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

1#

What is the correct unit of work exp4nppp01rkg0 djjr9 a33 iti7r ressed 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 ou5ymu5x)/xo there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary bricysnr g1 ea3o9d/vjo-i qqx8*v:(5c wgk wall, the amount of work you (q dvgjnq og5:rcey v-x*so1/3iwa89 do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held there. How much wo4kp.z pl (c)zbrk is being done in holding the box in tblk(cpz )4 z.phis 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 forwarn y vd36j+ rrd764fhfrd at a constant velocity carrying a 10-N object, the amount ofy7df4 f+r66dvrh nj3 r work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned to its oril82n.4:kvnc0z iunj- uon l-xq+3l a bginal position.3xn -z.u4 c bul0nk:loail8qjnnv-2+ 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 w73 y4e)fb0xx xf:;r h0tckvn 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. Compare the sign of the work donewrt+/osz,6 xsr.zb z0 by gravity while the ball goes up with the sign of the work done by gravity ,r/b 0zx+r stsw.6ozz while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force v10xa h1gs.h6wq1tdxd1;-ti :gp l k9gv2wghwersus position (F vs. x) graph, representsgt waq p9vdw0s:x.gdh;1 1hih 1 6t1kwg2lgx-

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 versusx,x(g+h wwcn7b y-z 7p position (F vs. x), what represents the work done by the forcg,y p7( x+n7bwzw xch-e 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 objed.evcl1cnr2bo38 w03dot 2tdax6 c: ict 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 3mqrzx 6n.xpl: 8ewy +object is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on x;575 2 yqvzbw5 gxk6hsr 6ig,lam gc91.vpohan object is zero, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twice the speed ofn(o+dssl0 k3u o5,dj q the car. Which statement is true about the truck's kinetic energy compared to thaton ukl(30 d jsq+so,5d 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 us nw-l-86,wqrq*y bv car K, and car J has half the mass of car K. The kinetic energy of car J, compareq-qy-*wnlu,rbsw 8 v 6d 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 itpj,l j+plt *2ss original speed. What is the ratio of t*lpj+t, l psj2he 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 y wr2cto5u*/o a pebble is moving at a speed of 5 m/s. If both o2twor*y c5u o/bjects have the same kinetic 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-kg maa tceuk ca- f/n65t9anvv9afgj*4* r5ss is moving with speed 4.0 m/s. Both objects encount99f /n* -5ane5t gk6vvra *fa4ajc tucer 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 your car in a panic, and i7t+eq4la qlbvi626j skid a certain distance on a sb4 6a7q2v leiqitjl+6traight, level road. If you 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 ellgy qk+ r+wan*-iptical orbit. Neglecting any friction effects, what happens to the kway+ -q*+grnplanet'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 principl5gt,tzu75sdyl -y j0 le.

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 syyas:8c +oxqcbs 13i m3stem to have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a heixc* bprp (54ph 1/b: de3iz03mq lxlrvght h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of thebb e :mpc10r lppr xv334q/*xdi5hl (z 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 springl/ byvh.x 4mzk1;ugyljwn4qciz 16fe6-p4 (j causes it to stretch 5.0 cm. If another 0.200-kg mass is addefp1 yzeq4kjv4l6n;yl4i gz6h j.xm/u( wc b1 -d 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 /skf.k)bkp 1egzls4 c:n q+6venergy 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 )qcknzr2i v28j2gi(c its kinetic energy K, to its potential energy Uvnz2c i()k ricgq2j 82.

