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

1#

What is the correct unit of work emgdqv8+j fm1 7xpressed 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 fql2nc /p+7vtno 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 ag. 6jge+ ttqn19m26gyy xv/xjsahdz8* ainst a stationary brick wall, the amount of work you zgthx /x dna* gj6myste.619 jy qv82+do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held there. xg ht r929bbz9 How much work is being done ihb9gtb29 xr9zn 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 horizontally* irym8.kls)g forward at a constant velocity carrying a 10-N object, the amount of work you dml *i8rys.k g)o 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 ve5 pah e0sj,(aaqdw5+ wrtically 3.0 m then returned to its original position. If the total weight is 30 N, how much work was don5se, wdaa5w0(hqpa j+e?

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 object do work on the objecvec+z.ibn 1+0puz 9 spt?

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.d 2 .eq a; jyk3tz8ugocc51+uv Compare the sign of the work done by gravity while the ball goes qgv;c8z.d 3 juuoy51e a+ckt2up 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 curvego03k4 :8 r/o -ocbzxjp/so iz ;tcv-f, on a Force versus position (F vs. x) graph, representss/j/ i ocv3p-o;8f-4b 0 grzcoko:tz x

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 represe; k sb)rgafk hz,klk3vc.w34m,c; w:nnts the work done by the force .m ):;l3k4a r,;b3khkzf v c,wskngwcF?

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 object's kinetic enercwv9gdz ;a* 0 .,iaeolgy

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 thez71k: t1b:uiqdu;fo qg03rvkdg, az* 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 zeroqxs-w3htgy ra .35 f6e, 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 b1hurr/exfa6 e5 b53rcar, and is moving at twice the speed of the car. Which staa6b ru/r e15brhxf3e5 tement is true about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of: tf/.5z juyca car K. The kinett .c a:5/ujfzyic energy 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 its original speb t(6inb5j ;lved. What is the ratio oj;(bn6i5 b vltf 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 is m/e1f6agwi -i,g4 loac oving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the rati 1ailfge- c6wg/,i4aoo 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 2jg*z pa rjt2i)x-6:8jdp9trxl zg )u7 .0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encou x jgzg6:rxti )dpru za-j2j*l79)p8tnter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and ski4n. 2)8hak9 /7g k i4i,wkrjjcv alic ua9cxl5d a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditi2i4hvx) ic7lacg/ 9nj a 9.8cu rjkak4kl w,i5ons?

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 Sok)v3bymaa 0 glv55fkx/2q +fun in an elliptical orbit. Neglecting any friction effects,a2mf5fq0y v) 3kb+ao kxg5lv / what 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 prin gan)47cpu)+mv*7ou) tj zirnciple.

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 potentipkvv2hoi.16 nvyq d-/ al 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 ground. A second objeac(xmet8tlwo/ -0 y7 nib:.rw ct with four times the mass of the first if released from the same height. The potential8rw w0 :m .xeoc/yt-(t 7abnil 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 nt0m.5*qc8jqlo6(mth oy5a l it to stretch 5.0 cm. If an5t(mhj a0lc ytql*oomn68 5.qother 0.200-kg mass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a sy*cr2wdo;7 6 86cyc wpf9wbr io.ewadb p/y4 o(stem

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 3t tkaigaka3la .a(2 1energy K, to its potential ener13l3aa i.a2kakag t(tgy U.

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 carggpn+z msxf 19puf81 - driving 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 very3(5 (yv4hoqq7anbtbd aah 8* t heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater hei3 5dha(b8ntvh(tq*aa q yb 74oght?

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 1 pjjkhm6 p)/rabz (2t$m_{1}$ 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 o+yv)ymi v:dla;baaa613c0sz)vo*s n f conservation of mechanical energy for conservative forces v o;3:m)0sz vdan6ca+ y *lyavias)b1.

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, hxvp /3* jdvj*g 9m(e olj*9tythrough the air (air friction is present), to the ground below. How does(* tjx/ do*jy*g99h3lpv vjme the kinetic energy (K) just before striking 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 energy. Do nw:l: ue9h *f.v pva75ggr+vgi.v k5ij7- t tzjot ignore air resistance. How much gravitational7i tgg.5+k h5vlv7t r z*:aewv:-piju gj.v9 f 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 po* f;:*.g g mons+sgzhltential energy. Do not ignore air resistance. gg:n s m*h;o. f+sglz* 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 conservatiaqu8dcl 3+)r lon 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 iscr(l: 7/gs i tz5za:ua4gb z0m

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 unitc63km8 a ,bhjc-y 3+jzh3 zllh of power expressed in SI units?

