Physics Unit6: Work and Energy - 无忧得胜-网上国际课程 (5edu.win)

1#

What is the correct unit of wor0utvlm ))ei-gj ; jn5lk 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 syste6ehla-9ljjgdyy0 q:: wt44j cm 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 a stationary brick wa1ob;77mnopt rcs3/u ell, the amount of work you us rb7o1;oc73p n/temdo

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 wok (okn nzf5z:1rk is being done in holding the box in this positionkf5n:1noz ( kz?

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 pk7m 13b;-4 phq1ze rphls0bmvelocity carrying a 10-N object, tb;-zr pkl40p13e mbhhqms p17he amount of work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned to its original posc -hhd:n0*t 77lo7 hnipcb:+vfh9a *trl rb,sit:archchv d:*t l ns07nb hbhi9rf-*7, l7t+opion. If 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+gd3q(irnhlib 0 0d+w 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. gfg(307xu lwe Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gruegl(3fg 0w7xavity 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 chta/khdhou,6 y4 )hc:urve, on a Force versus position (F vs. x) graph, representso/dyhth, h)4 uahc:k6

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. xx.edh6 x,4qxz ), what represents the work done by the fodx ,exz.xh64 qrce 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 obui n 2lxwh/b75ject is positive, 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 negative, then the on*: f9z mjcp+ybject'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 tqqzj58ly03yui3 dy+p yzhs1y 15 k /f.utjdi7he 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 twice the spee ewv:it-rw 7.bkdp)*d8d hk5ze9jr e4 d of the car. Which statement is true about the trucketvk4 .jr9 wdb idw d hzk:pe-)8*7re5'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 e5roij -l: 7/pkk4geym74kwohalf the mass of car K. The kinetic lo m4kjk-:y7k/r7 4pi5w oegeenergy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces bpu, 4siug, g)fack with half of its original speed. What is the ratio of the final kinetgsu, gfu 4)pi,ic 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 apf g3)-cl8i cg speed 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 ratio of the bri8plc) 3fgi- gcck'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. A8nsx3 tp-gda : 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rxa:gtn -s 3dp8est. 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 distankk2 /b0zy vy5vce on a strakky2 /v0yv zb5ight, level road. If you had been traveling twice as fast, what 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 a+s5e mknm6nw;gby :v3e, rt agv1/ 0utn elliptical orbit. Neglecting any friction effects, what happenbtg /sm,v6ae1nutv 5r0;:+e gyw3nkm s to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy )p1 +zpirz11xoqan5ph, 1-9cjuo5 z tizoim: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 potential enp9x k.j4; dlaxvn+ *doergy?

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 7p2cmemfve90xv0;7rzy) )vit+5p w f xpb ck0 h above the ground. A second object with four times the mass of the first )mpcpk f7 00me rvwbfxt7zcy pv0;+5)9v2ix eif 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 0keym05peh)lg iu2 o*to the end of a spring causes it to stretch 5.0 cm. If anotheregk*oe2lu0m)i p5hy 0 0.200-kg mass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a sbh:u;a uafs:kz n gku:7 s(m +h-4l;spystem

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 ihlyssq pz0nbgi (y/x1vlo e9-7;e 5t/ts potential ener 5/h 1xllvsb eti;7e-9zqno0y p s(/yggy 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 ;y5 ),rvku*1f 5inpy cl-ozgycar 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 heavy object are sliding with equz7*ugz r5l r 0lxit mm.i9w.cx efo:56al speeds along a level frictionless surface. They both slide up the same fric*ogu05m:t e.lx5miw r 76zcr li.f9zx tionless 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 mzul2v e32g-m$m_{1}$ 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 cw.hn zs(;2-qe st/1 kuq h+imof conservation of mechanical energy for conservative forceshse/.zqkt-+i2w ;1nhs (cmqu.

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 t.4k7gohyk)ut g+ br i8op of a building, through the air (air friction is present), to the ground below. How does theo t7h4.uk)b+8ykg rg i kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distan )jbapyr-p, g,ol f)2dce and gains 30 J of kinetic energy. Do not ignore air resistadjl) ba ,po)p-2, grfynce. How much gravitational 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 potential enerwi6wz1g tss(* gy. Do not ignore air resistance. How much kinet wts* (1s6gzwiic 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 of pdf060+d6b.akacluor i v5a3energy.

