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

1#

What is the correct unit of work expressed in68pc z)selq. s 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 motionai t0o17kh a(x?

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 brickvq girs 9k.)c:j(j3sj wall, the amount of work you cs s.j k9)(:rqijj gv3do

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 beingp(hgg vr/p3g 6 held there. How much workg ghpv/(63 gpr is being done in holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizonta4p) wb.:k: g sfy+yr9*qpt.qhq;lceq2nvrp0 lly forward at a constant velocity carrying a 10-N object, thes+0ytkqnv2q:l.p9)hgb rr.y;f:qw c* pe4 pq amount 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 uq*w durn5*ll;wxcb +dg3 8n0tically 3.0 m then returned to its original position. If the total weigh 83*50u+ ;r xqwdl*cwdn blngut 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 an obje ,8u c.d2yn;xs1.7lcdl 4s esxgukt6nct 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-x7wc-y qw (yev;,npj of the work done by gravity while the ; n-c qy-, xwyjve(7wpball 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 versus0h-) vb z;582w meonbu/r9,/wold a xkdwsnb; position (F vs. x) graph, represents ;,nohxdsvebd0b r5/ 9 akw-u2w) bznmwo8/l;

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 tkig9x ft /445q p 7anshp(az(de3u g/she work done by the force F?ags(9an 4qzkp(iu hd x5//e7 f4tps3g

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 donefr.,o*g e5g a5 gv m-kp2kw1hp on an object 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 negat- .um2nbj;o5jbut k n3ive, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the object's kinetic ehs-fo o4*e(t4s87 p iudj ofx)x+en(:f o,mctnergy

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 t u 3j6n1kr9nfbhe speed of the car. Which statement is true about the truck's kineti1 un 3nfr6bkj9c 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, anli qr 2/cp)jlk.zi(ui np- +)kd car J has half the mass of car K. The kinetic energy of car J, compared to car/j)lkripp) i i-lknzuc(q+2. 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 wiyt;dh zv ny44k*9k8 xeth half of its original speed. What is the ratio of the fz4etvk 9nk dh* ;yx84yinal 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 is moving at a speed of 5 m/sm38 w -nur efghon*ik0(6v *bx. If both objects have the same kinetic energy, what is th *g83ebkf *nwou6mvi0 -x (rnhe 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 mass is moving bvsw4r4 cpd,o 9ip +-mwith speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object trapr9c4+- sw mvpi,d4ob vels 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 distancem+ gg2th9k5o1w2-v xjtct + nt on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidde m-gt2+n+9tgx5vt2koj 1 tw chd, 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 mrfqn nkn7clwi781+ 0Sun in an elliptical orbit. Neglecting any friction effects, q8k0cfilw +71rn 7nmnwhat happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

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

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principle6sgfej9hn* 4p .

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 rm)jjo0dw9 d5 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 abmbj m+hm2 /(tqove the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the se/m+bjq(m mth 2cond 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 oflt .hvrvoif5 jlw +965 a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy oot 6i+vfw5rj lh.5v9lf 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 en wgs/ l 14(vb;x/pw wc:9vo,-ly sfzmsbw(1ysergy 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.6b9q wx,*c9cg9spzou Compare its kinetic energy K, to its potential energy U.9su69 b ,zogwcx*cqp9

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 drivinx:w8 xf1,xks tg 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 object are s 7(, 9nbjd4/no arij/g/ tswkhliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater hd(i/b /jjanw rh/ gto4,n9ks7eight?

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 9glcg- ;aok) i1fu s; f2e)zxp$m_{1}$ 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 envi 5ujkkl8t 748ypj- sergy for conservative forces.jlkip uj5v k-84 7y8st

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 tofad+1b)rde25 ar4yra p of a 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 thfr4a)1aa rr2b+ yd5ed e potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Do not ignoro6h rmvo,cw+396i:yv n)g tto e air resistance. How much gravitational potential energy did the ballr)3,gomych ti6 o+t6:vnv9o w 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 rce-o a)r4mwfg w)05f30 J of gravitational potential energy. Do not ignore air rewfr0g5w-)a )c4 m eorfsistance. 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 conservat: c0l rlib/gu+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 3.q5n c8+o0kn 2sp gpc)1wtlv yd4bpy