A. $kg m/s^2$

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

C. $kg m^{2}/s^3$

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit13op l-gi-s m*jwl4 mb 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 worl2:b6 gjne,fxle r0a*k in one-third the time. To do so, your power output must hfe:6,aenlxrgl2b0 *jave been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, the car's engi3.ppxom kuu ez4db 5)3ne 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 thztly6vk7i+ng/r o7 9 fere. If the object weighs 90 N, how much work was done in lifting 7lo7r9fik 6 zy/g+vntit?

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 dist -fvpu3cob; 8y*xwux :ance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight ofv ;3uf wuoyp- xcb8x:* 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 wixj+d ,w98gtn/zx k ,heth a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 5500e+ z nj8h,dx,9tx/ wkg 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 upwardlmf,7zg,( xf k6pp cf ,os08pb with a constant force of 5500 N for a distance of 50.0 m. What is the work done by thofz60p(fb 7ls m8fx,,g c pp,ke 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 ofe-)xovm)g6,h e-ix x +h) mjgq 5500 N for a distance of 50.0 m. What is the net work done on) m)q-vjg6e ihm exo,gh)+-xx 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 6.0lg/7lrxjwizg,).,d2vnw pb; 8j*3,bpuyz zh 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 fruit slides 8.0 m down a ramp, inclined ar9- zic,d /ngat $30^{\circ}$ 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 surfac 979x: qm-( dimiyq4zpvs ,cnle (assume no friction), with a force of 60.0 N at an angle om syq lm,4:(q7zicp9vixn9- df $37^{\circ}$ 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. q 46/omhyn1jj xuf59c 6-1 shows the force versus the object's position. Find the work done when the obje uyxmhf1jc94j 65/noqct 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 tl5f8j c/n i(aahe force. The graph in Fig. 6-1 shows the force versus the object's position. Finda8 a(5cnf/ji l 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. wn9mo f*)r. pu The graph in Fig. 6-1 shows the force versus the object's pw *9umprfn.)oosition. 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 in Fiqot 28uk h76afg. 6-1 shows theo2q78a u khf6t force versus the object's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied tn6gx0lcg 7tla,(7hcto move a 55-kg cart (initially at rest) across a 10 m level surface. Whhccl7t70g(x,a g l n6tat is the final kinetic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at rjsxj + if4g8;aest) across a 10 m level surface. What is th4xi js8afj+g; e 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.o/iejhh79 o w5s2jv q50 m/s. How much work is required to stop the s9i55 7ehj/o o2vjhwq mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance xkd9b2mn3*3dq u*wq.469i yti nczao is requiredqq u*2i*nb4o9td i 3zykm 9d6. c3wnax to stop a car 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-g dart. It isu9 -c)l6:tc uw5js.2u kqntf m cocked by exerting a force of 20 N over a distance of -n5u sufkmlu9wcj :).t 26 tqc5.0 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 a w j *t3*ab6v7nfnn38thk+wqand a vertical component of 60 N. T6 kn 8 7ava*qbwtjft3nh3n*+whe force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final 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 va,53c+j dusz into a bale of hay, striking the hay with a veloci vau+c3zsj,5 dty of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to a height99mo9ge (i: par cn4,xvjt,ycxtz 7*j of 13.0 m above the floor. What is the change in gravitationmox4yg r x 9c:99vezcj*tt(7j,n ,apial 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 long and rises 2jzzy- 3c9m* 7 er hp,rc6gya2zufd*-c .0 m. If the plane is,rzcm2 6g-*zru3*cpf ych z7 yejd 9a- frictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spl8. bsp+:t estring, causes the spring to stretch 2.0 cm. What is the spring. ss8bt pelt:+ 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 characterize8fb*dn3n.a pl9.b t syd by a spring constant of 60 N/m. How much potential energy does it store,a.slny*p 8t 9b.nbfd3 when stretched by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initr4m6bh amjsnk+ (br9a -,u2( fz dyp,cially uncompressed spring with a spring constant of 25 N/m by 10 a,6kr b 2nud+b4j,zarmpyh -m9sc((f 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 stretchtk a6.btcdy+. a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstttdyk .bc+6.a retched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/myj((3wfi rnn( is initially compressed by 3.0 cm. How much work is required to compress the spring an adwn(nr( f3yij (ditional 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 frji) 3c:ok3g bbom rest from the top of a 50-m high slope. What is the speed of the slier g)3cbikb o3:jon reaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with anu,)a rnuiz;u3 t)iv q2 initial speed of 4.3z tu vu)qi2,nu;)ria 0 m/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 boty pd wifj 5sb2pmj1.mr2(kf4; tom, it has a speed of 9.80 m/s. What is the vertical height of the plane?pf4d 2mrk( pi2j; jwb5fy. m1s

