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

1#

What is the correct unit of worpmndmlck 19eb.fzw0 v1 ;p+,tk 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 g h:+,pbsh 8u.bbzv4oscsk,/ 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 hardv(j0z/o: n wdd against a stationary brick wall, the amount of work you d:(on d0 wd/vzjo

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. How much w hxicwfmw/y( 61o8+ed uu;1efork is being done in holdin(+we /w dic8e1oxyu;ufm6f h1g 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 forwardv 5re t6s8q.j1r6y zg 2jgqqyj ojv-:wckg.9- at a constant velocity carrying a 10-N obq-wz.y6yktj c9g 1gs v8-5o.q:6rejjgj rv 2qject, 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 7/grm+f 4h2 za 4qunhyis lifted vertically 3.0 m then returned to its original position. If the total weight is 3u yh 4gqhzn2mf+r7/a 40 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 object do work on the objeclt;+n4vos, r-c/ ion gt?

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 sig 8c+ mdrw)p 44imyzr7q7nkaf2n of the work done by gravity while the ball mkq ymdfz247rac+r48 7 wi)pn goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) graph, repr l8:ziza p;i3wesents :lapi8z; 3iwz

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 vlj/7;g eade/7kmp )iz s. x), what represents the work done by the forcme/l7)kpidg 7;aez /j e 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 posit+34i 1lpupnvnkky. 1o ive, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is nehwc ccy0/ 62(riqj4:to-tuiigative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the object's kinetic energ)+lq fe v4i)l:/ynpa ly

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 carkh2lj8sv83uic7w op) n q8 tn6, and is moving at twice the speed of the car. Which statement is true about the truck's kin 28iql7sc63 pvj8nonhwkt )u8 etic 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 fast0c7 bxl*zkj 8l as car K, and car J has half the mass of car K. The kinetic energy of car J, compared t*l8z0 xjkb 7lco 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 bouncesgd 4m+q:;wj+ wuodte7,q dq4m back with half of its original speed. What is the ratio of the final kinetic eneqm,;wtmg 4d4 7+ow:qd jde+qurgy 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 pebblk /7ifjvfz4)1 mmxv1fe is moving at a speed of 5 m/s. If both objects have the same kinetic ener/ )m7v4 kfjx1z1fimv fgy, 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 speed 2.0 m/ o *s1j1hsk1pwg1f7+ 7ur ,lyk ca9rfgs. A 1.0-kg mass is moving with speed 4.0 m/s. B1u7 rkj1*,o lyws cg7rs +fg1fp1ak9hoth objects encounter 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 car7s)* f-gp9uflgx l *mrrb(4aa in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, whmasgf xf*7lu-p9(ab)4 lrr g *at distance 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 the Sun in an elliptical orbit. Negle84*q4gh4 thbdb 0-o xwvsxpc*cting any friction effects, what happens to t4dg0 o4w- x4 vq hhpx8bt*s*bche 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 prin2)b qx9akku8 d3co ,-xili d8dciple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential energ2s u +gaa+cb6;f:ttfwy?

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 releasedhznv q:+kwn2+ from rest a height h above the ground. A second object with four times the mass of the firsthnw:+2 +zkv nq if released 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 stretch n3oqg0cw oxaem8) 8 z35.0 cm. If another 0.200-kg mass is added to the swn3cq o)og8m 03x a8zepring, 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 )z:sg2u81p br :bkiyssystem

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 kine 5 lekg,u: c-rspz5/1s,xxnc atic energy K, to its potential ener -5rneas up/zk,5c ,gx1 :lsxcgy 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 dx j:zv8(;a qx9 zmyfog9;vr;priving 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 objecthg8 d 6/me xpj2rpe6nl6+ qxa. and a very heavy object are sliding with equal speeds along a level frictionless surfxagp6 r.xj d2qp8/ e+e6hmln6ace. 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 .q p 3+qo:1hjvtkk1en $m_{1}$ 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 mechanicaj f.v e-iy20hcl energy for conservative forces02i-f .cjv hye.

