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

1#

What is the correct /nv z ds.nv+vb)f uq5t+khc* 9unit of work expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no mot(d :am1 i6bskw,0jiyoion?

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 stationar2h2uw e(o(r)p5 jpnl iy brick wall, the amount of work you dolouhi 2 (5(pjre pnw)2

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held the vwt35k ftw5+3.ngphy re. How much work is being done in holding+ h y3.vpgnkt5ftw w53 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 horion./s +vu;wg gzontally forward at a constant velocity carrying a 10-N objectg.s+/wunv o; g, the 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 vertically 3.0 m then return0ubq:*pca j:eed to its original position. If the total weight is 30 N, how much work was done?0 p*::ejqcuba

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 actinzh ky:k6c8bpdc*) 5x*on+felg 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 work done by gravity w 7f/d9lb da2mq3r*mri smkm81hile the ball goes up with the sign of the work done by gravity while it goeql2fm3 1asdm97 b kr/rmm8 i*ds 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 veffpsd : qrq8 ((2 w5din2tdi7g/uv fo7rsus position (F vs. x) graph, representsq7g(8 wv25fd rdi2fq7diu (sp o: /tfn

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), wh kamx+/j3yfl 7at represents the work done by the fjy3/x+lm f7 kaorce F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the objecty .adowjf (o659p+ yzyf dnx; 42yt2it'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 thep f2 o8/tycrwd vj9.bu3 6vb:q 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 k7+,kr: mfzy denergy

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 s bpr39m* j+ntcpeed of the car. Which statement is true about the truck's kinetic energy compared to that ofn9tp3rbjm c*+ 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 K.:ll3nvdwd* 5n*( uwpq The kinetic energn5d* 3* uvlw wp:qd(lny 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 tz wtwet1,y:4t;: krghalf of its original speed. What is the ratio of the final kinetic energy r,ztywkt t:w;g 1: 4teto 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 an9z4 ( pc)fg2nrewx1+ 0fm aistd a pebble is moving at a speed of 5 m/s. If both objects has4atxmc 1g )0(2p9i fzwr f+enve the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed3wqk2fe,m nc rc3)zi. 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter f33.kqinw2z,crec )mthe same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car w)tci5 dkc09w86 emgidf7t.)q de1 uiin a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under th. )wdedcudiw7f 5i c6qig8t t90k) em1e 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 4 loo35tecphm.l;b c.dwis9d w41 /zhSun in an elliptical orbit. Neglecting any friction effects, what happens to tho zb;htci 5dwl34/.mch9.o 1pw4edsle 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 pc5) 3 zxl9unodrinciple.

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 t:h3hv gr9mhm3(iozrf ( 22ez ro have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the j+,iecxvv uy:d,dwck,.vaw0 . u:2c qground. A second object with four times the mass of the first if releaj u+:x:.w y.dadckie0,2v, uwvq,c cvsed 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 z8/+uwz u 3 sk1qfpr-dstretch 5.0 cm. If another 0.200-kg mass is added to the sqzkd +3-1ups r f8uzw/pring, 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+:+mtjjm 7hae:/u e xz of a system

A. is equally divided between kinetic energy and potential energy.

B. is either all kinetic energy or all potential energy, at any one instant.

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to its potentipq4(byp*tt i( al energy bt(t*(qiy pp4U.

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 drivingw5pld1v1dr**. f-h:k crbj mm 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 sliding with equal speeds alongkll:z: 3er2s0-x1f sm b-m( 3vndtbjg a leln-(rm0 ve :jb2sf3s-k :dgb1xmtl 3zvel 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 /qmg j0 -e4ig* ,qsh yu/ti1br$m_{1}$ 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 energ5j6a b+8zugki y for conservative forces.bzg +5u 8ika6j

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 air (air frictioa/y ;9k3v00qigib n ipn is present), to the ground below. How does the kinetic energy (K) just before strn 3;g0iaik/9 v0yb ipqiking 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 energybm 3x)j+ xrkc08bej-u . Do not ignore air resistance. How much gravitatio xc83mejj +)bubx k0-rnal 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 gravitatz.; dhxf1*oaoional potential energy. Do not ignore air resistance. How much ki;zd*x fa1oho. netic 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 conserva(*wu)e f3(auice:gcq tion 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 isay0r **kl6 :x.p,c yci:eujto

