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

1#

What is the correct unit of work expressed in SI x*sgn;+- vvvi 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 motion3f; ; 9quregfl(l :obf en1y.o?

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 f ib63omcj-p.against a stationary brick wall, the amount of work you .cjb- 3pmf o6ido

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 ve,j+zssgupr3 4 ai *h-xrtically and is being held there. How much work is being done in holr 3,uxha4si-*+pgsj z ding 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 veloc*6ulztyh wg*:4d7f js ity carrying a 10-N object, the amount of w4jld7:*t h*fygu6w szork you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned re z5iv-b9b*oz )(vvfu)l uksz/( n9v to its original position. If the total weight is 30 N, how much work was d(9e)vivsz l )z-5nbovz/v kb (fu9ru*one?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the obje357mib zaxt6ict?

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 wke.dqpf(sc g ksc12ne* 58f3gork done by gravity while the ball goes up with the sign of ths5 f3ck(cep sgnf*k8d.1 q e2ge 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, oe +,d4de1c 7 g-mpba.hv ;jwa3jwb8snn a Force versus position (F vs. x) graph, represents7 awd-vdnh.e4c +3 gbsa1m bj;j p,e8w

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 c/rxos *w s06tq:(3te+vbx gfrepresents the work done by the force F?63tecro wqg:s0 x(sbf* tv+x/

A. the slope of the curve

B. the length of the curve

C. the area under the curve

D. the product of the maximum force times the maximum x

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; mv^2$ is

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object's kinetic enevb9f .q20gaws:rfjn5 rgy

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 tz-upa)u , mrm6he 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 mngx:bz)ezjred07 / /(*dy,olv *edbobject'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 movinmo5 b5r8w4zs .az7 ozqe)9mp0n lu q2mg at twice the speed of the car. Which statement m7warb 0pqzz)l n e5oo z5qms82um.49is 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 as car K, and car J has half the mass of car K. The ,-6np3xo-ezxgaknt2 kineti-, pxneg- tkoz 3xn62ac 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 and bounces back with half of its oribd hu(s*n,9.3kqxrj bginal speed. What is the ratio of the final kinetic energy to tbsbr(,jh *uxkq 3n 9.dhe 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 speq 1po smp 8n0ec2yoo2,ed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's masm2y1 oqps oe280cn,p os 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:z c-t(ml+ohwoe8 ;ei lu7ft 5.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both obc;:5+eo lzo-ult7i(8 te wfmhjects encounter the same constant braking 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 youejm m*op1l8f3l (qg+w0gkrm. ee h; 4gr car in a panic, and skid a certain distance on a straight, level road. If you4+fgwm0 m m; gk3p(hlerj8l* oe1eq g. had 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 the Sun in an elliptical or1ll:d9umx 1-b/czf hb bit. Neglecting any friction effects, what happens 1lub l:/ dzm1hcx9f- bto 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 principle.kjve4yjvp 2u/mg48+0z z -ma rxq1n4 n

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 system3s 6gg,gye u78zfbs-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, .d+y2vjdx +t8c dxjrh s;vt2 rest a height h above the ground. A second object with four times the mass of the first if releas vjdx22j.+;t tvs+hcdx, 8ry ded 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 to the end of a spring ckv cqu7gva( b2x12:e pauses it to stretch 5.0 cm. If another 0.200-kg mass is xqka c2p (2bv17uvg:eadded 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 energy of a mfe3 ma7rutgq41p h-n2,cyq3 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 tkp2)4 g/p:6rjhlc8nu)ue qju /p ;mnoree. Compare its kinetic energy K, to its potential energy U.)8p;/nonjupuep ) m kr426hg/juc:lq

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 an x5zfj.(;ezoik-9x- dmf x :z 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 heavyweh kilwwzww 3fky58+4*co, ) object are sliding with equal speeds along a level frictionless surface. Theyo zw +ifwyhwwwck835)k,e* 4l 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 wwd zej5j.fdd r pe(89ai)u/2 $m_{1}$ 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 conservatiyzyare: 2;/ u .r7sovson of mechanical energy for conservative forces/zersy 72.us: yaovr;.

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 fricti de5 g3z6 r(;/.al tjfmzp.kysikb r(0on is present), 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 building3kg bm( zy( p/itrz5d6fa.ls ;0k. rje?