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 4d pi+in5s1ija 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 wit z guprc5vz:;pc;:v* gh equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which riserpp;:z * :v;c5v zgucgs 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 6hc1wb ly h*1lsjuuj5 z5xr.:tvp jux 1 +3d-c$m_{1}$ 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 n cu7*9 ys9r7.hccgk hmechanical energy for conservative forces.7chc g7y9u 9c.rh* ksn

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 aio*ml3+a6c rzgiv1.z ar (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at tag 6c m zi.zo3+lr*1vahe 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 ;us,.).g8q x veo6oluntvz-k of kinetic energy. Do not ignore air resistance. How much gravitational olnvg.q s. ;vu)8zeuo , -6tkxpotential 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 +( dygvx, 5w/ a53evkbfq5pus30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did t5eadb,pk vv+ xwq5uy 3g/(s5f he 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 conservat9c2o)x s6jdjcsvk-u; ion 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 q.kpos8w d-3si1n v3k

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 7rpp/fv+8p uxin 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, whxf e.dcqm)8y 6ich is not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work )zjl4pn0ghw (in one-third the time. To do so, your power output must have hgl pjn04 )(zwbeen

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 co u rsck7evjs8* 6:g8 gf)3pnk9a* cyao+xz3monstant 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 weigh+ubh uy+ /9uuns 90 N, how much work wa/uu9h+ uu+ nbys 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 t0 zcoq7nj+:p anr,;nahe air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of thnc pnn;,q 0o :ajr7a+ze 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 pul fpccj5 3hg. ..1dpqc+ +okwrjled upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the dpc 3.+1qgr 5ofw.jpc h+.kjc5500 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 :l/sqaty ep27: f0 wybupward with a constant force of 5500 N for a distance of 50.0 m. What is ty02qp: 7/tysfl :abwe he work done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constantz+:po )1hsnr x force of 5500 N for a distance of 50.0 m. What is the net work done on the el:o rxp)+1s nzhevator?

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 upr: zwi qvlr :(1g*p(fq 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 8.8az z0yc kb*. 5,abyws0 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 Sarahcfxri/wusq j:01z.,oi:mp k5 in a sled on an icy surface (assume no friction), xwfijz/o,k s.q50c1 r:iup :m with a force of 60.0 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 Fig. 6-1 qrjz b i8:d1s/illor-8edu2(sh8d:le1lb rrji-d u2oq(/8s ziows the force versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph t:uq/x9xh 4q*+ w5e1bxtmc ye h/lsk*in Fig. 6-1 shows the force versus the object's position. Find the work done when th eq5wxx:b4uhx/thq k*ey19+lm*t s c/e 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 ini/d x +djhr0(pkg,s,p the direction of the force. The graph in Fig. 6-1 shows the force versus thppk si gr+ ,j/dd(h,0xe 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 ifplf t )oi4l9l .2ja6pn the direction of the force. The graph in Fig. 6-1 shows the force versus tlofp4a6)9ip lj l2 t.fhe object's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at rest)fr35q.jfmn5zz xg 8c 9 across a9fxj8cgfnz5 5. rmzq3 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 c-i*4zgnfdu+5 e96 pjet) d5jtent 3 wcart (initially at rest) across a 10 m level surface. What is the final speed of theg*eij3u+z 5n ewcd45j -)tdp f9e6tn t 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 much work is requirnp4 k1t nyyc/xno( d59ed to stop td/oyx591n4n y(n pck 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, whq -n)(vgpe3c yat distance is required to stop a car moving at 50 m/s undevpnq c y)e3g-(r 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 pr4dv 4l7 ulyx3 qwhk,t0opels 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 spring has negligibleu3x4yq0hl7 ,ldt 4w kv 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 howa l p+w3rk7bk3p5 8ufrizontal component of 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kp3bwla5u+7kw8fr k 3pinetic 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 horizh5cz ;(pe c w,kpyrjkx5r96 y2ontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penx;5 y(cp9 ehw2c,k5kzjryp r6etrates 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 moved from a height of 7.00 m abov8fulkp*4;bs8 grzouu (( vg +ne a floor to a height of 13.0 m above the floor. What is the change in gravitational potential energy?plrguousn (kf*(4 ;+zv8gb8u

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/3ss :bl(fm4i*9w peppue / sh inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is fres3 /uwilpm(s /f9:ppsebh4*ictionless, 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 sprinjgkol kug -l hj59+7+wg to stretch 2.0 cm. What is the sp7 +o9l+5juh k wlgg-kjring 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 cokax(o;8oul7vs 0i a/w nstant of 60 N/m. How much potential energy d/ ;a7vo(80swkio ua lxoes 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 initialli8mfns4k8rg1t 5ny5 l y uncompressed spring with a spring f rs kngy58tmni l5418constant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to yn)6-f pisxs q6 gppdg 0/ae77pbc1h1 stretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unp0cfsy7bgppiqxnsp- 1 6 )ae6/g7d1h stretched 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 constan3:f : qrdgzt4jt of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an additional 4.0 c zjg::qfd 4r3tm?

