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

1#

What is the correct unit of work expressed i5-ul ky1wn4d wh40xb tn 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 uw*zrvx1-e b/3yjq z,there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, t-a9e dtwmb43elg-bj, he amount of work youb9b,tgwjm a3 -e-de4l 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 muchvzy;d5 7ih k nc0;gl*l work is being done in holding the box in this positio5;kczh *vly i7;ldgn0n?

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 verq5ny3db c87 slocity carrying a 10-N objectb 8qdr7ync3s 5, the amount of work you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then1;kupm a1:/ s6qx4y l(jcy gxv returned to its original position. If the total xl1/ a;q j( x y4mpc16vkygs:uweight 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 fu9 t y,3zwf:jkaix23morce acting on an object do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straightq;li 7/y jyyttzx1: 7a up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it go;q17yxt/ltj ya7 : yizes 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 fe nnr:k8;utg7wc/d 9(F vs. x) graph, represents rtn:8cw9eu; fg nkd7/

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 represengwd6p,g9g k. tts the work done by the force F.6 t dgpwgg9,k?

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 t4.r12zyo q9v:luqlp 6 4yqejobject is positive, 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 c*6 4p h9f6vc03w f/ldjgopkb an object is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object isj,kjh6a7ey *h zero, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twice the speed bp1jw*u awhhz4buls ;v7*02 8uebqg; of the care7huzbh 10q4au; 8; wwb* g* s2ubvpjl. Which statement is true about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as9lk bqeh. 0z5g v +rw8k5q9wyw car K, and car J has half the mass of car K. The k 595 vh0webrk.9zqwgy +qwlk8inetic energy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and3/ b.wg ap2t/c/ym sxa bounces back with half of its original speed. What is the ratio of the final kinetic ene .bp/st3ygc /a/axmw 2rgy 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 m vni( a2 - jyt)2mcsuc-+y-vq3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what usmctc- vim2(+nq-2-yva) j y is 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 moving with speed 2.0 m/s. A 1.0-kg mass imx-8) qjy6wtx:bqt * x9xlg4j5 d;f qss 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 l8*q-jd6tg59jxtx bqf:wqsy)xx4m; 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 brakess dxip fm70l a45ftu((b jw2,m of your car in a panic, and skid a certain distance on a straight, level road. If you had been trf( m5w di,l4f2(m 0utxbpjsa 7aveling 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. Neglecting zsa/s*l a64co +hauza;k ar5 +any friction effects, what happens to the pl6r5* us4+skac;lz aao+ah/az anet'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 pr8zr 5y6/c8,uvv a c1j7k vsspwinciple.

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 pote:3wmxgte( y6 j)ze5aential 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 :pu e-g9fofa ux eg9+;rest a height h above 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 fp efo g;a9 eg:f-u9xu+irst is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it 73g2-r0 ima8 *ytfnk vb)lhty5 m0bjoto stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential hl2kvi50* to yrf 7bn3)0ab 8gm-t mjyenergy 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 of a sysdtg2ypdcdc:r9 3 5t-ltem

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 bg86mz x2a) ,koub;hx tree. Compare its kinetic energy K, to its potential energy Ugu x2bh)8 ,zmkba6x;o.

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 ca3 043ft(zus bb9t+ qwg qgs)yd8)vdkar 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 objectrz,dm;4h+0kuv0/ ,d th ss2qt+cgb cg and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up t/;hcb ggcqtr,u dhs2+ks , 04vtdm+z0he 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 :: zyyp4. hslj ps(uh/$m_{1}$ 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 conservativqii2 qyvs2p: g(jjw(6 e forces.ijwyj:sp6qg(vi q ( 22

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 frlfw y7rcmwd .j k/63;qiction is present), to the ground below. How does the kinetic energy (K) just before strikrj7q.6w fyk3cdm l/;wing 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 disk , 87yol94opel t8megtance and gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential eno l ketm48g,pl e9y7o8ergy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J oi7spp96x/ m y41:blbur;(m ptfc6d :wnorq8 ff gravitational potential energy. Do not ignore air resistance. How much kinetic energy did rspx;rfypo(p :b fbw964mun 6i18q/ :t cdl 7mthe 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 ener8nhsjfcon2ld j ).-9zgy.

