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

1#

What is the correct unit of work eoa rfhv3 ;/imc;kfuz* m1-zs 6xpressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no mj9 dyzf/ k*;ksotion?

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 statiw us gc(gf38c/6w ;lqfonary brick wall, the amount of work you dgug(f ; 3 wf8wlcs6cq/o

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 6v;szf55 ydkzt: u5y5kwv2w u+su( btthere. How much work is being donezz d 5wyu5f ky6u 5s5(;kt:+vtvwbsu2 in holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constant velocity carrying :jnzs/ 7p+dp:isqb a u-/ac:x a 10-N object, the amnac/:sxajz7p sb:: iq-+pdu/ ount 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 vertv*4ucqs w ;r+xically 3.0 m then returned to its original position. xqc *rs4uv;w+ If the total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on anc8muq t/n z(wmr.hg.) object do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the ho 8 lw,7kbesvg(3k:r sign of the work done by gravity while the ball goes up with the sih ok7rkw eb8,v(gs3l: gn of the work done by gravity while it goes down.

A. Work is + on the way up and + on the way down.

B. Work is + on the way up and - on the way down.

C. Work is - on the way up and + on the way down.

D. Work is - on the way up and - on the way down.

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a*) k*3k o9ywrp8o w6sgemho-a Force versus position (F vs. x) graph, representso ws*86moewkr o)ay h93k*-g p

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 positio* eu6hlsad .a;/( cvxyn (F vs. x), what represents the work done by the force Fasl v;6d ay/ u(xe*c.h?

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 zds f-0e /3wpm/ uro.con an object 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 an obfs2nwum/0 yb 5ject 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 is zero, then the object's kinetic zbq*zxwhjlu 2a: 18f/ 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 speun,iq .up ,gikqiy+01 ed of the car. Which statement is true about the truck's kinetic energy compared to that of the cui q.+,p1qy ik ug,0inar?

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 hamd 7 p fu +-0i:*wcke qdw;zwgasg3+t6lf the mass of car K. The kinetic energy of car J, compared to car K +g:fg7 kpmuw6t*0 zsd3iwwc -d;+qa e is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back wit9 popf sr y+tv+xkc 7(dp.8x:fh half of its original speed. What is the ratio of thvfcpf9t(dx 8:p+os+ 7 kp rx.ye 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 movin2q:i:gqhimh bn/ ettk,r loy-u o6;6 .g at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mas/ mqno2gkub. hti;y:6r tl, :eq-ho6 is?

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. cu5g o*uq 0ol ,dga,07r4a ;tdw vxdf8A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greatud,acd;4aw8g00uqo go * rftld ,5v7xer 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 in a panic, and skid a certain distance o91t7ntwv3pq wwyt h9dsn18y7 n a straight, level road. If you had been traveling twice as fast, what distance would the car have skid7y 9twnwy3dt7s n19qtw8ph v1ded, 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 njqg6an8gd d.i1 .0kyorbit. Neglecting any friction effectk. qy8ning d.d10gj6 as, what 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 prinqbo)og g// ox(y.na 9sciple.

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 potential ensyk*eml u7.-o s6p3abergy?

A. Yes, as long as the total energy is positive.

B. Yes, since the choice of the zero of potential energy is arbitrary.

C. No, because the kinetic energy of a system must equal its potential energy.

D. No, because this would have no physical meaning.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. b0*k02 sao txs A second object with four times the mass ox*stk2sb0oa 0 f the first if released from the 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 tx77ryx; 5w nhxo the end of a spring causes it to stretch 5.0 cm. If anotherxr hx775;wy xn 0.200-kg mass is added to the spring, the potential 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 energ3j7 so1 pq8l71d90xpx quvwq oy 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. Compare its kinetic energy K4 .6 z4r u2s,r.r qvkgt4euxo4gjyky), to its potential energ 4gr.t4eq44) sv6zryxkoyju.gk r2u,y 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 w0rr l33((dyje/ f/zw ihrh9tcar driving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are sliding with equal speeds ;ftgmkz/9m6b bb.ax2 nu9cx9along a level frictionless sk tbnz.gfm9b u6/992;ac mxbx urface. 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 uu 3-0tgt0cznj9bg l9,.n lmd$m_{1}$ 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 mecha/vmpfudl)hov z :)po.8b9mb1v-fd:7 a d pqo 7nical energy for conservative forces/7.o o b f o1f: z7dv)q )8ul9:p-mvhvdapbdpm.

