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

1#

What is the correct unit of work expjy paslm1 5z4 8e0jkz/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 nbq(bp2 jn3u1jo 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 brick wall, the amount of work up ng w)jo;e.2.alfu/4req6fyou doauufn ojr. lg 24)/6.w;pfq ee

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 i ,k f42p k)y jtjpalvgz88/eq6s being held there. How much work is being doga,lfp j8t y62k jk/e zq48v)pne 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 horizontalsl b 35 (f:y)psiczsn.ly forward at a constant velocity carrying a 10-N object, the amopiy5s:zcln.fs) 3 (sbunt of work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted ver (rolr/0p.h9a) zruwutically 3.0 m then returned to its original positionzlp)u. 0w(9 uoah/r rr. 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 actinjdc4)7 t;j; o bomr*cy*lk7kcg 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. Compare the sign of the w3qg-rec;f7hchq)c* z: k1 ccb ork done by gravity while the fq;r-ge: *zhq7b1cc hc c)c 3kball 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 curve, on a Force versus position (t -g(: y*n+jlwg1 ejmiF vs. x) graph, representstwj(* en-jy1+igmgl:

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 doneuan *( mw1//1 mqkosperm2p 3o by the(ro 1mq /unpa21*e mkp/smow3 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 p /7 it2 nyv29c3fpai4yu,kfwdositive, 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 object's kinetic 8 r,cfmy4o1gqa wo)p;d s d6-)qv *nkgenergy

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)9k7q ug1 cnyv 8skrx:2 *)vskar2s elqz( i3q 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 of t0m y ouqn3z 5icvg35(ahe car. Which statement is true about the truck's kinetic energy compared to that ogo i3m3q van(uc055zyf the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of car Kc7;thncu d 77gca+le bltg,4 4. The kinetic energggb,cna4c 7ht 7t7l;d leuc 4+y of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of itf7z0a8l de vx7*v3sj us original speed. What is the ra77s*3lu0aez v8xdfvj tio 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 of 3 m/s and a pebble +r fjbl(/stf6m v94xgis moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio 9 6g +(bfjvx/fmstr4lof 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 movi t*4 j(dhbyn13tcohza yjo1))7clwc19hi xl 0ng with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distancezjj l7h)y 90 nd 3(tyt hh111ci)cboa*wloxc4 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 cct(jy )j znm2bfk*i :.*nd lj:ar in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distancm:n. z)t (yb:j jd*2cjkni lf*e 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 ov ( hq 9s.wgynuu9i95vs+.wrcrbits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic eneucwv9qg5s u99nyr.hiv( + . swrgy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principle.wy q3t(97yp2 czp7* g,wwgy pb

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 ha5.n+ghbz8 jdrie-ipr ra5(s 6 ve 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 height h above the grolc8a s0v:e ) j74 l*th/jjfahound. A second object with four times the mass of the first if released from the same height. The potenti llsa/o*h tf j4 a):ve7hj8cj0al 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 caguoi/h1n ; 5)hk 9 atj3fu2bvzuses it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring 5t92kj gh f1/u3zhnibv oa;u )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 f gi5q;hjem +hbrzxn ,5+(cd/energy 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,tzk*(1 g )isgt to its potential energy Utsk1 i()zgt *g.

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 drivingnaco: (9ci3 a;pchuxv,z suk p)gg1;( up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy osc/,ud 2is pu1bject are sliding with equal speeds along /sc1p isudu,2a level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater height?

A. The heavy object, because it has greater kinetic energy.

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses jz5tx hez3(xsa- (7qb $m_{1}$ 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 conservatia z68n l1mec4bon of mechanical energy for conservative forces4cazm 81l be6n.

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 ;1m.nqt/y zlo p(t v;l k2chb9a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the hotc;/yv9.lnqzlp b t;mk(2 1 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 ene8kd;j(ojc6k imnr z1l )2c3si rgy. Do not ignore air resistance. How much gravit6; 2csmik j8oji n3rcdl( k1z)ational 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 pote 5f le*s53 + kkqo)u1xov1 yxlp2f3okjntial energy. Do u s*olqej5v11flk)of3 pxx2 ko+5ky3 not ignore air resistance. 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 (y6 8vir hdof7energy.

