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

1#

What is the correct unit of work expresse:swvo) y 9xif1aj2. wqd in SI units?

A.

k g m / s^{2}

B.

k g m^{2} / s

C.

k g m^{2} / s^{2}

D.

k g^{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 mo;gn9hyi-z h (o fil4so)dmb(4tion?

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 haraycq75b0t 6bs d against a stationary brick wall, the amount of work you7b50yt6sb caq 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 muchnl8kij3u b q 1v9grwo7 :;hi(f work is being done in holding the boxf7;u h(1bivqlo j:gr 89k3iwn 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 constant velocity carr.3(0m2vr. ;s h qqp er3*zrxppxw*kcjying a 10-N object, the amount of work you do isr*.2v r wxe 3px3.jc ;r (ppkzqh0mq*s

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 o84 ec di -k 0ot nfme7ay8z.qtx4*w:ririginal position. If the totay 8r:e n0- iko4d ftae*wiq4x.mtcz 87l weight is 30 N, how much work was done?

A.

45 J

B.

90 J

C.

180 J

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the obn)me;b 4mbc /i 6k8djih/,nbgject?

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 dobetjd , l11pbt n,,o3xne by gravity while the ball goes up with the sign of the work done by gravity while it goep,bdto13x1ent,j, bl s 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 pomca ohd 18.vpyvtyip3)xb3vn; v0 t76 sition (F vs. x) graph, representsa6 hmp nbo3ti.0x v7pdy;v3vv)y18tc

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the work done by te0:2eu4q j*kbzj 8b j0yv 08 yh*srlcche force F?hs e4j u80cke vlyj8y00bqc r*j2z :b*

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} m v^{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 d5qj,njjchw 3l82-+ 6dr+tk hrbons;'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 negat nf:m)r )5kcerive, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the objeco f(ex 3mge0psa k*c71t'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*6gzo p7n ywwja+9nvqt8 ge-4b*5c ul, and is moving at twice the speed of the car. Which statement is true 8oa gg l6ew +w79-ubjn*p4cyqn5v tz *about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has haib93d1(lvw neb 3tp9nlf the mass of car K. The kinetic energy of car J, compared to ca l39n3 np9e1iwbtv (dbr 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 wallng bji83x 16pr4.:xhza ymx 3p and bounces back with half of its original speed. What is the ratio of the final kinetic energy to txb6 ryig: n33phpx .1z j8xa4mhe initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving o5lcewc5 57z olvp(- guh8jo* 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'sp- jgzc *(58 5lwel5ucvoooh7 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 is7l k:dep46gibz(p.chwo lg - / moving with speed 4.0 m/s. Both objects encounter the same constant braki g wlcd( l6gb/-p74zhpok e:.ing 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 /iyo7cvke4x ) 03-a xc5pt sknin a panic, and skid a certain distance on a straight, level road. If you had been travelingk3754ia /- ynxk ctscve0p )xo 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. Neglectil*+xyn8yupo2 /)wki e ng any friction effects, what happens tkn/*e )x8yu i2lp+owyo 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 principlee s2lw;.( id-ty0;b) ymsowfs.

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} k x^{2}

is

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential enezx 4fh vky3(r4rgy?

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 hei0 xun86 r0jibi6awg. vght h above the ground. A second object with four times the mass of the first if released from w.r0 6gau 60viixn b8jthe 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 o6 er,m6m cvphp4an)a/ f a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potentimv/)h aepm4 6anrp6,cal energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy ul.+w oa:tqu7op1 -cw;pdpa6(r5 wg.m*ce mzof a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. :voo em8 t4qr(a+u:ik Compare its kinetic energy K, to its potential enerk:eqm8orou v4t a: (+igy 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 driving up a ofw: b(qmf(jnb p c,qbhm.vaa*36b69hill.

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 spee w9,zwf tfc 8ja75q2fods along aofwjt7fqf 58 2a,9wc z level frictionless surface. They 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 )fn90okzl i5u

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 mec ziw:seyl -d9k8tb(4k yhe:1 yddhi3/hanical energy for conservative forces.thed-y(4i d9 /:dh 3wyk1e:i8ybszlk

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, thlm p-lh: ia:72 pmzysxy*q9nyhy4;pf i:k l2(rough the air (air friction is present), to the ground b(p fy mh yl-l y:yz2:l*pkix:s7i9panh;42m qelow. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Ds /v*tw6oas6c o not ignore air resistance. How much gravitational potential energy did th6s/ *wv6tosa ce 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 3m ikb7 43dx-ov0 J of gravitational potential energy. Do not ignore air resistance. How v7m4k-ibdo 3xmuch 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 consx 7po e+6)gws 6z8e7 8ptmbahservation 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 is ux s0as9ss+o7

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 exaq.vcdf3+ lw zehz az;g*+ )c2pressed in SI units?

