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

1#

What is the correct 7r28tuqm z65e;yks 0*q0 xj n y-qfmpuunit of work expressed 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 n e4niy,l) gvvx:*ms. gti wkbv/)ua30o 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 bzp0 ef1zr8v*yrick wall, the amount of work yo1fzz p0ery v*8u 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 8x e9d2t jsss.and is being held there. How much work i.x2s8s 9ets jds being done 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 hor i/yi 7kes,(-vh nzg)38ad(d)fe pgci izontally forward at a constant velocity carrying a 10-N object, the amount of work you do (yn87pi kf iz,sv)(dh egice-a) /3dg 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 to its original pobw2br 7, ;uf in.iia/zsition. If the total weight is 30frai2b inw u,; bi.7z/ 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 on6x8*-.c3gccnhzbg p u 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 straight up. uf2mijo0i) ;s Compare the sign of the work done by gravity while the ball goes up with the sign of the work donii2 omus) fj0;e 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, ev/9dr1 :gdrwon a Force versus position (F vs. x) graph, representsv r:w9dg/1de r

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 vs2 rbt++tpl68vj exo/ y. x), what represents the work done by tht v8e bprl2 xo+/+tjy6e force F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, thbslr r :t3d7s t0te9+gen 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 ob n*cjsea.y ;tfc9k. 0aject 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 ener+05x-u dd z azx-wwre:gy

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 asp-(+st*4(pao4bem*ir p gkss-ethq ,vhn 1,r a car, and is moving at twice the speed of the car. Which statement is true about the trucp -eg o tsm eh,qs 4h(*r1p *+ia(tkspbv-rn,4k'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 q5 r0w,tdu y o u7ca38bxta6b)the mass of car K. The kinetic energy of c)tc obxu5u76w0draa38y q , btar 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 or+ 30 qt: x(qurbtx swkv5pj3v;iginal speed. What is the ratio of the final kinetic e qb5 u3 v0k3xpxtwv:(r+sj;tqnergy 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 odxmb(86(ayvjj +b qc2 f 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same k vj(6 xb2m(ad8q +yjbcinetic energy, what 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-uf o7rc)(x g(ez- it len)g8y-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest.( zee8x grl)oyc(- -7)intufg Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a certain distance on e pz*cs. 2ajbmwvtk6-l2 9an0a straight, level road. If yovz -0 sk*w.cplb292etm anaj6 u 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 o.bxiaa/toc p7*j4 t,xrbits the Sun in an elliptical orbit. Neglecting any friction effects,b.xtox a/i4,*t cjp7a 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 princq+auihre;q ghq(k )5g+ 0 jn1iiple.

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 negat jadt:tcw4p(7 thj;w) 0j :gqiive potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the gro2- fu* .)xagl i0hcjt0*m fkmrund. A second object with four times the mass of the first if released from the same hf)i*2h-mac gx*kjmlr 0ut.f0 eight. 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 causes it to stretch 5.0;dx rj2:bmwf-j9i 7rf cm. If another 0.200-kg mass is;2f f9j mirx 7-wb:djr 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 zfgjevj 5.6+3+rjqq fenergy 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 K, to b:xnw zmkou r0lim3r ud.6: (:its potential enermmndwrk0 uu.:x :6:3bi(lr zogy U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving up 0i ql gxut(j.7o45ndya 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 a3m;8:,x ,wyuc gn5 nc1w8 f)mgxss hbw very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a gre 8,suhx:,;my 8)m wnwbgg n c5sf1x3cwater 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 9r;u09ji zfi n ki.w k9vr24wf$m_{1}$ 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 conservativ bk+i0fc.n y)ze forces.. 0bzkyn cfi)+

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 buildiygy1v)iu6 fe: or 64kung, through the air (air friction is present), to the ground below. How does th: uyk1ufiey6 )gv4r6o e 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 ignvh ) ij:zinxw9/ (jvrd6osz 70sld-y(ore air resistance. How much gravitational po6 zd jsx:rizd y )7o/(v9-(v h0lsnijwtential 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 distanc h/obw65rffr::t o; qie and loses 30 J of gravitational potential energy. Do not ignore air resistance fq;iro 6h5:b /:worft. 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 conservatioz+vdg woq0 y*9n 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 isj6)znq p zi(v6ly li ,jg41-f8 3sscsomyg).a