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power expressed i66fcf z)k j5tgn 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:*dlzwfev *fr*p;r l9 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-hl:*b +p5xo9s u fnsf one-third the time. To do so, your power output must have bus ofn9xhl-bp+s 5:f*een

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 )+f7qne wg0oxcf x m73constant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertics5jgtp;glht 9w 4g; 6 iommpbo)qt/k ix+:x69ally 2.0 m and held there. If the object weighs 90 N, how muc:ohk+6lw pt6xxbg /o);p9;9gmsm itig5qj 4t h 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 up79f+s p*leard in the air a distance of 1.0 m, at a constant velocpd+el9sf 7 a*rity of 0.50 m/s. 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 witho6om3 o ,fg4cm a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 5504mgo,mc6f 3o o0 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 tx- 7yh-lquf*constant force of 5500 N for a distance of 50.0 m. What is the work done byuh*ftq7 -y-x l the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 Nx0 mnavpg9f )vysbj0+m ,f+*p9io8k j for a distance of 50.0 m. What is the net work donsgbkvj0fx09,m)p8j9vo+ y af m+np* ie 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 :o + :h up3nri9gcxt6pup along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp,kv/fei10 u7y6 cefnq8 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 * zg9uj8pp7hdod 42cw jm:r1mSarah in a sled on an icy surface (assume no friction), with a zc 427mro pp:*dudg1 8jwmj9h 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 grap v1o qcb5;mq5qh in Fig. 6-1 shows the force versus the object's position. Find the work dom1;cqb55 q vqone 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 direct-yeys33ozgtj3 9m lk3ion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 2.0 to 4.0 m. 9gj 3y3ezlo-tm3yk s3

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 dirsw6bcc 3+h*nsection of the force. The graph in Fig. 6-1 shows the force versus the object's positioc3hn scs+6 bw*n. 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 ino34zvrq5 v h4u the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find tzor5vv43uh 4qhe 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 movep1 pps0s62eap7) sy p+bf u*c6goz*ve a 55-kg cart (initially at rest) across a 10 m level surface. What is the final ky apgv*7poz *pbe6ssp) 106+f u2ce spinetic 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 restp2dmfmsc8u-*smot6b n / b*8 j) acrossc- bu */*po6828snmsmbmjdft a 10 m level surface. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much work is requij 2w2/6p/pilwqxf7* hk s,i mdred to stop the mass/ikl2pspw *mi q2x,j7 / f6hdw?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance is gq 29zt:9 a osre .93ucjdxn+mrequired to stop a car moving at 50 m/sx: .ztg39 aqm eocrdun+29 9js 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-g dart.8jb8 vg ya;sfo6(z o,n 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 negligible massb oo8fvjy;a8,(zn6 gs?

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)v tu1zyu5sw+9gt c 3k and a vertical component of 60 N. The force is applied to a box whichk uvgwsc3 yutz) +1t59 rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final 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, striki(pji-a6 rqko9 ng the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm (6ioja-qk 9r pbefore 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 fko. q; dc7jf4: ;8 wstkfxl(6hbjiv,srom a height of 7.00 m above a floor to a height of 13.0 m above the floc8 j ,;qb6:isolkkfvh(x ; t4.wj7dfsor. 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 inuik.xt glqwt8(gby++i 8m /k:,y ,fx vclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is fr+/k gt,,i:xqgxtbmiy 8u8 yv.(w+kflictionless, 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 thelup6h9 alkb79l2xy88(x qsg c spring to stretch 2.0 cm. What is thxyl uchx9(8b a qslg7l9286kpe spring 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 N/m. Hodn.h;lg5v;p mw much potential energy does it store, when stretched by 1.0 c;gl hm5vpd n;.m?