A.

k g m / s^{2}

B.

k g m^{2} / s^{2}

C.

k g m^{2} / s^{3}

D.

k g^{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 unu s-)2zohg 6s vkez :/42rthddit 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, x 9*l7v7x cbxdyou did 3 times the work in one-third the time. To do so,xl7 v7dcb*9 xx 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 acceleration,3bod*y313 4hniod gre 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 the object weighs 90t1arn: ds//n30u jo nu9er 9w:; xtykh N, how much work was done i9horrtn e swn90jn / a:kx ut1:;y3u/dn 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 distancz ehsn)ciks ,xn y*h 3yoed: k-o3f06;e of 1.0 m, at a constant velocity of 0.50 m/e;0eszsdc x nkf :k36 h-in3yhyoo*,)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 up zn tggg: f-o8.rt2:skward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by thetfs-kg :2: otzr.8g ng 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 up+a+.hc*ec(cnj9dg q x ward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of the c.h *+njx9 ge(ad+cqcelevator?

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 f *:mogh xok80+wc9vbldnx p(r z w.c.;orce of 5500 N for a distance of 50.0 m. What is the net work done on two r cc(nx0z*8.+.okvx plb gm:d;9 hwhe 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 42(ba5uep 5 c/bk nurw6.0 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 slii64gsgbsl2ff*x5 y)t;n ;s))6s 7bx gaycg vbdes 8.0 m down a ramp, inclined at

30^{\circ}

from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A.

157 J

B.

- 157 J + 78.4 J

C.

78.4 J

D.

- 78.4 J

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an cy7pkwqnx:)o 7g qt 73,cp(t bicy surface (assume no friction), with a force of 60.0 N at an anglepng bqt3x):q(co 7p kw c77,yt 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-;s4zzw olvkxm)u 6h 7e graph in Fig. 6-1 shows the forczokw;v-zshx) lm764u e versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A.

20 J

B.

40 J

C.

60 J

D.

80 J

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Tdud*qd m 3(y c2icd v-fs,bs;;he graph in Fig. 6-1 shows the force versus the o;ssfiudbd(m-;c* d,3dq 2ycvbject'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 in the direction of the force. The grap-* f2jo xuo(8hzzq3ysh in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves fro-zf*z3 2o hqs8u(yjxom 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 in Fi-p; c ey:,r iy:1pxm ccj6*05 densrq*g9ws grg. 6-1 shows the force versus the object's position. Find the work done when the object moves fs*6*pr mjrs:yc,in9pgw ;1c: 5 -dqrecey 0gxrom 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 appn j45zb62twd8f ng8ula -;ve8hrof7 k lied to move a 55-kg cart (initially at rest) across a 10fj26k-b v8e hrdlg54n7fun;az wt o88 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 p.(sqkp)9z4fxu8tzl1hl i hmhq 9-s4 N is applied to move a 55-kg cart (initially at rest) across a 10 m level surfs-mp.9ht( ) 9zhf4lkp1hix ql zus4 q8ace. 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 ibv1ktele*3ft7yh *7ex 7rlq4 s required to stop thellek77e*xt 3b ft4rvy* h1eq7 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 initiatzcxn yrflxy7ntf+r*8*a3l .:97cjhlly moving at 25 m/s, what distance is required to stop a cf .f7x3 tlr8y* *tan cz7xh+nj:9cyl rar 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 exerle8sqf:nw6 /4hf7i r o66bsq,v oa2b sting a force of 20 N over a distanceqbl87w6er/ vao, 6 bfh2 s6sn q4:fsio of 5.0 cm. 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 80 a7z2,.0z)scfis -cgctoh.sgzikg1 6 N and a vertical component of 60 N. The force is applied to a box which rests on a level fr7cikz1ogga,g cscsh ).s2. z it06fz-ictionless 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 into a r7fu8x/h26tca vweue c9me4; bale of hay, striking the hay with a vel 4emcfwax69ruhtev7e u;c8/ 2ocity 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 above ag imvlo4b , 0n k,3fi2+d2kwdl floor to a height of 13.0 m above the floor. What is the changelf mk0vbiwl4+ ,o2,23ingdkd in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m lont:o /ce mtdcn+ wo6..ng and rises 2.0 m. If the plane is frictionless, how muchdmno: w/ttc o.e6+nc . 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 cm. cm2 6d9 fq ytm6q(yy7rWhat is the sq6qyry7 mtcy26fd m9( pring 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 6 elr649n1 3jebyx) tcr0 N/m. How much potential energy does it storee t3)9rx4j le1b cny6r, when stretched by 1.0 cm?

A.

3.0 \times 10^{- 3} J

B.

0.30 J

C.

60 J

D.

600 J

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncomqx /x 1yyf*e m,s/xuz;pressed spring with a spring const1xx ye*zm/,;x/fyq us ant 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 conb7 3 6g m4 eo (jepg4+)svuzl/5qparmzstant 40 N/m from x = 0.20m45em4 6jpu)erlz a(obg qzv7+/sg3p m to 0.25 m? (Assume the unstretched position is at x = 0.)

A.

0.45 J

B.

0.80 J

C.

1.3 J

D.