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 is85c j7xrz. b fl qy8nqr5a+3yt

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 unitytu2cpxx -hmkk 7vmi(r2 -g. 7 2wpbc- of power expressed in SI units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, whipc) pdky ,2-(g n7gokdm,j.yich is not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-thir;pxw3hj96 h * nrr l f*;lpl-zbcqn-j(d the time. To do so, your power zpn9j h3l-xj*;c qf*lw6b(ph r l;-nroutput 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 caldefd8-biv 9sp18:cd4+isc vhkw 70 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 fql6 54njsm(jes y1,uheld there. If the object weighs 90 N, how y4f56m1, nuljss(jqe much work was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distancuu m7llk6.2 5not hl0ce of 1.0 m, at a constant vel.ut h0lc6l olu 2n7m5kocity of 0.50 m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled dcz/gzox6p + .z.2nbhupward with a constant force of 5500 N for a distance of 50.0 m. What i .6/cgdxb.z z+ op2znhs the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N foh vqfgb6n 76 lli,js.5r a distance of 50.0 m. What is the work .fb6sg l7ivlq, n5j6hdone by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 Nt2avca-gz3,2bqv6 t y for a distance of 50.2a,3-vcy ztt2vbq6 ga 0 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 vl,uy8 m)pt* 9ddov,o6.0 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 8.0xvzhwk;)lt8dg(3 azc6rgn :: 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 b);yrhjrd .n98id d1q an icy surface (assume no friction), with a force of 60.id jr8qd)n hb;1d 9r.y0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph 2om. o + 4tcu(modzky)m9lr0w in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 2.0 m.wzo42ytmmcu.)m0(+9d oolk r

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 3;,b/wnt ae ,u )hmemuin Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves fro /)ea u,wmb nehu,t3m;m 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 t1n-oj3y s4qckhe force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the obnocq 1-4 3jyksject 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 j7j52si-anr y direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work donyajs 5-7r2ni je 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 ct8oluzy 3xcpga0 :2(iw kgy*6art (initially at rest) across a 10 m leve ao wz*ly:g8uc2yx3gp60 kt( il 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 )x,ggc6 xchm 3N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final speed of the x6c),cxh 3mggcart?

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 li9enj8k*0ud 3c t zk+much work is required to stop the mass3 zdi 80t9knj*+ kulce?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance i,pl ((frwpc5rzw,r 0w s required to stop a car moving at 50 m/s under the same condition?pc0w(w,r5fp wlrz (,r

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 dar wqk *1ec6xp6bt. 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, assumi qkb16p6*xwce ng 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 verti2i 26d1+f(kg2gb;hpa 4zk k3q yj iveocal component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's fin+pzyvhi4bo;kf3jed2 1q k2(g2a g6kial 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 bale4e,vd8(put* wio em)v of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm m*u(pvde8)i,o v 4t webefore 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 -inn n vrd5q mz06kyx 6)4(rarabove a floor to a height of 13.0 m above the floor. What is the change in gravitational potentr- (vqnn66xy kz irr nad05m)4ial 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 planc,td6-fvf m ,ue. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was donm ,tf d-6u,cfve 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 sprinzm:ha( xc:kqx o3h d0 0nw/oj;g to stretch 2.0 cm. What is the spring consc0( w3daxzmx o h0ok;:j n/qh:tant?

