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

1#

What is the correct unit of work expressedz j (2cv4ota.z 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 sys ez aog,o.k5o3tem if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against c;j*; /88,i-r z htjvcgempft a stationary brick wall, the amount of work you do t8j/zicr,t-gfmcvp* ; ;hje8

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 anbki+yedu7 3/fsqoi + 2d is being held there. How much work is being done in holding thei2e7doi+ysb+ q fu/k3 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 forward at a constant velocity carryice;8kp;g4 z9la+ucq dng a 10-N object, the amount of work you gld98 a;4e puz; qcc+kdo 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 rexn20 )og motfli08y:gturned to its original position. Ifyog8)xlt0:o0f m2g in the total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an ob.; 3 oi(ewig ;3y jx/qh3mxhf;ydp6hv ject 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 shw.zyjdm/)p/t 9( v wzign of the work done by gravity while the ball goes up with the sign of the work done by gravity (/p.zm d/th9) wzvywjwhile it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus posib /ba(+c v+tngtion (F vs. x) graph, representsag/++ nbtbvc(

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. xlxq k pbhf1d 8(.0r -jx-qkx9b), what represents the work done by t xbkx 90-p xlh.jk(f8b1qd-qr he force F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object's r tc+/, c)jyf*v8e /sqn kyh;skinetic 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 o *+ 4b /twcs-ozffit-a6vo+c rb8 e:vcbject is negative, 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 0n1sw+vytx1 bypsn ksgt,s5r l8;5.hthe object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twia,-f(qo: sj- z1vlyowce the speed of the c: sy ojo,az-wqfv (-l1ar. Which statement 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 car K. ,t:u ,c8f.6qifar/co hzry s;The kinetic energy yrc 6/z8a :c,tuh iqfro; .,fsof 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 o sig,,r7 ufol0)w edw*-g7 peyf its original speed. What is the ratio of the final kinetic energy to the initial kinetils7 wgf)e0gd*u ,7,ypwi reo -c 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;l * 7up+1uju3 h0o8jsgwr rnz 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to tjzrlo jsw;uhg *+r 1 u083p7nuhe 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 k ccuqy4 :m(0.vpi/pe awxe9 :mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, an iy( euweaqcpp:v/.xk9 40m:cd 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 skid a certain dh p8yi1l2wwps v3h* 7vistance on a straight, level road. If you had been traveling twice as fast, what dista*31vw p lspwv2hy8 ih7nce would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits tg1m/ ,dsv(l0vhlc*dn he Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic energy?nd,sv1m(lc0l*h / vg d

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-energyvq p.(8ubjq: : gg)luq principle.

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; l* e qfvkd.aci:tz7 b(3;lql 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 hzsss*-,c1yew9l uvb3 e;w :f h above the ground. A second object with four times the mass of the first if released from the same height. The potential energyw ;s,fzue * :sv1hbl we9cs-y3 of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it to stretch 5.0 cm. I**ul t7/j)k qapf.uei)k+czaf another 0.200-kg mass is added to the spring, the potential energy of thz+u tfe)kk 7.*apjc/ laui)q*e 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 endgap d::od z05/fcjbnpy(: a+ ergy 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. Compayj1lkd j/s27i5k2p a 7(sircjtwz 8b.re its kinetic energy K, to its potential energyzlr(7 5ipisk kbcsjj8a.jdt 21y /27w 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 car dri v,vweo(zym)h /zy,y-jwm1c: 0w b3voving 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 scu; n1-jld,i and a very 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 heigd -i;jnc1lus, ht?

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 i4..8rq q+()4 xgtvzlclwnx r$m_{1}$ 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 me3 pn/y,g2izx q0 j)dfechanical energy for conservative forces)3xg/,zf 0e2ipjyqdn.

