:vd*e6854 ao tqn:fm hv1zq tly 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 3kp zc2sd fegx5 p.p77 st0l*hfrom ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its t5 7p7klehpz20tfp sx3.dg*scotal 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 thaqdb,5zv.pn*4ji xndc,m 69 j e ground 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 launch point, dzd,.c5d ,mjipv6nb4xjq 9a *n id 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 res,d/zx jdzz8i,*1 zmo 4t.bebdt at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be tz8z , jdmo/bd,*btezdx 4i z1.he 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. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m above the b 9 mssgl;lws4kg4c0l,ottom 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 abovsgclmsw0l4l9;ksg4 ,e 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 39m/xj:t 8iaql0 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will ti8ma/ xjq:9lbe 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 baiq+1ushd d b23ll 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 3n+t +9 vo*h)+he* xx:ft,n-kfhj eiee3uf s* z0 cm away from the vertical axis and released from rest. What will be its speed at the bottom hfhe vxt is9+ne3 *o:-k+uf**nj+e ,tz)fexhof 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 yapxig* q2vc+x 3i/3ou-1 uu2vd0f ba/s hits an initially uncompressed horizontal spring with s v/ic da-y3 30iqa fuvp*xu2go1x+u 2bpring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to stop for z5clkfl- 2ocv tl :y5++h /vhta red light. What work is done by the friction force az - ov+htty5v/f+5 lk:hcl2 lcgainst 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.zacy ,xj0k*- p0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stoz*j,a0 cyp-xkp?

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 rs2fiu:4l sfypn-4z l 3ough, level surface. It has 24 J of kinetic energy. The frictios 4:ifn2-4y lsuzf p3ln 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 applied horizontally to a 2.0-kg madgw.h;.(mnr ;)n oz fyss on a level surface. The coefficient of kinetic friction be;ng zmfd (wory.;n)h .tween the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m higl0.r ield5rc i//*weaih 63lnh slope. If the work done by friction ll d *a06ei/ wr3.lnh5 icire/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 ar c(c+qlyh(-v n 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 planl+(v -yhr(cq ce. 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 d)/),,afwchtws0 m avz ,jj0fplane inclined at 20e above horizontal) 0mfc/,whvjjaz a)s,0 tw,df . 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 strikes t3we,okm . ban4:aj8lfhe ground with a velocity of 7.0.af43mnobaw , ljk:8e 0 m/s. What average force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energybb,4ok rqa1 ,wuvw8t+zj+, wv when he runs up a flight of stairs 10.0-m high, inuw4a q bbkv,o zwrtv+w, +,18j
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 consaeamfrn/vl 3wk f(fp8 d1) f-1tant velocity of 5.0 m/s. What power must be delivered to the object by t 1pafaf(rd n8mke)wlf/3vf- 1he 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*kobjjj - )ka, hp motor that runs for 1.0 hr? (1 hp = 74)*ajojb,k-kj 6 W)

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

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

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

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 5 gzss01)vwne;0 4up8bf) co ry00 W while riding. How much force does her foot push with when she is trs4w oucn)sy0p 18zbgf) e 0;vraveling 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 gtin.j:rmw44 is the average power delivered by the engine? (1 hp = 746 W .jr44img wt:n)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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