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

1#

What is the correct unit of work exps95a yj ;ghb6zo. qtagv6w*n )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 there is no moim2 z *mb3nq0h3 1fzwotion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the amou v-1:mbuit 7s.ocz 6shnt of work you dv.icu76 mos szb-1t: ho

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 h b go1 y7hb53q1c:wahe ka2sl n+lbw8)eld there. How much work is beinwlahb 3aes)b1 582 lg:oqychkb 7wn+1 g 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 horizonta1mui; iv8z l1wlly forward at a constant velocity carrying a 10-N object, the amount of woru ivwizm 1;l18k 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 liy.hssi;5 :gc pfted vertically 3.0 m then returned to its original position. If the t:5 ;h .sicspgyotal 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 actni sv w/;dcv gk+.2o5cy30grzing on an object do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. voahope,6,-;at5i 1 zv xhs8dCompare the sign of the work done by gravity while tp,oo d 5 8vx,;a1 vaie6shhz-the ball goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curvem bm.m:pms6-sz / b0tf51wu.2r 6pyplrsj8 d t, on a Force versus position (F vs. x) graph, representssfzj/ .:5dl wsmr pb6b1m-tt6m02 smp u.pry8

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 represents the work done 8:p(l spr1 z8,dub9 (g nt *hjykbdn/vby the force F?rgnjd/h8 u1 d,zp:9bb8lpvs*(n ky t(

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 o( ,u3i r+ gn0hpw9brnibject 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 object is negative, then the objecnbz 3 ,rfa6f6lt'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 enei f)a4iq*mj+q :x j4eirgy

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 ofw u4n x77byvdm3f+b. x the car. Which statement is true about the trb.nb+wuv xdm73y47 fxuck'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, an64qy:0kdvue u d car J has half the mass of car K. The kinetic energy of car J, compared tov q0udky 4u:6e 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 bouncet-/ d0ql fw1y8gs o4zes back with half of its original speed. What is the ratig1d4/8zweot q0-ly fso of the 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 o6 f0 tv)uk0/ wl 2itg(pjy h.skfb,oc7f 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 ratuhtcvgof/p0is,j60 l)fkk 7.w( y2 btio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is moving wit3ua3e0k)c6w v ucth w:h speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to t0 cu3wh:)vkec6w 3aurest. 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 distan: )mnb+ ( hr 0 eikhc.ud31nr)*weesgmce on a straight, levemuw ekr) em:b 0 +3ir.)(snh1ncgd*eh l 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 orb/*/l;qyp1vpos bss4hr fi 8( wits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet'sbryp8/ss wv*/hsp4lo;1 fiq( 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 prinzl2og3*p i k/r pabq/*ciple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential ener8dt5-m tvs3goq m l:3dgy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. A second objs,3xl,-y.k/derz6xw(hb ky 95rd/m m zlcl) aect with four times the mass of t3bzws 9cxlmk.x 6k/r,rlym d()-ea,z 5d/hl yhe first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it to stretch 6x pqjju8 mjw:9w nq4*5.0 cm. If :j 9jj46xpnuwqmq* w8another 0.200-kg mass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a sy 0 j5lo2 vf9d2w(+yeei(w5vdau g(adustem

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 tj ehd.,(bde 6 utjog4)ree. Compare its kinetic energy K, to its potential energy U t )uh,.(j4edbog d6je.

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 a 9(jlxj9o 9sa jhill.

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 ob x,e0h9xbnu.hrr,0vy ject are sliding with equal speeds along a level frictionless surface. They both slide up the same f 0xy.r9hrv,0ubh, nx erictionless 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 d/ e+3n*cm*awe a:pnx$m_{1}$ 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 c l xzi:93vpkiqo 9hx)fc5,/v tonservative forces. :cx)zklh q3ivo, p9tf vx5i/9

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 k9 re 7k1g 9i5si3h0v:afgj uxair (air friction is present), to the ground below. How does the kinetic energy (K) just before striisiv 5 xj:0ug71a grekf9 h39kking 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 ener1fy3jo4u t sca5e5is *gy. Do not ignore air resistu*ess o 41535jtayifc ance. How much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational potential energy. f8lwj5w k4o:w Do not ignore air resistanc8w wfwoj 5k:4le. 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 of energy2g4dn,zuomq 95-ed aj.