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 isqy5;ixypxgmi vf 70+)ni-6ei

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 expc 8b0 v0( .ptu x rfkjua;2wp1iqvpc7;ressed 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, wh0jyry gsy (4e:ich 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 in one-third tsf0 f4a-yp+)hyk:zss he time. To do so, your power output must have):+ ya4kysfsfpzs -h0 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 acce 7,h5v4wvw2mu niyl8qleration, 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 iu i / zb61vp8z0rnt8rm and held there. If the object weighs 90 N, how much work was done r tri1z60b/ vzi8n8pu 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 constant ve 9xsv esu21h) .i 0lk8g.3h.ilepb vrn6x hzl)locity of 0.50 m/s. What)s. 3) 8 nzhvp60e.lux b2elhxvi.hg rl9is1 k 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 constb4je +q 33zq 19oozouqant force of 5500 N for a distance of 50.0 m. What is the work doq1b q 3u oz4ozqjo+3e9ne 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 a constant force of 5500 N for a distacr85zbmg- wd);7t ig (0 regcbnce of 50.0 m. What is the work done by the weight o(z0 )gim 5 8wr;dgc-rct7ebgbf 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 pulle fip5hpbd1wa3: -l fa5d upward with a constant force of 5500 N for a distance of 50.0 m. What is 1d 5bf3i wp:hfaapl5- 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 6h3 rk( ;jdhhd-.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 frult fx 7;j3gr*(*t 6tfbvkfyr (it 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 Safnyln4/ccwd 5t524 kw rah in a sled on an icy surface (assume no friction), with a force of t5k5/w2 w4dcyncl 4fn60.0 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 t3(u h .y7chvpp +/fa8f-ztprgraph in Fig. 6-1 shows the force versus the object's position. Find r8ztpv(ah +cu.3ht7-pf /yfpthe 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 graphw*sj)e:wj0,/6vvrc jo orq26 kws)ba in Fig. 6-1 sho6o6rb:v0)ws,wvck ja*q/w esjjo)2rws 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 *.e;qz3ca- vlvpt+c sFig. 6-1 shows the force se.-*zpl vqv;ca tc+3 versus the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph injwlk7o n53 rk i,q(gm7 Fig. 6-1 shows the force versus the object's position. Find the work done when the object j57o3,nrlkkwig 7q m(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 res0f2 4t qluc *tcivluh(3b9twa 7.zqg* s9w4jd t) ac( wcq4hi*c.lluud ftbq ttgjv9a34* 9 s02wz7ross a 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 4 yfb 4k/zuy4d200 N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface. What is tyk4 y4/zd u4fbhe 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 iv1r.k/ld k-z m/s. How much work is required to stop the massk 1-lkdi/zv r.?

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 x -dmmyejv2 k5j 3)z/wdistance is required to stop a car moving at 50 m/s under the same conditi3wmjexkmv/ -) y 5jz2don?