0.050 J

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially jmp7(u)3iwpu-hrl( yl+ u l9x compressed by 3.0 cm. How much work is required to compress the spring an additionawu)purh3l9x +l7i- m(( ujplyl 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 wz 2n*qll1rz q2 3(nzsfrom rest from the top of a 50-m high slope. What is the speed of the skier on reaching the bottom of the slope? (neglect frict2 nqzlr*q3z2n lzw(1s ion)

A. 22 m/s

B. 31 m/s

C. 38 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 offj4;ddzifraxm ; o 5+s4 the top of a hill with an initial speed of 4.0 m/s. Neglecting frictafr5 s+;d4mxzj ;dio4ion, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bottom,aec-,w*+ g:hxajgm w ; it has a speed of 9.80 m/s. What is thm :g+a,*g h;ww -jcexae 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 floor, its psx bcwwrdpj62tzrk 1s/ -iot(-i-8di(b 0 po0otential energy exactly equals its kinetic energy. How fast is it mc8s-dpr sik/zbd o tw0- i0ijr2o(xbt(6wp - 1oving?

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, weighinzigqg jwgwu*3/b q/: bj*gq09g 10 N, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical heigh*g uib/0gqbgzqw wj g9j/q*3 :t 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 7,hjz: u,yvi f .r(fulleaves the 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, did it rise(r,ffu jh7:i uzvl,.y?

A.

\frac{220}{m g} m

B.

\frac{120}{m g} m

C.

\frac{100}{m g} 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 poiz/7ahlifi01(:- y lxm upyj 9unt 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 :mxuly0i (u9 z7y1flpa -/ijhnext 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 atuq4jgyrs +gy rd(2n+v- p-6c p a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the rol 2sqr6 r --v(dyu+ yg4+jnppcgler coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above thei7i06d/ lr 3bbnpak m26 f*odf bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coastmlob/b3dr27ad inif 6k 0fp*6 er 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 sp)hmh- 8cdd 9ri 9fwsl.eed of the 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 2-kg pendulum of length 50 cm is pulled 0.16 mx:5tp ,zh0bcl1;bc pr away from the vertical axis and rbx,th clr:czb;p150 peleased from rest. What will be its speed at the bottom of its swing?

A. 0.2154 m/s

B. 0.574 m/s

C. 0.861 m/s

D. 0.718 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 uncompress 1dxbhn01n msf;t zd69ed horizontal spring with spring const;s916mzbhd xtn 0fdn1ant 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 stop0j.unt w+a0bu for a red light. What work is done bnab+ ju0t.w 0uy the friction force against the wheels?

A.

- 2.2 \times 10^{4} J

B.

- 4.4 \times 10^{4} J

C.

- 4.84 \times 10^{5} J

D.

- 9.68 \times 10^{5} J

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kglu:1: 1 j*9u *:(0aergvotlb du txqxa object and a horizontal surface is 50.0*1 xv:daarul:0*:(q1 tetl g uo j9uxb N. If the initial speed 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, le,p- z ftomf(e+vel surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. Hoez -ffom+p(t,w 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.r3qwz ut94ef (aep9 0o0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface efu3rewzp 9 ot9( qa40is 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 c; u ooo2.wq:gth/y1s-m high slope. If the work done by fw1go.t u2sq:;ch yoo /riction is

- 6.0 \times 10^{3} J

, what is the speed of the skier on reaching the bottom of the slope?

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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 pushedkk1,zsus2 :we up an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of workz:1, e wu2sksk 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 r0ko)z e1zivq yy bk-14est at the top of a plane inclined at 20e above horizontal. The coefficient of kinetik1yk4 z1 -o)0i zvqbeyc 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 the ground with aq-c4ueev ,a t: velocity of 7.00 meatu4ev : q,c-/s. What average force of air friction acts on it as it falls?

A.

22.5 N

B.

75.0 N

C.

225 N

D.

293 N

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs (qseyt62arg 2d0 .ejpup a flight of stairs 10.0-m high, inye(q02edr jt62g.sap
8.00 s?

A.

75.0 W

B.

735 W

C.

4.80 k W

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 lpaz ehsjtvg t6( 1j)k4 v3,7hto move an object with a constant velocity of 5.0 m/s. What power must be delivered to the object by thjtze)jkalh (th 3gs ,pvv7146e force?

A.

0.50 W

B.

1.0 W

C.

50 W

D.

100 W

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp j:k akiv;3x8m2figkg4ip-r d88kkuh--g g 9 kmotor that runs for 1.0 hr? (1 hp = 2d-gk x3jkh8:mivkf -k9 rkg;g4 8-iap8uk ig746 W)

A.

3.6 \times 10^{3} J

B.

2.7 \times 10^{6} J

C.

4.5 \times 10^{4} J

D.

4.8 J

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W8 dsl7r.qw 5k++ nu(mygkqmz3 while riding. How much force does her footqgsz3lm.u+ w(d mr+kk85qn y7 push with when she is traveling at 8.0 m/s?

A.

31 N

B.

63 N

C.

80 N

D.

4000 N

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is the average po ,ce7em6gw0n us ia+9iwer del7e6en+ u 0s9iaw,cg miivered by the engine? (1 hp = 746 W)

A.

60 h p

B.

70 h p

C.

80 h p

D.

90 h p

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