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power expressed in SI unit52e+j v 6yd9t3yf3t7x t gxmtbs?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit o p.haxj; zraq ;wk( 7qfymuf983g.pm- f 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 o0-2 mksqm2gi2 l:q qn w:kfnt;ne-third the time. To do so, your power output muqmsqtm:nk222lg :i;w q0f -k nst 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 consta1 k+/ b6o jy3iy5gq*eklavx6 lnt 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 we;vw4gu p 7/u tv-vkyotjt1wi(l+gn12 ighs 90 N, how much work/yutuv wl+-4g;1jvopwtvt 2(k7nig1 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 distance of 1.0 m, at a consta,*kht)fgtuh1 z )dfj -nt velocity of 0.50 m/s. What is the work donef*zhg),h -t )tkduj1 f by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a d q xm ()l hbunapdn(i6-dy(11x w9v,xlistance of 50.0 m. What is the work done by the 550dn(xqm1h (ax,l )p vdx6 -n1l(y bwiu90 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 w65 agjr*;gzkc;3 bucc ith a constant force of 5500 N for a distance of 50.0 m. What is the work done bc;a r; k *jbgz65gccu3y 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 a5/m )i39 usvf7pixgeupward with a constant force of 5500 N for a distance ofixaps5 vg 7/)9if uem3 50.0 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 6n:p)hxi,6(ks1vnxvr8k pu (o.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 hz8fwh e 013w.j(pkvx.0 m down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sq 69s 1cazu5jiarah in a sled on an icy surface (assume no friction), with a force of 60.0 qj5az u6ci91sN 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 Fig. 6-1 v0 vec/e-3i / jtd*bzy shows the force versus the object's position. Find the work done when the object moves from 0 to z3 cie-0 b v//ye*jdvt2.0 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. 8e uf+6;j;a5 *(myvhtwh rfc0f:altha b-lu-6-1 shows the force versus the object's position. Fi;jaff6ehbyhtll- +-8; 0h 5ua aw (tvcrfu* :mnd the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig7p8hebqu4 wpk7l.f,qzt: b h 9. 6-1 shows the78,bbkzqfp:qw9. 4hu te l hp7 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 obj* zp*vo/wm l -f.bt7wjx(z 5rha m-rbkvz503nect in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 6.0 zpw-r v*-(lvzoj*w z55mt7h 03.m/ fab kbr xnm.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initiu/iafa*c8l82 v wm zo-a 80fgually at rest) across a 10 m agocffl2 0i-8*az/8u w8vua mlevel 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 cartz/oi26 i -ksow (initially at rest) across a 10 m level surface. Whai-z/6ki2o o swt 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 5sf*/+sy(tr0 hjdz a+j.0 m/s. How much work is required to stop yjrsfa+ j0*zt h(sd+/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, what distance is requlymf,yn7vf . : zs459.nyya- m0xqlmwired to stop a car moving at 50 m/s undevf47-.l . 0ln 5y,q y mnys:wyaxm9mfzr 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 g/tl- s.qk um/iun propels a 10-g dart. It is cocked by exerting a force of 20 N over a distance s/-qu lik.m/tof 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 and a vertic kmwvy mwaf+;l1 m(d54al component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from reyl+k(;mma 5 4mwdfvw1st, 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 horiz75x 9v86mcuku b+c,hviy okw, ontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the a, k uxc 7+96uky8iomhc5 vwb,vrrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to 0 7pwn )+wyddsa height of 13.0 m above the f7wd) w +pn0sdyloor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m long and rld3fn;limn kzr (tzf*b+7etr, 55 2iwises 2.0 m. febz tl7f l 3zk,+im in2 *rtw5(5rnd;If the 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 sprink(t ln7qd,1hpg, causes the spring to stretch 2.0 cm. What is the spring c(nkhq,7lp1td onstant?