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 (9lu m.fh 4iaqrkcv;s n.j;t/, its potential e/;u .c.t;la j4 h msrnvik(q9fnergy exactly equals 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 from ground lerob33e ;vy,4xp rfc;a vel with a kinetic energy of 40 J. At the exact top oxbfrpv; ra3e43 yo,;cf 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 leaves the ground with a kinetic energy of 220 J. At ttpyztb6 fd35);lc af,q 79iwl he highest point in its trajectory, its kintwq,lc69 dfa 3t57zlyb ;f )ipetic 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 bottom of;g0e0f nq;bc2rzq 2b4 4 exoxa a dip (See Fig. 6-2). N4qeox;br 0bf0;c2 xag 4z 2eqneglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster start ..i05zvs 3 hpyntvi,is with a speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the di is.vz.5t ni0hvp3 yi,p?

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 starum*wy3d.8bx-k 5 u (murdafy 3ts at a point 30 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the ry3 uk*- 5ydm(a8 fdmu .b3xwuroller 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 b 0(w xe g7pjoe t:8c4 mn(rhqe2k0jr4jb0tse6all 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 i jd4q(vju qf,7s pulled 30 cm away from the vertical axis and released fro,qqdf v74uj j(m 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 horizonhg+ukm0dm9/ e tal spring with spring codemg/k+h9 m u0nstant 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 20000h+ ibw .w7dzk kg car to stop for a red light. Wk dw7z0.i+bhw hat 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 lg*edh;8hqkg g,65o y object and a horizontal surface is 50.0 N. If the initial speqg,k8; o*g6ly ehd5g hed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface.d309 3let)fi3dkzn j oskddue5vp/2 5 It has 24 J of kinetic energy. The friction force on it is a constant 0.505kf po0 /)3v9ikuz s2djd53dtdnle e 3 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level su :npuftqy* g1/rface. 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 kinetif tg/1u qny:p*c 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 theyf68g.kq6h a:b , zzlp top of a 50-m high slope. If the work done bb :a8k6q,y6lh fz. gpzy friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is(zon0orpb cn hsc 97v5b5a8sl65vxt0 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magb5nvsxo5po7c5azrls8t0 9 hb( nc 6v0nitude 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 ofdo6.qwueet0 f ,w gzrl: b7e+i9ob3mgx0nd64 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 sliuwqe z9e,ot 6mdg6:r0lw3o.g7 dbe4x+f0b inding 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 hvh3fwngaja *skcx *c ,dm5.1; eight of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air frin,.f 5v*gjch1d x*mc;aka ws3ction 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 bocrrv- h9+: q+7rfrz wcy using energy when he runs up a flight of stairs 10.0-: rc+r7h9rzq-wv+ f rcm high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity fu 44b*h5w*q f3jpdyqof 5.0 m/s. What power must be delivered to the object by hjf py*d5u4w 3fq*4bqthe 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 **ste hf1hati a4; w0 l+c5u ri++otgg1.0 hr? (1 hp = 746 h +wou+ a4s;+e0gcg a lfhir*1t 5t*itW)

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 nx -n8hciebj oo0wj,2: ev:-gwl x,:xrate of 500 W while riding. How much force does her foot push with when she is traveling at 8.0 m/bxxh:i,gove-e:n2cj :-08xlww o ,j n 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 g+ l 3k ndn 0koj1 ;-n+ymkxbiwv4sa4 vcb854ks. What is the average power delivered by the e ok wndi4nl-nvsj4y 5vk+0 a kk+bb4c83mg1; xngine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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