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 buildin+k kgfoheb )t4 sd484qg, through the air (air friction is presenth+fqk 4k)o bsdt4e8g4), to the ground 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 energy. Do not i)n :zww/ggzr i zi6.7bgnore air resistance. How much wgg 6z)/i7i bw.:z nrzgravitational potential energy 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 of gravitati:8sl34 2 c ; wceljl il mc*b*r9vui:1kedlxc+onal potential energy. Do not ignore air resistance. Hm:c i :llil4 +2lbrexj*l98u3c1d*ec s wvk ;cow much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of con:d7;luac;kack46 fx(+ id9f9nnko n oservation 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 kiv iv)arrrx2s8o596

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 powe7tki-ru- s-yip dc1,fr 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, which is notyh/b57raszql eek ae-i*7i49j vl 5+z 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 diiu g rv8im5q,vf16nzu 7im;g59o y j*md 3 times the work in one-third the time. To do so, your power *m58f7qmjyiz59iovg 6 nugvm;ui,r1output 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, thes qo,-o 7z-l etey6x,l 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 helqmqq( w. rvd3+d there. If the object weighs 90 N, how much work was done in lifting 3v rq qd(+qmw.it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at a consta1kt8x no2g91k, ( kdjokv1neirv6 5rvnt velocity of 0.50 m/s. What is the work done by the(r1dxr2v,ok ke 1n i o198gkn 6kjtv5v 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 witzd.m z+ x )ir1qjsn+ whw)03rph a constant force of 5500 N for a distance of 50.0 m. What is the work done by thex)qnr 3w+)zzr s+j1id .h p0wm 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 witho- 5q(ya7 tuhbc-4dyj a constant force of 5500 N for a distance of 50.0 m. What is the work done -bc(-4o quy t5j7d hyaby 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 wp-cagjv da;rp0 6,i5fn.z ;5ge h1stci oec49ith a constant force of 5500 N for a distance of 50.0 m.-c i6. a zhi1et rjs,n4c pc5;0;ag5ofv9dpe g What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up along aqm3/jlgozp vp k/ ,1-0hpbj 8o $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m do;9.g aku exd*kwn 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 sist +5ouabf 02ofger Sarah in a sled on an icy surface (assume no friction), with a force of ff+abo05u2 og60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Figz ;5+fia;oium . 6-1 shows the force versus the object' umiz5fa;o +i;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 j45vfj:r j hv.xu2c3oforce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from u rh:fxcj524vjj 3.ov 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 directioe2lc - -2owfsk okjy7:7+bayz n of the force. The graph in Fig. 6-1 shows :sbcy7 z 7o -k22fok+ye-jwal the force versus the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6-1 s+mwzkmw5d 4(vhows the force versus the object's position. Find the work done when the object movw (mwkm+v 4d5zes 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 jr9,sm; *df md3pxl3z9*brv+h sve;h to move a 55-kg cart (initially at rest) across zm3*lvxpmbdv ;rfd + 9h*3, rs;jes9 ha 10 m level surface. What is the final kinetic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (ind.o e+mb:q :dfitially at rest) across a 10 m level surface. dq:.d: be +fmo 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 muqk.badd94+.hu, p xz cch work is required to stop the , 9zq4bp x+c.dhau d.kmass?

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 is rc/ w/95zjx o23nugb g i,kca+aequired to stop a car moving at +,c zxg9gcu ao5jn wk/2b ai3/50 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 praj2jzo-4n8tydh 8) .mklx4oh m6qaj:opels 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, assuming the sprino:l2 m ht8mnaj 4a-4yo 6)j 8jdzkqxh.g has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a vertical co4y*bgqn (8uhxw.c t9w/gle+ x mponent of 60 N. The force is applied to a box whichwetgl9ybxx+q*uwgn4/. h c( 8 rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, striking the hd;ru -w2r6dh yay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What isu2d yr;hwr- 6d 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 4n 0tl pbg-lfsl orejzxj55o r4:(*( t7.00 m above a floor to a height of 13.0 m above the floor. What is: r*5 tz(x4 5r( l0osofnbpeltjjl-g 4 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 planeo7jwq7+- sy hw is 4.0 m long and rises 2.0 m. If thyjh7+ 7-owwsqe plane is frictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring t-bs c2h2jsf 7 wwt;7pbo stretch 2.0 cm. What is the springs22btwc hwj;sb7pf 7- constant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How muwf hr6grij-.2ch potential energy does it store, when stretched by 1jwfi2.gr- 6r h.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 uncompres 2.gg1jt3e+;rut tfwssed spring with a spring constant off12+tttge wj ; sur3.g 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 constant 40 N/m from qawx;g;sl,9oj9 f d.xx = 0.20 m to 0.25 m? (Assume the unstretd9f asxx. w9l;;oqjg,ched 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/: zoger;g iz5 *x3mqi1m is initially compressed by 3.0 cm. How much work iz; g r*z5m3eg xq:1iios required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the toph;0m5 n nusml 4xp3e3x of a 50-m high slope. What is the speed of the skier on reaching the bottom of the slope? (negl mhpe xu03n5xn3s4;lmect friction)