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 powet* u bto,8nfiyc 5vt+/r 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/9. u,,rseah x1kbobh 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/wk0xtf 5cpf; did 3 times the work in one-third the time. To do so, your ;wt x/5cfp0k fpower 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 acceler3abk x2 j nbqgc*5+co9ation, 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 objeo; ni,dcw:egamjq+ muh688 f* ct weighs 90 N, huaq+: m8,fw8* eo hc6ndi jmg;ow much work was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at a constant v z 1kol0q+ehh2ld*.ut3 gu 0mpxu7k3kelocity of 0.50 m/s. What is th33 1 mu x70tdkeuq*0z2+.olhluhgkk pe 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 constant force of 5500 N for a disiaxe5oosupiry /9 +7*tance of 50.0 m. What is th+i5 i eos/*7pryuxao9e 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 wit- e-o7eia)pwdh a constant force of 5500 N for a distance of 50.0 mpi-a7-)e d woe. What is the 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 (-j - mg/qgthnrfg z02 g1/k9xzi:vd ppulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the1rtg/p igg/0h9z mx-vz(2fgj kn- :qd 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 alonguo+w) fo5men7lm1 u9 apcwi 42 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 frur 8 *43smshgvz1 ongf cj-u,-jit 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 sled on an icy 0cvi;c;hcbw2jl op:h /8; iycsurface (assume no friction), with a force of 60.ic/hcwl;8c :o0;pyv2 ;jh ibc 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. 6yb.y ( e/vo-gn-1 shows the force versus the object -gn( y.obey/v'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 zmu(pu-sv(o9 graph in Fig. 6-1 shows the force versus the object's posovs(9p zm (uu-ition. 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 thi4gsrs05 z7q de direction of the force. The graph in Fig. 6-1 shows th 0zs4srqi7d 5ge force versus the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object b+:7 uhqvf6lpd vbz y* 1l;,hf;hr9lyin the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Ff+h1 7vv6 p z;qhd;yrb*yf,ll: 9ublhind 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 atkoxu qs1l8 jc*a:o8 c* rest) across a 10 m level surface. What is the fin xoju:c *l1 oq8a*8skcal kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at rr-j,xf4wd*og:dcn4k l9 p yx:est) across a 10 m level surface. What is the final speed of *4wn: dxr,- gjxl: 9fy pd4kcothe 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 required tcouce p58 bj kh7(e0n3o stop t 580 cubpjne3e 7o(khche 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 )m zssdwabr96 pt9d6 7at 25 m/s, what distance is required to stop a ca d6td96p 9mr basw7sz)r moving at 50 m/s under 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 propels a 10-gmcq;b+ v.cvj 8ph9 6uf 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 neglim hbjqu9 ;6fvv.c p8c+gible 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 co.7ot8z2 dq mvmam8nh,bmi1p 3mponent 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. Wh db28 qmia1z .vm8o3t7mmn,hp at is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hawz 2j ggjvd 3pcsy.v;q1s4e)8 xtl/a0y, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stoppiyz;)pt 0glvjqj .s4ga2 vc3x ed/1 8wsng. 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 heighy g2g) m*ql vs/+jyi;bt of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational potential ene/2) bi+lg*s yyvgqjm; rgy?