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 buildink vo) so)q*kw4g, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground co4sq )*o )kkwvompare 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 gains0 najsf:c4qvu3 n0fl4 30 J of kinetic energy. Do not ignore air resistance. How much gravitat 4c4lvf3j:suqafn0 0nional 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 pwtfg f n(i gz6:.l+nv;7y.mre2+ mbruotential energy. Do not ignore air resistance. How mu7 gue+bnvn+fi m(6. rmglf y2 wr;t.z:ch 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 conservati lvvyj4nr;w 79on 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*z e0mr68d uno

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 oak as7nzy6et+k74 y2gqa w0 0wf 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 unitaci4(wg r fl:1c)6drk r9f v7k of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-t5 r0+ubnyw3 lehird the time. To do so, your power output must have 3+lun rb5y0e wbeen

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 c /8opxip k4r.v vv fyh1):ach5 49scmiar'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. ,vmcto 84mqv z)h. :mqIf the object weighs 90 N, how much work was done inovm)vcz .qh 84t:qmm, 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 a0op:mwvg9 9x +xznj)m 1n6r(hrt y-js constant velocityxn6)prt sv-yx nhor:wj9(+zm1mg0 j9 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 with aue0w:dq2/wqa mc z,b1 constant force of 5500 N for a distance of 50.0 m. What is thz,cdb/q e:1 u0m2wwaqe 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 witkzx+umc e*g,*h a constant force of 5500 N for a distance of 50.0 m. What ise* g+c ,uzm*kx 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 pulled upwar98.t bz2/ ll yz2rajsxd with a constant force of 5500 N for a distance of 50.0ll.xrbjya9zs2 8/t z2 m. What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up alojmvf o-5b;h 3gxb,/p1uuczr ; ng a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m t 6+lhms)dm1bs -ydj8. +4m estw2wnv 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 surface (assume noizr05zk3 p+8h/cqp co frictk zrp /cp5 qoih038z+cion), with a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direc wr)-7 p.-;nzxpbonx5h,qice)fpr n (tion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done whefwp). 5xp,z hrx7pr-)cobn-e n( qin;n 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 graph in Fig. 6-1 rvvmj/ 0 3 (5i ukg2*rmzftf;pix07ozshows the force versus t j5vt0 prix omg3u;f r/ *zf(0z72mkivhe object's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of ther x2xt.ia2,gz force. The graph in Fig. 6-1 shows th xizrx.t2a2, ge 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 in the direction of the force. The graph in Fig rc0,2u4wy nm:1lw eji. 6-1 shows the force versus the object's position. Find the work done when the object 2 yc,u0lj: e1rinwm w4moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at rest,hfkch-;rm5d e hn hj 8f98sl+) across a ef+-jc h5nm;, hhf d89khsrl 810 m level surface. What is the final kinetic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initiall9/;6gp djin) dprl *n,z7cbor y at rest) across a 10 m level surface. What is the final speed of the 7np di b9ldp)cror,j /6*;ngz 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. .f jq*hv9gk i6How much work is required to stop the mass?*fhk6jq 9ivg .

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, whllz36ag+h9mwo6qq m, at distance is required to stop a car moving at 50 m/s under the sz+ qol6waq l9h6gm 3,mame 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/0adxnrhk6gd)2 4ltk c /ek) 5bin(p k 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 thxikp/2c5knrdbgk hlea d 6)k40(t) /ne spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a vertica661dz gol*5obbxz e1kmg8nw s6vaz6 3 l component of 60 N. The force is applied d8oob wa65 6 klm6b3 ge6zvs1g1n xzz*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 /z;s ng*rl(eke2h w4a+ksg e3into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force act* 4e+hksw(l 3eggkn;s e2 zr/aing 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 mo) /ndf ys5sod9ved from a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change iny9dsof 5)ds/n gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 mifcgh udq2 ft4 3:mf:. v57:z hrfzu7j*6gz lu long and rises 2.0 m. If the plane is frictionless, how mufc gz f4ug*: v:m 36j.f u7zdlqrh2f5h:uitz7 ch 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 aalkc0 2pg* us u7xw65spring, causes the spring to stretch 2.0 cm. What is the spring uawkxlu5s0 7p 2acg6* 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 xfm;+ logg3(fpvf m05 60 N/m. How much potential energy does it store, when s5(f+fp 3lmgo g;mfv x0tretched 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 initially uncomp:gf;a,y 0cs aw,kssw ,ph,/flressed spring with a spria; wsk,s 0,yf,cl,hpf/s:wg ang constant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spridl3rqkgb.an b d8*o +ed9(ef /ng constant 40 N/m from x = 0.20 m to 0.25 m? (8 eb 3n(gd*e.kf9dd+ qbra/olAssume the unstretched 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 co coybg,.v;3py3iz9qos qt8 y*nstant of 15 N/m is initially compressed by 3.0 cm. How much work is requiot *b gp.,iq9qcy8z vsoyy3;3red 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 the top of a 50-m high slope:3qw/f3yzzv.,ego rs. What is the speed of the slier on reachif/3s.rv, o zq3:zw geyng 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 tyqoswq.yu.*dtq t.*jit/c 0,op of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast wil,0.tsj*/.i d cuy qqt.ow*qtyl 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 inclin7 d d2c84hl5v;t fl+am1b siweed plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical heighld mc lfaw27iestv 41bh +;5d8t of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m above the floor, its pep9k ukf h;. 7fkgey8;otential energy exactly equals its k; kfegfkp8;e9y7.uk h inetic 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 level2 *1ptofsm( jo with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it ri1(osjf2 mo t*pse?