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 ignore ai:+unx j0 yft7xk2cg 7nupbg*;)y ml/r 6i+rx fr resistance. How much gravitational potential energy did thxc:27uxpg 7+0uy+n;rx)kgi*b 6fl/ntmy j fr e 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 30ab2ze :dlo9 l-9u4jrp J of gravitational potential energy. Do not ignore air rel2opd 4ru9lje:z9-a bsistance. How much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation owfai:kxyf2 b3z4* b -ff 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 iso/u 6c( 7-p,gtsa(d(pv rurr / alw0xf

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 pou5 dpe y3jk14ower 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 a94vi63j sz mycn.0 nynot 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 yesterda2j 19hku9an vvnnc( 2awdvc2 /z oq2+f*oi s4ly, you did 3 times the work in one-third the time. To do so, your power output must49viqn a*hafndz(+ /9ucwoon1 2 vjcv2 2s2kl 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 constacyv xg(v74 :qj.pps;s nt acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If the object weig kupj: u2jjh+tkj55v ui0mn(9hs 90 N, how much work was done in l (2pvjn50h+ tjjmuu kj95:iku ifting 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 ci-ifl 7d8b2u rwy21m:vi+x :1ouh iajonstant velocity of 0.50 m/s. What is the work done by the weight of the a2 rbviu:27ii811dyx-ifjl w om:h+ u 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 u7j gklzyt96,ipward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 5 9z6g j,7iktyl500 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 org0,crsd t 6k0p7q1t for a distance of 50.0 m. What is the work done by the weight of the elev6ktr00 rop,7sqd1 gctator?

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 wit3*pbb5+r bno mh a constant force of 5500 N for a distance of 50.0 m. What is the*r3bbmn +ob p5 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 bx82qnnb4b o 8m 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 down a ramp, incli z87oqv3fbxwp- dgf15o/ gp/x ned 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 lita/)mcl s,z2bw tle sister Sarah in a sled on an icy surface (assume no friction), with a force of 60.0 N at an angle ofl2/ amz)b csw, $37^{\circ}$ 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 Fig. 6yu0 lz (t3io tx:v,bx/-1 shows the force versus thu0,/b:v lotytxx( 3 zie object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6sbr4; u l8qc-j-1 shows the force versus the object's position. Find the work done when tlq;jurc 8s -4bhe object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of 96dcozoqw/ 3 n.c3yyf the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work dd96 y c3n/qco.yzwf3oone 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 theoef49 ju/lmx - force. The graph in Fig. 6-1 shows the force versus the object's position. Fo-xuj mf/l 49eind 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 ho vzk2 t)2sx hz:i)ev0xb*4dN is applied to move a 55-kg cart (initially at rest) across a 10 m level su )t)vosxz d2:*04xzbvhi2k herface. 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 (initially at res e.ls-v f;vco 5g2t2ult) across a 10 m level surface. What is the 52 lcul2s-e.gfo; tvvfinal 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 cmu0js11h5 l hmuch work is required to stouhc 0hs 11lm5jp 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, wh4.fus xi uy-8qat distance is required to stop a car moving at 50 m/s under the sam fs 4iuxuy8q.-e condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 5p1agyhn6p b8a au )7j10-g dart. It is cocked by exerting a force of 20 N oveb7ja8 6up1 ny)a5ghapr a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N andza64w27lrfq z h p :50k f*n(z,cxlmgw a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The caw475h xgl02rfapz6 w :c,lmznfq*k z(rt 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.ng/krx4aivmsq / h,1 hay, striking the hay with a velocity of 60 /g4as /.,x h1vrmkqn im/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is move ev4bc 6 ((t*tzjyuv:ed from a height of 7.00 m above a floor to a height of 13.0 m above the floor. z4:tu eyj(b vvce(*6tWhat 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 ay:u 1)as htu-k,-xiywn inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done b,wi: -yu1hsayt - xu)ky 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 sprin(nchs.1r a*hgw(ee6 f3*p tbp g to stretch 2.0 cm. What is thtpg.hn*1 *we6cb esh 3( p(rafe spring 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 sprihr-srk5pyk .e. mql1 .ng constant of 60 N/m. How much potential energy does it store, y k51.rs-m. e rqhpk.lwhen 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 unco4i mrvnnj3sia-i(0d-z(yuid n0xgr 9a5x . 6mmpressed spring with a spring constant n3ya-g5mi usrir j.zndiiv(m 0 4dx0-( 9a n6xof 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 str8m(akflugm ycesf )bzk((4 4 suigf43h.)d)vetch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretck b4zg(egmf)yh.(4 a)s uidcff43v 8ls( ukm)hed position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initoz4c hcd+ :ij5ially compressed by 3.0 cm. How much work is r 5:dci+4zo hjcequired 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 top of a 50-m high slope. What is tsp3 / em-c9aswz*aq6 bhe speed of the skier on reaching the bo-m bs*6 sqc/wape3 za9ttom of the slope? (neglect 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 the top of a hill with an initial speed of 4.86kq n0fcgdqio 5.l +y0 m/s. Negleqg.nkdq 8 lc0if5+oy6cting 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 frictionless inclinedid69butcv 2dg7+fbmy 6+ uq2y plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical height of theq b t+v2c7y6im6d2 gfu9b +uyd 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 juu4i u,ib5;nabove the floor, its potential energy exactly equals its kinetic energy. H uujb;i,u 5in4ow 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 xuvqs/1+9r)rzzj, wz* ( xpaal5yh1f, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trax af ra,zypj*h1/59 zzxwvr1+q s(ul)jectory, 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 energy of 2k*kd,ew5q+i (hq9(+ /pb pjmlwnc,d n 20 J. At the highest point in its trajectory, its kinetic energy is 120 J. Th *,5wkibpqw, (+p jm(cld+ke9 qn/ndo what 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 at a point 45 m above the bota(t2v 6pqc9i ctom of a dip (See Fig. 6-2t pqi9ccv26 a(). 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?