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 is6/c ) ehfyjk5m

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 e4kttrjsmfl u*c: (.3power 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 not a unc6up hq a/.,z)asgp q 5xgkl:9it 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, y oz0c;ylmo1xc /uj f-3ou did 3 times the work in one-third the time. To do so, your mo1l3/c o y;zuj0c-fxpower output must have been

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, the car's engopr.sz;p2iv -uyfd, ;ine 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 verti6-ejnj+/x- b eo6vlf htzg078 km2 gzcleyn1 (cally 2.0 m and held there. If the object weighs 90 N, how much work was done in 8 7 cg-26 neb+zhzlmolnkje6-t( 1xyg fje/0vlifting 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 updki5ps- .g6 wo.j;9c1br/hx v ykrsj , in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s.p19hs5jk-jkbxd. wv.ci oys; g/r6,r What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a corow -9i9 ;bcdf8 czt eryr0f9r,8 4tkynstant force of 5500 N for a distance of 50.0 m. What io-ir tkf, 9ze9d8y90 c8; 4frcy rwrbts the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with( qz-7z 1ymfmf a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of th yz(q zm7-fm1fe 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 c3rawxgb-+y) txr p46sonstant force of 5500 N for a distanceaw +4grpxxb)r-6 ty3s of 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 6.0 m up alovx8yzg dnt , 1i3bj(r,ng 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 fruipsl5cxq xty26w 79e4 w (z9vywt slides 8.0 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 Sarah in a 0i bu)2ahmq; w wg+jy1sled on an icy surface (assume no frictio)gw02y+u q1mia wb;hjn), 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 grapmmrk)ivit9*4v )* x myh in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 2.0 *vmri)v )k4*ym tm9xi 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 thmxy;danw i53c ;i64xge direction of the force. The graph in Fig. 6-1 sh 45x w n;xiadg6ymci;3ows the force versus the object's position. Find 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 Fig. 6-1 sh5;ul)h8kj6 8uhv7jbc ,og fycows the force versus the object's position. Find the work done when the object moves from 4.0 to 6.u u78j8lk;fvhc ,6jbyoc5)h g0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. T ym) eafcossn fm;(d2(81jd; zhe 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 1myd)acs;s (d8zfmfn (; o2je 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 8 xgmeg736 mlfa 55-kg cart (initially at rest) across a 10 m level surface. What is the final kinetic emlg fe76x 8m3gnergy 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 moveysu /0px ec7z) a 55-kg cart (initially at rest) across a 10 m level surface. What is tsu zpx0y 7c/e)he final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. Ho g46 9chbxtz o5yzee4)w much work is required to stop t5h cgzz44eoe y)xb9 t6he 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 ad4 tz9jc(-dgf car initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same conditionjc9f- 4(zdt gd?

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 s g18 b 8cdwede6m(c8r10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm.68cd g(18ebdcsmre 8w 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 :qe (tc;yw**zpf8 kvq 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 th*vkwc*qfe y;(t z8q:pe cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, st8 +0yuvspq. n, .hdt(c nw kzkojm(e52riking the hay with a velocity of 60 m/s. It penetrates a(v.c n5z.nypjuk2h,e ms 0d8wotk+ q( 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 r 7j4q2)av imla height of 7.00 m above a floor to a height of 137iv j 4rma)l2q.0 m above the floor. 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 long7cb-.rbj ttav1 ;zg o:kuy.e9 and rises 2.0a1.ytgbk-:vezc ju t ;.b7r9 o m. 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 spring, causes the spring to s gjv u+g **tn0dt6r-yhtretch 2.0 cm. What is the spring g+-uj v6r dhn 0tt*gy*constant?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 Nhoyfv 36w bt3//m. How much potential energy does it store, when stretcho wfybtv/63h3ed 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 compresec:z,fsr9dbt9*j/6fy dd y 6ya5.sg os an initially uncompressed spring with a spring cgy9f9yz yr:fej,sd.6/*tb 5sdad6oconstant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring c5+tm lpwus*+bb2-mkv onstant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x = 0mp l2+kbs-5 *vtbumw+.)