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 m9fqlfac+ jo 8 m,a6:nv leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, 9a:6v fqom+,fl8ja n crelative 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 p6ln8e 50hvh.je /ry nfj0qr6zj5r p.-c gip3ooint 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what wi gplrji vfr/ hcy3.5p hej0-6rj nqz6neo0.58ll 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 rqy ey3noeu3 m7d/wa/v2e74p 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 3uen 3eqvp/omr27e7 a yd4/ywthe 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 bo,* axkjl8 rw0mttom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which amrlk wx,*8j0 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 spehla m+mcgmt/ go/+u6.ed of the ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and(g 4w4ung:oy2 tf(e lscft0 6r released from rest. What will be its speed at4rgtcu:l6ts (4ffen(wyg20 o 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 hori/zg)q cj41uf kzontal spring with spring consugq /c 1fjzk)4tant 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 mqkt63 3wwdx . ;dk6ead/s, slows down her 2000 kg car to stop for a red light. What work is done by the friction ford66kte3wax.w; 3ddqk ce 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 kxz6r ljk( .gp p:r,-dq lg7g*1t0ccaand a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a 6*1k.p,tlzqp0-cgr: cl7gdgkjar x( stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J of kinetic ener;o7. v4zin /q a4jaazegy. The friction force on ae4n7q. io/4jvza ;za it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a et by;vs3 322whe(wpn level surface. The coefficient of kinetic friction between the mass and th eevww2t3s3h y(n;p2be 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 ousnop ogb2l:*s.i8+j z9jix4 st.(n of a 50-m high slope. If the work done by fricti.p (gsn8l tosiuso4.b x2 zjni:+*j9oon 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. Th ,tykgoh)u hjcxzw(w -e3;e+,e 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 planet ) ux3hww cy;(oh,-jg+ek,ze. 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 f yjjs-+cxeqe- 9*6bo of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass a 9c -*efy+eoqx-bjsj6 nd the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from kt3n fn3,ynq0, 8belz a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on ze ktyqnf0,8,bl 3 3nnit 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 flight of stairs gni/edv6i;0pmk:m +x10.0-m hiiv 0k;ndp :6m+/ixem ggh, 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 velocik/spw(xfz-f+ lg7uwz9-+34qm ni zet ty of 5.0 m/s. What power must be delivered to the object by the fos3+xzi g/p tzl9wf+e-7qfuw ( z4n mk-rce?

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 en,9bn- *u r:- pvjbpc8ftu.wdw ergy are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 7- bp.p9u: *8nr vd,wbcj fwt-u46 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 ridingz)qyjlt8z) 0d. How much force does her foot push with when she is traveling atz08dylj z )q)t 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 p2 l-mgh ; ,g7oprs/va ef(h4nwwzyhz (2)t8mm/s in 7.0 s. What is the average power delivered by the engine? (1 7ephgvhf2 h,-zyp )mmg/;(84( wwo a tlsn2rzhp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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