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 poten s2:xd m-0o otlg*lx6etial energy does it store, wheneo6 0 lmt:dxg-sx2 o*l 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 uncompressed sp7iif nif8b3ngubcc34 (s : m0iring with a sp (bbuins:fm33fc8 0ignic 47i ring 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 1gqd hzcrm3 v 10rxl;ewo;s*6of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched p ;q 013erro*hs1vl; z d6cmgxwosition 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 l6bij:sas vn8e/w4 -w 9pvb94dyqr;d compressed by 3.0 cm. How much work is required 8n -w6b9is/9v4 dqsv:w jeyadp;4brlto 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 from the top of 6-e j,ca3wn xla 50-m high slope. What is the speed xjl-wa3n6c, eof the slier on reaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg,t.r id.x8 ntnyq 0i t;p0em,9m pushes off the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast tn rtienmy t9ix;80q .dpm0,. 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. Atzn -ylj7wrptv *9(xk 5 the bottom, it has a speed of 7j- lwkx yztp*9 (vrn59.80 m/s. What is the vertical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70k4htic:,1-0 zlct b8usqv)o u m above the floor, its potent hc18- v iuk0)q zt:tso,l4bcuial energy exactly 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 frxctceo/sh)65ub4ci 7 om ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical ecx47bs i5u chceo6)/t nergy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy of 2- 5p1l;wm lg,capvvb: 9a,hdw 20 J. At the highest point in its trajectory, its kinetic energy is 120 J. To whhwvagp-;b5c vmw: p,d9l1l, aat vertical 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 amg:581 bqrfdn t a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above thrg18nbdf q5 :me 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 am0np)sxi6izhi b2vk/ 5t2hf m:vsd0b(*ww2 a speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed o5wmk0htfin 0 dvzs2s/)b xb22 i: vm*(aw6ip hf 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. 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 30icsw*z.7 r( u+ ziuxaje4s0/k 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 zss4z7k/r uia+0uw(ce i. *jxof 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(rj a* )4xb.ok,)xfkq dvv9am ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled j 0,re-xc4 d rfhd)i;deq9;qe30 cm away from the vertical axis and released from rest. What will be its speed;e,c 4d x-jredih9q;deqr f0 ) at the 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 initially uncompressed horizontal sk(gz.+d9 xq ce(z gj)u7hdko5pring with spr9.x(z(o7 d) gjzg+qck5h e kuding 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 vzdj7 :f gd7tsul2 :zv3 r0k.q22 m/s, slows down her 2000 kg car to stop for a red light. What work is done by the friction force against :0 .q2:g7zu dv sr7ktjzlf3vd 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 force9o+xs4wj(3ooe,dt a e between a 60.0-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 sli3ood,+x j wete4a9o(s de 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, level surface. It r p;k5 lfivd,5has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far will;ipvf55k ,dr l 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 a8nq),-rdsii v 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the changerv ,id sn8q)i- 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 b( /66bttur6e cf+cp8wk rf4 bof a 50-m high slope. If the work done by frictit6rbb+bfcupr6 f (4ctwe86k/ on 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 inclfl,k, ajfx00nt8- oe/1htx ywined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average fy /jo0af xk8,tltne1 ,w- xh0friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined at 2pr9)wu lmm37fsz 4c+ y0e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass af7)zf 3psc wml9u4ym +rter 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 4.hfwqxu+grzj*)f gx,, vx1ufv(+ hs a velocity of 7.00 m/s. What average force of air friction wv q),r+ 4v+usuxj1gf ,x(hhxz*gf .facts 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 rtt qkj ,/m+be7uns up a flight of stairs 10.0-m hkm+q7tt/ e,jb igh, 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 neededggaf8,6pd v+ 4xk/ . re:3vt5bnyd gzm to move an object with a constant velocity of 5.0 m/s. What power must be delivered to the object4+5e rzgkd tv m3 g8 yp:6fabgxv,d/.n 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 by a 1.0 hp motor that runs for 1.0 70,18pwyfrmo1feir k)y5mysmyxc st77)nd 3 hr? (1 hp = 746mp 3d rc5)y y1fxenmiy1,of7ktry7w 7s )m8s0 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 W while riding. How* hr ab 2kc*e o3w059.rcxwcmv much force does her fowbcew* kc9v2ho rx*05c. 3armot 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 +lhwjqx2ya6ixd3l )7j 7ykg/ the average power delivered by the engine? (1 hl 7 jgkwy7)lqh2j6xx+ad/ 3yip = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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