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

1#

What is the correct unit of work expressed in SI units?mj r0m s4ars:,

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 systfn(tm9wql a:hz a5n j(;qx 8:nem if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wa s:):d tf+.d rjhrrx-+:eip uwll, the amount of work youswi:+h ). jx: :+defurtrrdp- 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 liftedx5td; pj( jdj (s(*oh h;opncva .6h0n 2.0 m vertically and is being held there. How much work is being done in holding the box in thj.p(6(5a0jc;s jvh ohd(d;oxp*t nnh is 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 forwardkd)jh b n gl;drd/2)2gj3gm a zifm-39 at a constant velocity carrying a 10-N object, the amoj d3gk r -h b;3lg2a)nd9dmjimgfz/)2unt 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 liz3k)h ez2 lp3jxa/w1gfted vertically 3.0 m then returned to its original position. If the total weight is 30 zjz1a ehxkl /33p2w)gN, 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 they ;dos/r0 h8hm 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 , p tagc .cygp35zb1k/while the ball goes up with the sign of the work dypk ,t3a5/ccbgg1 .p zone 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 Force versus position (F vs. 8mhj+ 4; dad 8rn)2hbm,9yhot zcvit: x) graph, representsi,m y4:+ h;r2 8dtzd8 hh)mcjb9tnvoa

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 puxj9yt+rwk8dgu n+ 7+ 9x a-cqosition (F vs. x), what represents the work done by the ua++ 9- cg+k8xy trn7uqd9wjxforce 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 posi8 jqyai 2oq2s(qw1s2 jtive, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then the orme71t 3nvq9d bject'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, thehgkif 9 yaa23)n 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 mtgs94 i n40zoguch as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to g94z0sn4itgo 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 hczq.vyha dhvn (s61 7 c-zx d/ig3h(4walf the mass of car K. The kinetic energy of car J,(g q.c-hc(4 hz16vny d7ihwdz /sva3x 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 annc1b5srw/) 2vk dvor9d bounces back with half of its original speed. What is thrsndo 5 vv9)b/r2wk 1ce ratio of the final kinetic energy to the 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 mo; 3yo;nojke/a)if:9 0m nkqwrx8 k6bjving at a speed of 5 m/s. If both objects have the same kinetic energy, what is6 yx8k)9 ;j mfnrkwa3q/ji;:k noo0eb the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is movinzqb g)qq.,m 2dh u38srg with speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant br,gubs.qq 2 d3m )hzqr8aking 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 cak7*ylps y1jx 4r in a panic, and skid a certain distance on a straight, level road. If you 1*j7y pkyslx 4had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits th2ycs h9esve 22e Sun in an elliptical orbit. Neglecting any friction effects, s22eh9e2v sycwhat happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy prix icu,:kyd: 6td)cc2x nciple.

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 syste*rnu/ufq:m g )v0a fu:m to have 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 ascgey / wu.1r; l6k8fq(qru g*bove the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second object compared to the first wqfy*sqgk8c ulr/6r.e gu (1;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 causk:aqj pn)kzrbq 0;-i9)oy)i .(grornes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of they br; g jr.q)qa)) :okinknp9 z-or(i0 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 enf1k. 5zpkq 4taergy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. j1o2mvhogz,z1y )z x*Compare its kinetic energy K, to its potential energy 2g1hy zz)mv1o*, oxj zU.

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 vy4,x:lco /h ,saa0.yb ea2rg car 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 psavae+1n4. e heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionlesp.se a+41 vaens 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 (1qs9xktbzn l f9q 0k2$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical energy for conservative fmv fhm,g g. wj;2p-/x*)qmfjjorces.p;x h mfjjm)f qmj*,w/-.g2vg

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, through the air (air friction gaw;+ ds j2,mm +y8nstis present), to the groun, wnd2y+;8m sam sjt+gd below. 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 ebz/0ulnx +: okpux72osvtp67nergy. Do not ignore air resistance. How much gravitational potential energy did the ball losk/ut uoxx2bnp0so 6 lv+7:7pze?