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 7zju m(fm3 )lhof 15 N/m is initially compressed by 3.0 cm. How much work is required to comprmm f73j)lh(uz ess 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. Wha(8n9phdui*ameb qf; o10hrh)t is the speed of the slier on reaching the botto*hirnu m (1 )hpbedf09oaq8;hm 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 ks nv6z5o ;ufs8g, pushes off the top of a hill with an initial speed of 4.0 m/s. Negle5;vun6 ossf8z cting 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 ovg9q*f+3 xv7jbk d8;j1easwfrictionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the ver*jsof3g;7jq1xbe kv89 dv+awtical 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 the floor, its 4fclwor-qh3+pym 0 n8potential energy exactly equals its kinetic energy. How ffy8qh4w o lpr3nm-+ c0ast 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, blaway3a2r3 i3h ksts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, itsk3 3rahawyi32 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 leavg+8*p oyiyefmt /j4m.es the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy ij+ /po.yeigy *f tm48ms 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 at a point 45 m above the bott)ln*maa,m20m)m f o+jarfr t3om of a dip (See Ff*mlamr+3) 2raj0am mtf)no ,ig. 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. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m above the bottom fsqf3c5:j4 enbzm8 k6 of a dip (See Fig. 6-2). Neglect friction, what wkj :fbq 354e z6m8csfnill 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 above the 7 ngm+m. 0kucngo(q pw+;fa*vs+o+rf 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, wa +sfn*gg7 m+v nwf +.cqkp+oor0mu ;(hich 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 abw kr h+*uh43of 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 pendulum of length 50 cm is pulled 30 cm away from the vertical axis andjv0bfj5t jo-w 4/ys0fkop5 a,/-zgx r released frokzo - jpxrffob,t0j05y4ag/-w vj /5sm rest. What 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 uncomprw* -oxm,s;g)rs7ad vg essed horizontal spring with sprina7 msgr- ) *owxs;dv,gg 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, slows down herj*gm 85e9;ro-do hd qa 2000 kg car to stop for a red light. What work is done by the friction force against the wheelo-5 eddm89joa* h r;gqs?

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 a hori or3mgl.mb ,t3c6fnyfo03 v (kzontal surface is 50.0tof ,3(l3fy co3m6n rk 0gv.mb N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J of kinetic e5i5u/ scam;/7pi e)kqx0 uken nergy. u5 x7/ ;menai/quck)k ie0sp5 The friction force on 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-kg mass on a lo xvoixc4j2brx6) 6h0evel surface. The coefficievh0c jb 4x6) xor6xio2nt 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 in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from th/q73vbjk avw+8u ihg8e top of a 50-m high slope. If the work done bvgbv38i hqu+78 /k ajwy 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 planomd+et)dyyth7 +;p /q e is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the bp dme yq7d)hyt/++ to;ox to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is rel4*hiyc c uqxxs .h3-b5eased from rest at the top of a plane inclined at 20e above horizontabh4xy.ch 3 is-x* ucq5l. 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 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 he2:j1.xuozu 0df q g*/mtj/wg qight of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air fricgd tg./mzfu2uxj/joq: q* 1 w0tion 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 whentyta- t40irf+t54vxg he runs up a flight of stairs 10 05g vr4tt-y4+itfax t.0-m high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity of 5.0 rjpx(qcz7c.6 if. 6spm/s. Whatj rxcqp7 .p fcsi6z6.( power must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motm,lvl3y ,f +cbfx7+hror that runs for 1.0 hr? (1 hp = 746,vyrf+m,lb7h f+ l x3c W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. How much fordr )gzr)8opqhl*x k1xz.r t;8ce does her fop x8z*1rok qx.hzgrd))8 l;trot push with when she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/ l0 kexocy)-9*p /sonvs in 7.0 s. What is the average power deliv0 v y9koc-s*pxl)e/o nered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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