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

1#

What is the correct unit of work expressed inq 8fbgspx3l-0 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 9cbq+6o(f,b d 8xdxcfbn m0,gif 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 ha 2mre2n ljxaub-3+3bp rd against a stationary brick wall, the amount of work yo32mbpal e +x2 bju3-nru 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 tm 0 (zsyyzeib)- k,c)nhere. How much work is being done in),sz yk (cbmy-z ine0) 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 forward at a constant velocity carryi ; 3)mxc*spckmy+qqj :j m/kn7ng a 10-N object, the amount of j p7cm)mj ;:q+m*s/c kxn 3kqywork you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned to its.ja(s yd) zsl; original position. If the total weight is 30 N, how much work was done?(yls)jd z s;a.

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 fnfb-;a c t,dqppau1sfvc :84, orce acting on an object do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up.;+ex ozt cfh qrj*)m/0 Compare the sign of the work done by gravity while the ball /zfjt+h)roec*0mq x; 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 (Fwoqr)g*. .n,vv8 fytp vs. x) graph, representstfv.qy)*n g.po,8 rw v

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the work done b8deatb(wp (4ka-ln6y y the force (dbaa4t6lw(ypkne-8 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 kik9g x tca;rt0; ga6md+netic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then the object's kinetic eneckb)ou e7av5 igj04 /w sfbf(,rgy

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)oqbykikgcws+xhi+l a m448 k tb;. 42 is zero, 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 u96g4(oek+ tpdrnu r )as much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinp 69)+ gou(ketd4 urrnetic 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 a5yp /g63yl cnfast as car K, and car J has half the mass of car K. The kinetic energy of car J, compared tgnp53cl a/6yy o 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 botl4 tr)jbnw4 u ln7p/-unces back with half of its original speed. What is the ratio of ther4w-4blp nuln)tj/ t7 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 sslx,:n ;e 3j utzc1cr9peed of 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 rati 1,jt s:unel xc9;czr3o of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is movingb 6 pvt0mhgr6* with speed 4.0 m/s. Bo hgrb6*0pt 6vmth 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 car in a panic, a7k .hy cu1t.xyn5emy 2c:ll o9(xu v)hnd skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under t: .m (7c9h1xl2htyko5u nly)ce xv.u yhe 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. Neglectingdvyp22xge 28 i mp6zdwfy95m( any friction effects, what happens to the planet'ppiy6zdyw (5f2m8mgxe 9d22 v 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 pr0yfqkc 3zw +:f11omq iinciple.

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 potenlq3 i/ x3luch,qu 74kxtial 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.(agb tu(x wdqcj :h4; above the ground. A second object with four times the mass of the first if released from the same height. Thega.wx;c u:t4qd h (bj( 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 sptdui)at b,tip0j+s iu82q +:qring causes it to stretch 5.0 cm. If another 0.u a2):s+ +tu,i0jitb dtqi 8pq200-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 energry;(5tx nl ydm887cnoy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to gs*t-cy 5nx k2its potential ener -2c n*kyxsg5tgy 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 c :fbp4mu.a ; bbrq1nzn, 1aik1ar 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 very yre yls.9g 6,p*c -bffho:m; gheavy object are sliding with equal speeds along a level frictionless surface. Theyc9fyhgbp; *r: ,6m y.-feolgs 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 l;ic; vh0gikft030 bu$m_{1}$ 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 conservx r sna*jeenxq:2f :f7-)z/ gzation of mechanical energy for conservative forces*q nxe-jef:xz g2azf7sr n):/ .

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.hqc j9spirw ppq8 * rzy/2g35 friction 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 of w5r9 p sq i8/yr qz3p.2pgch*jthe 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 3z l o/vkf,b98 r/knjcbs.m28h0 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy di os r8b , 2jhczn/fk.k9bm/8lvd 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 potential energy. 3iinphs ;57zm Do not igmz3 hni7p 5;sinore air resistance. 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 conservation o0j tw*c9an (opf 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 ul 7pfmx9;+lw