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 thuad .rg6pe q(j2 ey)pi*j6ib/e top of a 50-m high slope. What is the s2e66(aq/pgii u er.byjjdp)* peed of the slier on reaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with agb*p(1s be-jfn qg(h*d1gg (zn initial speed of 4.0 m/s. Neglecting friction, how fast will she be movi( jsb gd f*g1- zg1(p(eqnghb*ng after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bottom, it has a splg p; jmc/gxh +58a0u rke/pd6eed of 9.80 m/s. What is the vertical height of t dgkehp// +86mgc x5j a;u0plrhe 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 tgiwxi5 dg 4c3x0s5j *the floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it movingit3xjx wsg*0d 55ic4 g?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground level with a kineticjaiks.x z3: a7 energy of 40 J. At the exact top of its trajectory, i3a. 7ax z:jksits 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 gro3;zal .kikd7u und with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy i k3;zalk i7u.ds 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 rest wi3r 9v0 f/ygtat a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will bw tr3g 9y0f/vie 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 wc/b 6(tal+ (o p96g ylbecmc.a speed of 5.0 m/s at a point 45 m above the bottom of a dilo w/l9ptcb+beg(6 m a(cc. 6yp (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?

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 poinkrv:z -x+ ft.c/8d zmet 30 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the /kmez8 -xdz+fc. v:r tdip?

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 qz64hwmegd 0 g+*(6rf0 dmspz 7 ogda7at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 tw c;k t:tit5:cm away from the vertical axis and released from rest. ct5: tt ikt:;wWhat will be its speed at the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially unco:g bi6tvvst ,)f1kp7jmpressed horizontal spring wit b)gj7f :sp k6,vvi1tth spring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slowv- op;9)r ev;ng jq dkdk0k1.zs down her 2000 kg car to stop for a red light. What work ikrk.0k on1)e-z;dj9q; dvvgps done 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 and j5io3t r6bg .ma horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what dibjm5. 3otg6ir stance 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. ind ti5ml-1.(qo af0 d It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far will it sl-l.t(0fidqi1oadm5n ide?

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 ku ,rxcum,-8m 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 mass is moved a distance of 10 m, what is the change i-xuu,k8,r mm cn 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 frombkx8o0z j: g7m the top of a 50-m high slope. If the work done b 7 j0zxkgbo:m8y friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is 4.0 m long 6/ fc ytgw-t(cand rises 2.0 m. It requires 3200 J of work to get the box to the top of the pf6tcycg -/ (wtlane. 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 resb lp3n/ggi,28yq z( pa +f,az1wqjk:it at the 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 thez g1zjaqf3 2kg+, /wilaq(,8i: pybp n 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 10xtlf.acup 4a)x :*b5 q.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it ap).*afl4 :c5 xtqxbu 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 usinow4uh za .z(p8g energy when he runs up a flight of stairs 10.0-m pwz.8 (4 oazhuhigh, 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 a7pqlxm.u- n +an object with a constant velocity of 5.0 m/s. What power must be delivered to the qx.ua+ln-p m7 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 run ;9e3nc/3rp aj p3eo4c)gbegms for 1.0 hr? (1 hp = 7g3rnj) p ocpe93 beaecg43 /m;46 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 97fax + syexp)while riding. How much force does her foot push with 9 ps yaf)xe+x7when 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 t)rkn0vnnsc5rp)-- e pt y)qd v/.xlp6he average power delivered by thepn) --xnc6r pnl k0td 5sv r)ep).qyv/ engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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