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 init 0bq(: j72rvyfvhdfg z( hbbj:dg m:*8ially uncompressed spring with a spring constant of 25 N/m*bb hg(yfzq::g0 j(f bmv:vrj 7d d8h2 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 constant 40 N/m from j5.6fzse1/l . sd sokax = 0.20 m to 0.25 m? (Assume the unstretched position is at x =s 6d.ak e5/s.1folsjz 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 3.0 cmn3 5.u yx0pxpg. How much work is required to compyp3 .5 xnugx0press 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 fr5ijsa*8i*( s* xhckwmom rest from the top of a 50-m high slope. What is the speed of the slier on ric5*s skah*iw xm( *j8eaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial spesc 9n 4k f)13dxle9iiied of 4.0 mis9c1 ed)9n iil4f xk3/s. 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 a frictionless inclined plane. At the bottom, it has uhf hfj:ps7i) 3r*w1i a speed of 9.80 m/s. What is the vertical height of the plane3fu7h:pf)w1hrii s j* ?

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 x3 r9bv.*(rb-a) i6nu j;uysmxn 2 couabove the floor, its potential energy exactly equals its kinetinrij (uvabmx 2-9 )u*; sxy6b.nru3coc 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 wdnpg;hjf5w 78 :s38ic syt0eyith a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical e:s 3;8p tsj0ydfwge8cy 7ni5 hnergy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy of 220 J. kax o 5qot4,johok 1sx43 94ir At the highest point in o okth9 as4kir,x 14qj 3o54oxits trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the bottomujsa+ 2()d6i-yst q/sl9 cukc of a dip (See Fig. 6-2). Neglect friction, wh( - sadkc+)t lisjqs6u/y2 c9uat 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 thetx3m0wicv3i * 3c*8 q swfb5 p*jdtd q+r+i.cw bottom of a dip (See Fig. 6-2). Neglect friction, what will be the *5 tx 8 +q*mc3q pi0*idswr3tc.w v ij+cdbfw3speed 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 30e *p*tcqz8 me9iq 3p/x m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of cipq 9 *e*8zmxp/3q etthe 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 sq/lvs rvzuecvv j:/t 4:9y22 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 a*wd 9l. xdyi/pnd released from rest. 9p *.li/ydxwd 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 unc56(ulgq8b h + d fyt1f zml:amrw )6qf9li6jf)ompressed horizontal spring wit litqh +u)mgb6a )r9f6:z yffd1f85ql w l(6jmh spring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling -q mo+6rz6*2 aw rao:td+l5 g( jcchp//f cptlat 22 m/s, slows down her 2000 kg car to stop for a red light. Whp6*r daw c/pmjzl- t( q/ga lo5rtcho:++6c f2at work is done by the friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horizont,*fl4 c5if clfal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before comin*l,cf ifl5 fc4g 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 suxk)wgrlm68), vr;w;vk0jmjmy a b 4 m0rface. It has 24 J of kinetic energy. The fr)6aky4jr)mv8lw r0 w; mx0m ;,mjk bgviction 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 t/:b)++y5btnj autr 8 dp, sxwmo a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic+ ):,jbn+ rydtab/t8pusm 5w x 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 workubou0faffp:e.v s7(d2+ot8h done by friction isp d2t8o.ufv h+0e asofub7f:( $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is 4.0 m long and d ,wy.ve0w fb2rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the boxyv.e2 d,wbf 0w?

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 plane inclined at awb3 faku 70fz7c, a4o20e above horizontal. The coefficient of kinetic friction between the mass and theca7u o3,ab 0fa4fzw7k 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 height of qbr- v hey-fr)2 hfe. -e;j8kz10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average -)frj-yq-zhe; hbf8e k2. er vforce 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 u)hkkl g f2o)21v8qj;inflc9 ap a flight of stairs 10.0-m high,l92)8hiqna lkjf;go) f1v2ck 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 oh13 486hmib8donb s iebject with a constant velocity of 5.0 m/s. What power must be delivered to the object by then6biime1d8hb834o h s force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs for 1.0 heh(;j imp3cn - .kmn,yi lil.2r? (1 hp = ikmm2(n.3.;lh n,-lpjic yi e746 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 forc*kzzks0 :fm-r-.zilm 85w twxe does her foot push with when she is traveling at 8.0 m/5rik 0z msk :wm l.tzfz8*w--xs?

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 pozd lf4 xp;94vyjy0b+qnft o .,wer deliver9y4z.+ qj0nl ,odf4vtp;fxbyed by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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