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 off -.e92ehpcoqk-v-np2+qpsm pthe top of a hill with an initial speed of 4.0 m/s. Nee9c2 p q vk-hspep.mq2 +n-op-glecting friction, 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 fr9 u;a1f vep6nq7qobe 5ictionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is thevfp5 6eqb; ue oq1an97 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 u6,ttt)/xjj dap689q hn jwz/is 0.70 m above the floor, its potential energy exactly equals its kinetic eneru/6p )tjdxn 8zjqatt/w hj69,gy. 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, blas zhznhm1v- akmnth6*:7z44xi ts straight up from ground level with a kinetic energy of zmm*4zkahin- h1z: nxt674v h40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic eneulei xe7))lzr24jrte g ft0 1*rgy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vle gr0ue7xr*4i ltj)z e2t)f1ertical 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 bottoakzk00,c/82g;bljds 4iremm m of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?;em gszdjm,0r2a 8/ lic kk0b4

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A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m above lc5qn/y*w ;i7fm brp;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 above5il w y/cb;;*7prqfnm 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 aboveo(u+)l f:0z bi g,la 2zucz.hd the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what willhduf zl0b ( :z)a.l2+ciu z,og be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

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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 spdl;y)c9 n) (r smh)7ibjyo.gjf wie; 3eed 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 0.19 m away from the vertical axis zt0i6e y,ukpgmm3;* dand released from rest. What will be its speed at the bottom of its swinu6d,;gykmiz te3 m p0*g?

A. 0.257 m/s

B. 0.686 m/s

C. 1.03 m/s

D. 0.857 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 init.3/pk gum2whr2tpqk (ially uncompressed horizontal spring with spring constant of . 2 kkpw upqm3/hr2tg($2.0 \times 10^6 \; N/m$. 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 tovw-m)w-gpy9 b)*4g hux n8rtd stop for a red light. What work is done by the friction force against th9* v-utx4 -wg)mg w r)hp8nydbe 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 obje1ep- qjig 6*d3n(q/8cz mrqo 4id7rrk ct and a horizontal surface is 50.0 N. Ifnc8* jqp7dr1q/rmr4o(ki ieg63d - q z 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, level surface. It has 24 J of kinetic enl)7kv sn ;o ud(n1gd6wergy. The friction force on it is a constant 0.50 N. Hovldd(17ngw;ko) su n6 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 appliedw + x;f5tp-b8hia(v,rns d7pnw;htq2 horizontally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the w+bh ;nq svfhtw (n-2a5ti p;7x,8p drmass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high r1+f;icdaz3 p slope. If the work don1ip czf3;+arde by friction 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 pushed up an inclined pla;9yq5v d+ nhn/9mhhpv+ogrehdo.q 1 5ne. 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 the9h+/ h v qp9r;hho15 m5gd.dqov+ne yn 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 rest at ttp1s0c:e 4v mwhe top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m alo wc:s4tpm 0e1vng 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 *9ve mq8ao k :,0k a1ugyy)wuy10.0 m, and strikes the ground with a velocity of 7.00 m/s. Wh9yo)u:m0v1qgu kyw* aay ke,8 at 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- 9ckl+ysn 5.0qu+nq e*melc5 vkg boy using energy when he runs up a flight of stairs 10.0-m .5nv+*cce +yn0qlsl5 keq9um high, 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 object with a constant velocity of 5.0 m/io6:bd7e6 cf/rzp xz*s. What7/p*c:edzz xi 6 ob6fr power 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 by a 1.0 hp motor that runs for 1.0, fzx0 u2(mcx lhjjmda*+3mf( hr? (1 hp = 746ux3zfxh2l jmfa j,( mmd* 0(+c 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 .3h3rp cyv ilqg/dx;:. How much force does her foot push with when she is traveling at 8.dp :3gqy3c .rv;hl /ix0 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 mm+irq r tj8*c9;exb:s/s in 7.0 s. What is the average power delivered by the engine? (1 hp = 746 ;8qms j rt:ex c*r9bi+W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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