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 unitz 6 c/enh 9kh1 0j-*ajdiktvn9 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 ny-.prz;:jth3) q: k +vm f:ilbbfhj* b :d5izkot 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 ,eaxaq,ge to,y./t2w he time. To do so, your powertw,o a/ayx,,e2 t egq. output must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleropf7b.q ic:7 iation, 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 v;6q.nod, pfjyr n9- 5q7njhc.dcocqk 8;wj;oertically 2.0 m and held there. If the object weighs 90 N, how much work was done in lif89kn5rh. jo pn7;cn,ocd. qy-dj;6qcfq o;jwting 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*sp ) +m(:kpgjn9egbg distance of 1.0 m, at a constant velocity of 0.nb k +j)gpm:s(9gpg e*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 j/h 48ujrhov5 ( qvs.cbw-k.ojvy7 y3a constant force of 5500 N for a distance of 50.0 m. What is the 3jhv8ubq(svr.koj/4.7v5y jh o- ywcwork 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 with a constant force of 5sty 1ry4r6bn7hnm -.m500 N for a distance of 50.0 m. What is the work do bm-ty yr1 7nnrs64.mhne 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 upward with a constant force of 5500 N c+; d9gjg7l1mn-rqmffor a distance of 50r g flm-79dnq1;gm+c j.0 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:qv 2bhys)gnzoh g 6)0.0 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 dow mj;rhs ft rt+3ub1y3vfy: *u,n 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 sledt61h- pewqevyw5l q0/ on an icy surface (assume no friction), with a forcywt/ l ve e60hp5-q1qwe 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. The7hppt 83sy, ,gh yuyu, graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 2.0shy ,,t8ypg73yuh,up m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direct:hn(pl6,s 2ippsuamz ) vopf:n0: wf 6ion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object mo h )auf:pf nm 2pws:szpn,p6 :(ilov60ves 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 ofu 73ivuh)a/gw the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 4.0 t3a v)wu7/ug iho 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 direcbz(en.v q: 6elmsn s36tion of the force. The graph in Fig. 6-1 shows the force versus the obje36e(mzen s6lq .vns:b ct'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 to move a 55-khw2c or:r vxo: c-5nqweb9j/1 g cart (initially at rest) across a 10 m level surface. What is the final kinetic e -n1b9w:qc2wvroxr cj5/eh: o nergy 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 200g+ di:g4mz (tp N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface.gzmdit4 :g(+p What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving witlo.psch +nde5.v8+lbdcu4 :s h a speed of 5.0 m/s. How much work is required to stop the mass?c8ns ep.cu.vls:+l hd 5bd o+4

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 infd:cd*m-bh b+zxf tmfi: ; 0e-itially moving at 25 m/s, what distance is required to stop a car moving zmfc- mfh:*+: -b;i dfed0bxtat 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.af 9 h6 d;.advkzk.qtkcl *3x is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the darta* zc dk.3ldt6 ;xkq.kf v9.ha 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 and a vertical comp4gru3,tt(te wx5wa qwuz gt* ,7q-kw(onent of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart st,xw u,aewt4r-tqt(k qtzg3w7guw 5(* arts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a ba e855a;.kvcuncebm(y70 jm7x shf .msle of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. fkuy7mms(7j;558c ae shv .0c. m xnebWhat 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 heightz:b hp.oe,nmwayeq28z7 +o) n of 13.0 m above tn),oa oh8.ey:zp27+zmw qeb nhe 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. Theg1pk75y4x( l m w0cltz:7 guia plane is 4.0 m long and rises 2.0 m. If the plane is frictioc 0mp l(7l: g7giaz wk4x15yutnless, 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 onyv ks..p q3g8eto a spring, causes the spring to stretch 2.0 cm. What is the spring constantv3.ep8q kg y.s?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much poten.3m5 q x.k ,kijl.ceortial energy does it store, whenoklr.c.eq3. k5 i xjm, 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 initially uncompressed spriyx 7jer(v aik 8rf/n+,ng with a spring constant of rv+nfay, jx(ri e87/k 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 stretcae :1k/ fm3 ld 6qfjipx)cy6ab1rcp5( h a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m?a d/ p1y6j)fxi cp5mlr:3q k(e b1fac6 (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 compressed by 3.0 cm. H 6/j) l3eb dbvha80-;bmuc oirow much worku)blhciv/6m8r bdje03b o ; -a is required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest jcn3s.dq ymxd6atc9q+ ees2x-0)v9 ifrom the top of a 50-m high slope. What is the speed of the skier on reaching the bottom of the slope? (neglect fri-a 9 mixcqxj ce2dqs3+ d0.ns)ev yt69ction)