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 frictd 9b *(tdgm)y,:svh7ve r;cdeion is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top otsc9m ved y:g e,(d hv7)*r;dbf 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 iqlrhj.p9z , ,b0kukf9xxlm53ls t:8gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the ball ji 9.xt5l hm3xb,u0pks89fk :,rzllq 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 4iz9 nes9s6::d t +zwqwuz o*i xeb/b6of gravitational potential energy. Do not ignore air resistance. How much kinetic energy dizos9tqse 66/: niw ew4u:bi + z9bzdx*d 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 7lw0 h6gkr+vion 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 istv)ehy ca-2a3

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 unn ogq9/ 9kpr*uit 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;8m vgwmug/(nyi q 3q+ not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third t 7tn0p vk(78a5cygqvphe time. To do so, your power output must have bvpqy a705(ck7g8vpnteen

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 constan-( )ns,p /mdnttwz g 6ydq*2oct 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 vertically 2.0 m and held there. If the object weighs 90 ig7;7 3j5l yfa2xhm azN, how much work was done in lifting 5hg; z fx37 iljm2yaa7it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at a constaqeaj 0iwj 84v3lzt-l5nt velocity of 0.50 m/s. Whje48 q j 3za-ll0tiwv5at is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N a deja pjs7k3y 61 e+odu.i,4ifor a distance of 50.0 m. d6s.,yk+ejeid34p iaa1jo 7u What is the 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 u;nq2p 82f 19frg nedml99fxpl,l rzq2pward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by th,ndrpr1qx2;9l epf2f9lmg8l z9f nq 2e 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 N4erq4k: ,1udjwo h,oc for a distance of 50.0 m. What is the net w4ouhjor,:e kc d1w4 ,qork 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 along a*/iij )a kvwi- $37^{\circ}$ 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 atb z 9k)rcc8 elnggf avu4kg*x1*c )9w2 $30^{\circ}$ 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 sisy71 jr6(si;.klzh,(f /fiw0l:a-uq ajt pamv ter Sarah in a sled on an icy surface (assume no friction), wit,payj.k(ifuw -ra60vzqs j/al t1l(h:7mfi;h 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 direction of the force. The graph in Fig. 67aglno+1aq m) ujq;/ ap* t5hd-1 shows the force versus the object's position. Find the work done when then7q*pqtu+ ladajm)h ;a1o g /5 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 Figs+5k fgs(4m oi. qk2jt. 6-1 shows the force versus the object's position. Find k45j.gs2m tf(so+kiq the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph intz ce6exgx xe/.-,m9p91n yplm:nt9v7ng n x; Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves fe cgv6l-ztmxnx:x1n9; 7xmp.9 n egyenpt9/ ,rom 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 direcn tx25x.y0toyiw ak;.tion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done whet xtx2nwok ;.yay 5.0in 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 mfv3(6cy,-xvefk acv) k ,an1zove a 55-kg cart (initially at rest) across a 10 m level surfaka ck1ez6,xfc)a 3vyv, f-(nvce. 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 (initiallwh/ )he cxuy9z c,.h*jy at rest) across a 10 m level surface. What is the final spe/9h*,h) xhu.yccwze j ed 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 muchpc 07ktrk+ u78 +ssnot2;lvs h work is required to stop the mtrkcs;8772pkls++ s uht no0 vass?

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 irhllrh x76yc-d i4;dc/a ,hc ,s required to stop 6l rrhdccl/,x4-h7 ,cahi ;dya 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 10yx-b;t:e)( t59mm hhhow/ v+t* ttxl v-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart ley h;vxt t: ow /vtel(*h)5mm-bxt9t+have 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 hori2)wnt -hgqs m)zontal component of 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along th2q t)h-)m ngswe 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 h1+e .bbeh- 3tyw0u etinto a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a .1e-+utyb ehbwth3 0edepth 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 movp eu;ex7qcv.fq)fzg; zo +- k9ed from a height of 7.00 m above a floor to a height of 13.0 m abovep;f+xekog-c 7z ;.eqquf)9z v the floor. 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 inclined plane. The plane is 4.0 m long and risxpk 2i*sn65 pfes 2.0 m. If the plane is frictionless, howfpip 2 s5xn*k6 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 the spring to stretch 44cxhv: wd* th2.0 cm. What is the spring conv:x4ctw d4h*h stant?