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 m,m.+o ejlxz/of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did jm.+oexm,l/zthe 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 exy2o/ive 7qg) nergy.

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 ist n1 q3cj(25lbc ygk+p

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 in S.n,m :rz (7)lxys qjce8 *bc2su -mwlkI units?

A. $kg m/s^2$

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

C. $kg m^{2}/s^3$

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit of po lqiju 13l6mdts/ xl +5e70oa8a;p axewer?

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, yb) l vwq4*ftzfv:jb:vi)7qi/ou did 3 times the work in one-third the time. To do so, your power output must havtvvzfq*: ):bfv)wilq/ 74b ije been

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, the car's enn+ :vu.e)uf3oae+i it gine 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 a -x (w:qe 5u.ggw.cawpnd held there. If the object weighs 90 N, how much work wa-:c u.5p.wag(e xwwqgs 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 ytxwi (x2m8(oi4 ad.b9d*zvy the air a distance of 1.0 m, at a constant velocity of 0.50miaz xi8bwt(2do* (xy9yd.v4 m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant forc1 bvzyzbt0 ke y*q; z/ug54rd3e of 5500 N for a distance of 50.0 m. What is the work done by the 5500 N force5ybz 1tzqvdz/0 * uk3r4yb;ge?

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 pulledwiek c.;acpth0032u 2sqy8j t cq12fr upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of the e;twk1q8s200h a t i 2q c3e.pcryucjf2levator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500e vxz:7lel* u. u*k7vm N for a distance of 50.0 m. What is thelx*:7 uml7ekv.e z*uv 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 0flhax0l; 5d 4pms;ld 6.0 m up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m ywkvir9,hm 1(fep( z/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 siste;t6)seh) gejgr Sarah in a sled on an icy surface (assume no friction), with a force of 60.0 N at gsehe )g)tj;6 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 F mig epwa :5b:fxu-/. yudx,6q23fsdfig. 6-1 sh,i 2pbx-efq5gux m6/da s uf.::3wydfows the 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 obje+ am7pte)u1mou;olngp6e g,0ct in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the wor)l1m,ueg+o6 ;agotpue 7pn0 mk 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 ,(efci5wnhr,hvy (p u)l ud28in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves frun )w5((,vfchy ei2 8ldhu,pr om 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 inm t7 l9t1a99ikl mq.y1)ic 2tu avur0s Fig. 6-1 shows the force.uqlritv2 90i 1 ct m)kyaas9u7l9t m1 versus the object's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (ins )oaycqrka +(+ r8fx)cus; n*itially at rest) across a 10 m level surface. What is theqf)ck+oac);n8s r( r*+yxs au 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 2m.a r+ c s(x67 j2v1ah8bsobna00 N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface. What is bx sarm +cj1762(aanv.hb o8 sthe 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 movin;ho*z 3xlpcn1 g with a speed of 5.0 m/s. How much work is required to stop1cx h*zl;n 3op the mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, whb7ch a65z1pgo-lkd lqax5(. hat distance is required to stop a caq6gahb dh-17x 5(laol5 zk.pc r 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 gue 3 8 gjut6+iguwa/w6nn propels a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuminua g+uwitw6683nje /gg 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 aey-6dw:le5)o*a m,)+ fhzq i)qgyaj w vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontall+f:idegqwh *)ae l zamywy),)q -65joy 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 bale of hay, striking the s yh3ul: (kjz:hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stoppin:uyj(z 3:lks hg 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 a flooa8a4v :f.uz ek n;0rjmv/,in or to a height of 13.0a 4jzkm 80rno ;fnae i:,/v.vu m above the floor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m :3x 9bwfutyg5w4h ,gtlong and rises 2.0 m. If the plane is friwgtb5wh yf3g9 4t ,x:uctionless, 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 tl; exia5:xswagmg 5* 1;*ncwco stretch 2.0 cm. What is the spr;1 5w;:wcea* *gg xm5acsnixling 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/g8om;xf e9g g g13j8vfrk z1r spring constant of 60 N/m. How much potential energy does it store, when stez 3 rx v/kfg ;f9jg8ro18gmg1retched by 1.0 cm?