A. 22 m/s

B. 31 m/s

C. 38 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 wit(+ 3x+u- rvclxp8c ctuh an initial speed of 4.0 m/s. Neglecting friction, how fast will she be m3uplvr c++-u x8 (txccoving 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 tht3x5utai x g-,e bottom, it has a speed of 9.80 m/s. What is the vertical height53g xaxu-itt, 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 the34yf jyhspz(u+( hf- g floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is fug3sfj(4z(-yp +hyhit 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 0g hhzyft41l rx1,v*o7; kjdzN, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanica 1y,z 4t kxh*z17rd hf0jlvo;gl 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 x *xs ;x:z2 tmp/7yunxwith a kinetic energy of 220 J. At the highest pointmyp t/x2z n*xxu7x; :s in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from r xwwni,,/ecy,pv,u /h est at a point 45 m above the bottom of a dip (See Fig. 6-2). Negx h/e ,n,vypc/w,,ui wlect 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 starts with a speed of 5.0 m/s at a point 45 m above thew+ avl;axrq/ + dan18o 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 avxa/r+qn ;al+d8w 1o is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a pw qcei. 5zgo-+oint 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 roller coaster at the top of the nc-oz5. qe+giwext 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 bar ;9hkinpdbn lvl/f2lio8f3 h52x06 mll 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 2-kg pendulum of lengti9:l.i 1v 0e1gd( :v6wbbkza a3fzdr kh 50 cm is pulled 0.19 m away from the vertical axis and 1zkd0w:fbv3 6. zdi1ra iek:gal( b9vreleased from rest. What will be its speed at the bottom of its swing?

A. 0.257 m/s

B. 0.686 m/s

C. 1.03 m/s

D. 0.857 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 initia)3le6bt :z g.r3c rz,k mf-yzclly uncompressed horizontal spring with spring constant of kzc f6zye3.)3,cgzrtr ml :b- $2.0 \times 10^6 \; N/m$. 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, sloj,e+f xxc c9c8muk: ahd-l/4zws down her 2000 kg car to stop for a red light. What work is d/-c8hc+j:9xxfl4ac dzm ,uk e one by the friction force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a+q ; shq(j;jbk horizontal surface is 50.0 N. If the initial spee( h;s kq;+jqjbd 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. It has 24 Jel5e 4sd3 oby 2dzs(p: of kinetic energy. The frict yseb5 dz 23eol4dsp(:ion force on it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level surface. vk ja5((mha k: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 kineticmakv( :k5a (hj 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 tpsrv5 amwv)l49o +4 6j,m nly: 6vulvhop of a 50-m high slope. If the work dov+:h94rv)mp ynvljlv u wos6m, 56a4 lne by friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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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 yp.rge5 l* q;kv*q-dd4.0 m long and rises 2.0 m. ; kv *r-*lp5dd .gqyeq It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined at 20e l gfp8e:0gf:+ vpbcy7above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. +lf:c gbev :8p0gyp7f What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikesxnr* 2w4,t x/+jgvf-ca tnax8 the ground with a velocity of 7.00 n4xc,axg *-n v +af/txtjwr82m/s. What average force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a flight of stairs 107j7huxof 86qkg-(ict) unu j0 .0-m high, ciu7uhqtoj(6x8nk u0jg7 -)f 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 anp97 rem ob .:kmj33flq:m q uf4qa7zb3 object with a constant velocity of 5.0 m/s. What power must be deliverjqlm3f 39a73e :oz: pq4f.m7urkq mbbed 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 ;ibpg19e s ve8motor that runs for 1.0 hr? (1 hp = 7461p beg8s 9;ive W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. How vm5a8qn, 8vbj3p l+-uqhedw *much force does her foot p5unj,pwv8b 3aqm+l q-h*v8e dush 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 ok ;2ss 7re)i/v9xqwqm/s in 7.0 s. What is the average power delivered by the engin xr/;es7v)qik9 w2sqo e? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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