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 10-g dart. :2t;d9k 1nyqrfj6rj rIt is cocked by exerting a force of tfrjkd19q2; 6 n:jrry 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a vertical component of 60 g8ke juw57+ vnN. The force is applied to a box which rests on a level frictionless floor. The cart starts f wgn8u5 jkve+7rom rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot h yl-gpat4ki;v hx2jb/5o 5r(e orizontally 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 ac;a(5b4h k/ey5i vrt2lpj gx o-ting 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 v5axc3rq7h 67i eipg, r( *xrp7.00 m above a floor to a height of 13.0 m above the floor. What is t pv* 5 7xg7rah,ir(6iepcqr3x he 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.; iw9xszqz-ilf2 78 ev qqkv8 long and rises 2.0 m. If the plane is frictionless, how much work was.ie kiz8qwx-7lfs ; q9q8v2vz 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 sp-1d dep2 z)s.-w ahk:2xb qrwyring to stretch 2.0 cm. What is the spring q-b2k adhwy2x d-1s.)wezpr: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 b 0r ks,v(luvwj:i e58oy a spring constant of 60 N/m. How much potential energy does it store, when stree5,lj 0(8i svukr:ow vtched 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 a(vsi+ju9x+b, ow g 7gen initially uncompressed spring with a 9,u ggv+ sowb7jxe(+ispring constant 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 constanvg5itzrcm(4x.t 9b (ck;x 5.fya4m3 byy+ mnot 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x =;9 grbtkf5ixx+ 4cm .(.y4mmyavn(btz yco53 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 compressedl:p ung mv9m1* by 3.0 cm. How much work is required to compres v*gmln mp9:u1s 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 s6tlrnpa. *-tqll1rio9; z 1nhlope. What is the speed of the slier on reaching the bottom of the *zh61alq.lorpn- r lt; 1it9nslope? (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 0)mrlyw k gg h9s*z+o83(mz f8fhi:pfwith an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after drorzlf:gm*0 +hf9g)(s i zpy83mfw8kho pping 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 fricti8 nwb))r ox5uqonless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the verticaru)5x bon)q 8wl 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 0z q4t-rjkt;b5 .70 m above the floor, its potential energy exactly equals its kinetic4tj r-;kqzt5b 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 ground level with a ky,-:g po5xs edudt tdyj32 6j9inetic energy of 40 J. Agt-d3sj6 odu2 9xt,5 y ed:ypjt 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 leave1x 58gxrz d mobp,:/cqs the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical heighrg,c1xd:qpm5boz x8/t, 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 bottom of a di am ht;fs2ns)av1 5/wb66pfvsp (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 anmtfv1abp26f/h) 6 s5;sa swvbove 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 poin6 hrk wa,,q9dy /tbqc6t 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the rollehqkr/dqt bw696y c,,ar 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 nw58uhba74mp30 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2)abw5 4 upnm78h. 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 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 z j b+1 0 luijoxg(cait,+.j r5qxz*k6speed 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 pendulum of length 50 cm is pulled 30 cm awayxk.6zv86 qnm u from the vertical axis and released from rest. What will be its speed at the bottomv6m 6uk .qx8nz 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 hr *u)hxc4o t.iits an initially uncompressed horizontal spring with sprc*ituo .4)h rxing 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, slows0ykt+c. /bvxf down her 2000 kg car to stop for a red light. What work is done by the friction force aga/0fyvt . +bxkcinst 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 a horizontal surfx- vv1n(flc yfe5vi/7l tu i38ace is 50.0 N. If the initial speed of the object is 25.0 m/ xn7f1yt vul38(vv-cief5 li/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 surfacgj3u((.+ipz0rl xt b rq7 ,acxe. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far will it slqr,r0l b 37j( +tcpz(.i gaxuxide?

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 tjqj3tp 0na; 2mass on a level surface. The coefficieat2n jj pq3t0;nt 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 frlfqe09jrr;s 1 uu:sb5om rest from the top of a 50-m high slope. If the work done by friction is0b59;fls1uj srr:qu e $-6.0 \times 10^{3} \; J$, 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 mamx j141o vpz5 long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was tmx4a 1poz51jvhe magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the ta( hy( jt,hqles0+e xly,4pj-op 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 y+j( l,h l(j -etxeph4 qysa0,4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikes t- fzgj aa/qh,6he ground with a velocity of 7.00 m/s. Whazgqhj aa-6,/ ft average force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs (yv 0q,3se-.txnodyeby i +b/ up a flight of stairs 10.0-m high, ,by0 sdi+yy/no3qt-( e xbve.in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity of 5.0 m/s. W8mdv8q0 mt 6fvv(+shl hat power must be delivered to the odst 6 8+vlv8 mhq(mf0vbject 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 by2sj,pdb/q 8 fbi(g2l e a 1.0 hp motor that runs for 1.0 hr? (1 hp = 2q(sp8jbg dbei /2 l,f746 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 force detd, +n)l5cn loes her foot push with when she is travelingnlt,5)cn +del 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 the average pogd d(s-oanw 7u,2 vh3osc ; :8o*kzgvwwer delivered by the engine? (1 hp = 746 v -( wzo83 ad2s*v:w7sdo ;ugkgch,o nW)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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