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.p5/4cvjz;cd z c3 6fyg How much potential energy does it store, whenvcfz;j3c z /y54dgcp6 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 comp(srrk3g f20zse k)a 61b gmf(lress an initially uncompressed spring with a splabrf)6(1kfg32s0ekm s zg( rring 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 w p*kelevi l2.cfz7cs y28).uspring constant 40 N/m from x = 0.2087esekw.c)lcvyp l i*2fuz 2. m to 0.25 m? (Assume 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 constant of 15 N/m is initially comx0xz a0:4 ixz. 0 hqeu,x/riiopressed by 3.0 cm. How much work is required to00hx .xz/0xr4 ozuiiei:aq ,x 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 re60*9fag fwzi3n5zd ywst from the top of a 50-m high slope. What is the speed of the slier on reaching the af zz9 5dfwywn i0g*63bottom 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 speegwwyyx.8 p 2k1d of 4.0 m/s. Neglecting friction, how fast will she be movinyyk.2wgp 1x8wg 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 hasa8-oghb(gh7s v.l 7w v a speed of 9.80 m/s. What is the vertical height of the plaslvg - bh7 hgwa8(7v.one?

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 0.7ongl11vg* h n9itgg.xbb3nf,t0- 0q r0 m above the floor, its potential energy exactly equals its kinetic energy. How fast ihg1gn f900nttb1v3* l-qx.gi rnbog ,s 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 l eczpz 8vt gg7qnb.pab.+:(f-rkew ,2evel 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 risez-vfb: bpt . ,g7rc(zn2e+8ewpa.k gq?

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 up.h)4z gv.ge of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launcp gz)uhveg4 ..h 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 c9 qi*k(w4dd am y9 ea/;e-b 0ruv(dmym above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roly mddd*avwc(m e9 ;/9u4ryeba(qi0 k- ler 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 if o)kt5i,ua:v r6w2 lof 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 t ,kf25o u6wtav)r:iilhe 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 xrfzf-hs-v 6nr kjc3rb9 0*x)1s8jc t a point 30 m above the bottom of a dip with a speed of 25 m/s (See Fig6cjr skc)h-xf8rs0t b93xnfjzr- v1 *. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottom of its sw -u2x ;uu1 +mz th*p1)uaancmuing (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 cmx+wu 7dkj : pzk 6dsox)5v21wg away from the vertical axis and released from rest. What will be its speed at the bottom of its swinup g26wvd5sk k7j1+x :xo)zwdg?

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 horizontalfva5(v2tx* v4fnt .rv spring with spring consvnr*a4v fv x.vtf t(52tant 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,*(n(k4k wyjta slows down her 2000 kg car to stop for a red light. What work is done by the friction force against t( *jnkta( yk4whe 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 k db,ov (9agz0yl5 w9whorizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide befbdz(0w95k9lwyg ,a ovore 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.4zdk30 . 4fccdtmb9 x/ky/zen It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far kb9xecn4dykc3z//d4 m0 fz.t 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 horizc fakxqpo *6,4ontally to 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 dist*6 ,4kqc faxopance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. If the work .y8 d en q ad 4+s/n(6wkj3zvqtzs9s4rdone by friction is+3(qs sznnkat4 e6s.yqjvwr 4d9/d 8z $-6.0 \times 10^{3} \; J$, 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 risemtv9f.i2j o-ty v2v0e s 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the yevm-v 2vf.2oi 9tt0j 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 relevglmdn+8wf3( ased from rest at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along twm8gv 3+(dnlf he plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikesy0r9;r ql b;bv the ground with a velocity of 7.00 m/s. What average force of air friction acts on i ;;vybql9rb r0t 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 enausr,3c( uv5vgp*h s/ergy when he runs up a flight of stairs 10.0-svhu(5r*u3a, sv/g c pm 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 of 5.0 m/z*9wwg vdn+d -s. What power must bewvn+ d9*z-g wd delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs forbjwi6ey3m 2ns 6m05u 5jty5xd 1.0 hr? (1 hpt0wbm5m5j2yx65 ensjd6 i 3yu = 746 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 r2xohzvlu+i 1.c -2thl ate of 500 W while riding. How much force does her footol 1 luzvhx.ic2+h-2t push with when she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s iw)jptprba)*12hf x6 in 7.0 s. What is the average power delivered by thebfj a)hr tpxw2i6 1p)* engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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