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 potent0566w rfwhkm8 iay 2p q3cao*dial energy dfo*2w6p 0y6a ri ma3d5hk wq8coes it store, when stretched by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed spring with a o/)dim:u (:zvyxe vf8s.cap 3 spring constant ypiv(xz::d .amusevcof) 3/ 8of 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 stretch2h y:4vm3vcv s a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume 23 cyhv4vs:v mthe unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed i4hxe*aaa8p 1 by 3.0 cm. How 18apa ixahe*4 much work is 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 fgj9xj9k xt5p 6g :eyp1rom rest from the top of a 50-m high slope. What is the spt gp9:jgpx96jek 51 xyeed of the skier on reaching the bottom 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,loi -ghd30 fb(6oj;y uno*6cf pushes off the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m in elevaifyhb03 n;- lcoo u* oj6d(6fgtion?

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 frictionl.,o oxt8p:y-ucslf)o +y a1iv ess inclined plane. At the bottom, it has a speed of 9.80 m/s. What ,iu t- 1cl.yof+)yoxpavo 8 :sis the vertical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m above them1s4gihcsrf 0+ k(26 uwbssf 7 floor, its potential energ6 hsr+s(ussf7 24gmib wk01 cfy 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 from gxhb5s:, l06kuijlo oz/-b .v lround level with a kinetic energy oj -zo,il :o k56x0vusbb. lh/lf 40 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 energy of 220 J. At thea vw*;xp,b.r0u:alw )y ljws a(4hi,m highest.j0ariwsv4hl ,xl maw; p)*: w,uyab( point in its trajectory, its kinetic energy is 120 J. To 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*vdj/5mct/, 0f nad mb rest at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speedd0ctmb favd*/m5 n j/, 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 aysn7sbgkm9 ynq4 4hg- v6bg ,. speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig.b4,6 gnmsg-vb.y4ng y h7sqk9 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?

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 abov1uxz53w at.l ze the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the tz.ax3lzu1t w 5op 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 sfqxk5* bo/ o8npeed 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 isrj7 dbmskr*x 41jao0 0 pulled 0.28 m away from the vertical axis and released from rest. Wo0js7 *krjrx1b4a 0mdhat will be its speed at the bottom of its swing?

A. 0.389 m/s

B. 1.037 m/s

C. 1.556 m/s

D. 1.297 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 horizoh)q,c+ hoe6jtcf1 17*g oar fyntal spring with spring consth agf h7y1,or)+q*c1foe j6ctant 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 kga)s, qmf4)j h8mzwp7 q car to stop for a red light. What work is done by twj87zmmhqa 4pq)), sfhe 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 anuuxp i.p c1n6+q(j s0id a horizontal surface is 50.0 N. If the initial speed of the object is 25.00p(6c ujqu.xs +inip 1 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 kinojq: 80i1hdd2- ozthnetic energy. The friction force on it is a cojn0izqd182- hth:d oonstant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on vkxbinu z 31a,e+ex:0 a level surface. The coefficient of kinetic friction betev10ekxbin,x:u a+ 3zween the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts7 q:j0y6 s)3(bwueud kfxmp* q from rest from the top of a 50-m high slope. If the work done by x63q)7fes q0j(: uybdk mwu* pfriction 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. Tkai nnxv)ey/ 5r,* xs/he 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 av/n/,s)y5xx *rn iea kverage 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 too.j6qdf m .h3m-q- d*ty*6k;cglcuyep 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 along theqd-ju ; -*y6qm.odt3*kcycm6g. e l fh 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 dre1zq v5 w;rt-oopped from a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/ e; oq-t15wvzrs. 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 boy0vuhanwwy8lx-q h f 3bg ))b.* using energy when he runs up a flight of stairs 10.0-m high, h)8ub gn qyw.-bl 0fvx a*w)h3in
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 moa49z bn8cyo o6wte* -ave an object with a constant velocity of 5.0 m/s. What power must be z 9bt oyoa48e-wc na*6delivered 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 hr? (1 hp8/bgp8/d /r0 dqesqzq, ad ;wqcq(dz,ob 2yu) =q qeb ,rqy8d8zoz/ ) d0q (s/pbd/ga wuc,d;q2 746 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 5h(ato huc1n)2 00 W while riding. How much force does her foot push with when she is travelio)h htcu a12(nng 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. Wha0auf7xbdm):. ic v.4vrk w ,gkt is the average power deliveredcf 0a:rk.mvw)bkvu 47 .,igd x by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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