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 iak7evef ./q8. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionlveq kae7/8i .fess, 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, causek0s qdl:x6xyw10)+ n1d hpha as the spring to stretch 2.0 cm. What is the spring con ln +adyx x1qhwk1a:hsp)d00 6stant?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much potential em(5 b 6:n:jik a*i*a-d:wzw2cqiche inergy does it store, when stretched by 1.0ew dh:c-i 6icb:m:(aa z* 5i2ikqjw*n cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially unpdy(-k1f( lmc compressed spring with a s-l 1pfkcmy((d pring 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 9rycs*jd5r3vftm4n r9t 7cp/ a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at 35/p4rt*rnj9ys 7d 9fvcr tm cx = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3kalh* m )du rst;fh2y;q3p/t6.0 cm. How mu tfh s)2*phktu;ld3y6qmr a/;ch work is required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from theqopc4 ne4vct0yb /-p6 top of a 50-m high slope. What is the speed of the slier on reaching the bottom of tc-n opc0qe4tyv6 bp/ 4he 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 t(r:ajle om: +phhk3 p.mq7( uyby)th:he top of a hill with an initial speed of 4.0 m/set:l m(:kjpu:h (ra)b qyp+o3hh 7 .ym. Neglecting 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 a2ut4lpdw 80e cwhz w-8qxh. )z frictionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the uez8p)chw 02.-wwzdx ht q4l8 vertical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m above the floor,qamlhg.mpc 2,: 9as2 du -qaq) its potential energy exactly equals 2la c9sm2-hqm a:)q,udqpa g.its kinetic energy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up fdxxfi2 f74ho-vm8xdf.vr(apoy8 1d) rom ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical heigpdd )71 xfav8xd.-oi4hr2ffxo( ym 8vht does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy of 220 J. ovi0 k1iqa7;qAt the highest point in its trajectory, its kinetic en71iqqvik 0a;oergy is 120 J. To what vertical height, relative to its launch point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 ssd3dg . )gpjf;z sc:gpl mgj908j63qm above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be g d6 p 3.lgz:q9dfs s;g 3p8jcj0)sgmjthe 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 2cgp*iu sy:i j:el,+tthe bottom of a dip (See Fig. 6-2). Nplstcjgiy*+ eu: :i ,2eglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip with a specr 5 ,ori+*ies;q2/h0tiqfueed of 25 m/s (See Fig. rri,o*sfci+/e ht;q equ052 i6-2). 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 dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the r29 awfev+hr30 x-zseball 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 aw1 b *ma70r q5qdggpfwmg1vl;:ay from the vertical axis and released froqrmg;gdlv:m 1fpa *q5 wgb71 0m 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 uncompressed horizontal yf. h5 dv)b+hdgr21xl spring with spr .+)1rh gfxhyd5b vl2ding 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 her 2000 kg car to stop for a red l-qlqp i+zzn40ekmp7:al)f o)0 ;urqfight. What work is done by thn7az 4z)-pem qop)f:f0i +lrqq0;k lue 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 bsmj0+ mau5 ulh.)odq;ky 05g ketween a 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 q s0yoma jl dkuumh5+;0.k)5gm/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 od63(l pfk3 14 erdfavpf kinetic energy. The fric43pa pvk3dr(6 eff1ldtion 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 horizorf:z 7dmp.u*h9 3bv5gyam z9mntally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction betwee u y9dmg7zz5.a:9fbr3m mv*p hn 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 the top of a 50-m high slope. If the work haic :)zk9hg3(0kko,ux ndp( done by frictio9z,d) :3hnpiuak0k c og x(kh(n 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. yiw8a ; gcwguogwk7g75.8ifq)puv : *s p*/wgThe plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the pl5gvkc i ag 7wpwgiuyf :g8uq)wp*8 s/w;og *7.ane. 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 rest at the top of a 4o3h1r2 csowzm 45radh)ogauxm: 5 9dplane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What wilo5rs h)4zro d 1m5goh293c m :waua4xdl be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikes the groun1v;w3k , y rahmny076pwbq uptn/1 z2ud with a velocity of 7.00 m/s. What averageqbhu137 utn1vr/kw m,y;pan0 pw2zy6 force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a 9n7ekeojpry0n-, zc( flight of stairs 10.0-m hi9 kn70(-eocrjz pye,ngh, 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 obsg-mbp-+h*3lv)7gr gox 2 pv yject with a constant velocity of 5.0 m/s. What power must be delive h 7lv*r)xpysvbomggp2-g-+3 red 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 1.0eri/kd vf )zf/./ bv/y hp motor that runs for 1.0 hr? (1 hp = 746ed z/v/v k)/y.ffb r/i 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 ofxm)y i *0 cfnm -ny1lpg;/8ebn 500 W while riding. How much force does her footg *e-m0nx8 n lynmf) 1y/pcbi; 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/s in 7.0 s. What is ktpqo/spft5s0p5 d .tf.v01 lthe average power delivered by the engin/t05 lkd.sp0p 1 fvp5qst .fote? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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