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed sprin:p hxfb8za37 kg with a spring constant of 25 N/m zk8f3axb hp7: 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 stmv knx (hpyq,,c:v9.s retch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the umn:vspc(9xy,hk . qv, nstretched 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 oa /jm)ed2xs:8znor37i d lk3pf 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an addition:oxl/2m sz dd )3nrp8a7j eik3al 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 m-uq24x cd h ir5uv8n;a 50-m high slope. What is the speed of the slier on reaching the bottomu8nmd-cquv 2h5;4 ix r of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial speed of0,9sn /j nbuku 4.0 m/s. Neglecting friction, how fast will she be moving after drnbsj0k u,n/u 9opping 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, 9f8 e12 qrrl+vhk, dngit has a speed of 9.8h91 8krf2nl d,q gr+ve0 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 abzes /.5wy1p icove the floor, its potential energy exactly equals its kinetic isze .1 p5/ywcenergy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground level wou-5v3r n4 g kadtry6mw0;c7x ith a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical heightdgr - n5cukwo;x6r a3y70tmv4 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 wi* qq,n:ey 52e8p*byldvp a1hl th a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what verticapy2eq* 8*qp:d1v b e,l 5ylahnl height, relative to its launch point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the bottom of a dip (q 01skj lit:0aSee Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next sl:0ik1 at jlq0sope, 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 h s:*2d/j/ sy+yzozc ia 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 tjdz/ssyo /hcy+2z *:ihe 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 poink9t/ l x-b/l s;erxzm8t 30 m above the 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 coaster at the top of the next slope, which is 45 m above the botttkrs;9/ lbx lx8e-/m zom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball atee pj)djnb prne0 9c6;h;d(t, 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 cu2 snrf/h37/ b9p w*namz /sgcm away from the vertical axis and released from rest. What will be its speed at tc w/ gb9/r72ssmh/ *pun zanf3he bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an ina3.vq gx)pq ) fjg9 l25y i,l-fgftcj9itially uncompressed horizontal spring with spring constant of c9qf) x 3 2qfg g)l-atljfijvpg.5,y9$2.0 \times 10^6 \; N/m$. 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 obgp q:oda4hi4 ,) q.4c)se raa red light. What work is done by the friction force against )cs4bo ep)q4qgdi .aah:o4, rthe 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 surfach+ 6yretjfo:-uhrot c5n x15* e is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to c+ x5ruo jy hof5-6rht*1:tena 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, level surface. It has 24 J of kispi.l.xo b 8w3netic energy. The friction force on it is a constan wl3i8sb pox..t 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level st+hn e8:i,epxurface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its ki8nx i:pe,et+h netic 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 tob/he* 1srbfx ,p of a 50-m high slope. If the work done by fricbf1 s /rbxhe,*tion is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane n (ki.,by+gko v(w 7yvis 4.0 m long and rises 2.0 m. It rv+k ni (bvy ,ok(g7y.wequires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from res.j5 e 44tj3o qf4upbo8zm (gbzt at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction betjg q zu b4to53fmj.4p84b(ezoween 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 str whg)iv;yfv 2y9la( ,ri1+tmc ikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it as it falls? iymh9)rav,cwg21l ;f it+v(y

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 -i ue ak g(*4xtk-(cuhflight of stairs 10.0-m high,t g(kh( euu-i*-kxa4 c in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an -6s c:s/rvfftobject with a constant velocity of 5.0 m/s. What prf-vc6/s t fs:ower must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used b/3 l- efgq(zi7*mrgkwg jm-3ny a 1.0 hp motor that runs for 1.0 hr? (1 hp = 746 W)w/-mfmgq 3ke7gzr* i 3-jlgn(

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 5007j(qa 2x: ei5+j5) jgjscjfnq W while riding. How much force does her foot ifeq g j +jsq(57jcnja jx:5)2push 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 accelerat sfrr/+7hmim8xsk 0 9wes from 0 to 25 m/s in 7.0 s. What is the average power deli+w0ms hs9 xfi r/kmr78vered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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