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/cr + iq.ypey c+pb8wgb44 a,2,ly-pdk s at 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 the bott rc bl2ye kppi+y.a4y-4c pdwb8,,+ qgom 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 dtuw -c.394n6q goj flpoint 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 j4u3gc-l 9 f.6oqwtdn speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottom (jvp0cu: i8(mss dsmv )oc.lv6b *0ea 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 0.30 m away from the vertical axcdwfn9pm b(5p1*b56gha.uc4ml5 w ji is and released from rest. What will be its speed at theln(f a* .uwh1w45 mdmp5 c5cb69 bpijg bottom of its swing?

A. 0.42 m/s

B. 1.12 m/s

C. 1.68 m/s

D. 1.40 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 horizontaph zq19e dzx /3(yhm8gl spring with spring constantm8 y/xz 1( q9hzdpheg3 of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to stop for a re,mem-e v a.zt:d light. What work is donet,: .vam-eme z by the friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object 8epb: mr z0doza of64r3z4cb ,and a horizontal surface is 50.0 N. If the initial speed of4,zrbfo z8mb e:d 3za 0cpor46 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 kineuycl one)* ycu1u b+*4vm/ yjn95rc-ztic energy. The friction force on *u +/m uvcncyl5-r*z cuj9oyyne) 1b4 it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-k) ,nn4qa7 b 4fkuu95ijbad w0rg 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 change i ,uaak bnu5) nrj74wbqd0f9i4n 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 slope. If the work d/j-rq keg ep;q o:uo o*r-3s1.eaog*kone by fric-;ro s:jeoq*a1- g 3ekegk./pr*uoqo tion 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 plane. The plane ist15:g ts:c * zci+jbekg28tzg 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 watkb+5j1c 8z*ge2igts tg::zc s the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane i-fydwxe) 9(n- :wgvjqcmwj 2-.cujd+ nclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the)uyc-nc dw.q2:fj9w -v+mxgd j-ej (w plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikes the ground with g (b+uqa 1u64l*j .19yvoreog 2bmtxg a velocity of 7.01 4o x6otre+j(gab gg.* l9 vqb1u2muy0 m/s. What average force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a cs)npf2j a32xn hf93zj/n: qoflight of stairs 10.0-m hj/hnx)q: 29 f nn 2a3jozsfp3cigh, 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 wits- jxjtpx/ 6b.x1 /j6mtrs9jah a constant velocity of 5.0 m/s. What power mustp s9xsx1.m66 t a/xrt-bj/jjj 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 hpm vbg)umtw+r*52n6b n motor that runs for 1.0 hr? (1 hp = 746 5vmrnnmbg6) utbw *2+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. Hohr;je3;qx *n zw much force does her foot push withnqjr; zeh;x3* 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 t88e3g -xxr dcxw,r d-qhe average power delivered by the engine? (1 hp = 746 W ,e8 d8xqgxrcd3 -wrx-)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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