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 is0 i-t6gpg*i *9yiheb*c u5n obq w1s7u

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power expressed in SI unitsh-k1 uda/ a:rh?

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 un2me/) :pdi lfg*f(q0fv x7vzcit 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 the timow jb rro4 pebd95+(sa)vw) gq3.yu.fe. To do so, your power output must ha4vyw gbj(ra.d.fq3o w9r)+s 5beo up)ve been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, thej:4m/dw)):jw wp,qganvry ,s 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 +9k4ji 40ga7 fb:s+l rmwr5qu nj1tmrthere. If the object weighs 90 N, how much work7ukq a 1 49n4rgm r:tmijbr05sw ljf++ was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at a constanf.nbmr.4 v-5uge2 ohf t velocity of 0.50 m/s. What is the work donorum ..4n-f2 vef 5ghbe 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 conk ;ttijr 3i 1c:0fz +mxsnq2g9stant force of 5500 N for a distance of 50.0 m. Wstnq3i1mg2+f0k :9r tc; zijx hat 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 upward with a constant force of 5500 xhtd 2v+yl*kxm 6c.vmd:- +laN for a distance of 50.0 m. What is the work done by the dvyk- tc.:la+dmh 6mx *x l+2vweight 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 forc qdj w)cpbs76j q54h+qe of 5500 N for a distance of 50.0 m. hjp 7dq)+45jc6sbqw qWhat 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 along a/a7xil. t8sgx $37^{\circ}$ 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 e4 rd4agic,k7bm0 gn *r2np2e 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 sizyil1o 8pt / +shp6,a8 wryrhqkf*q*/ster Sarah in a sled on an icy surface (assume no friction)p/y*6,i oslr wkh 1qr8y/at z*fh8q+p, 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 direction of the force. The graph in Fig. 6-18ae76chyu nd 8 shows the force versdhna8e y 67uc8us the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object ms.s 06i-3 ylbqgcjr.in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when y.rlbcs - 6jgs3mq0i.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 directpb ivtdsbzq1) lp3 y.w(mjtu;3w -2m8ion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 4.0 to 6.08 pb-ptw;d.32ib)1(3lts vwquzjmmy 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 objecwh5+ 21h wdrb ru6w 81wk5xttat in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves fro h51b dt htr8 r2+6wxwa15ukwwm 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 cartk(:ywtk+ 7aq yyups,7 (initially at rest) across a 10 m l 7wuyyas:pk k,7tqy( +evel 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 cvo,qgj.;3( expfdd0 iart (initially at rest) across a 10 m level surface. What is the final spe(3 egj;f vd,q.dx0ipoed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much wor*d+ 6-en2aj bq8gv zykk is required to stop tdz ja*v2ykq 8g-n+be6he mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance zuiqm; 7 y9y9s w1xbz7is required to stop a car my91y7x9q zzu7s;wb mi oving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is 4+v5rseja q9 ucocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible arseq5ujv9+4 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 compoq)4v-gg edyo 8nent of 60 N. The force is applied to a box which rests on a level frictioqy g)d-8og ev4nless 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 pqe ,85v4y,d s otajk 5(lh)jv hfjj0(shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth ojvfqhy 4,pte)80l(( jo,s k h5ja5jvdf 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a flri)x571y9n)qfr: f5xn* /n gwztz jqfoor to a height of 13.0 m above the floor. What is the change in gravitational potential energ gfin: 9nxnw7/zf tx*)z5 y5 rqjqr)f1y?

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. dzuy 5a8fj9l hsr65; jx-t dp+ The plane is 4.0 m long and rises 2.0 m. If the plane iar;h5l6s9j 8d5yjf x -tp ud+zs frictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to stretvrnv q7bb-- 4 kvan4g9ug/.ln ch 2.0 cm. What is t-7n 4a l9k4/n.q rgv bu-vnvbghe spring constant?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a sprin6mhhn, * 8ex*v,:in ajt(qmdfg constant of 60 N/m. How much potential energy does it store, when stretche*dq nxietf* ,m,8a 6:j(hmnvh d 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 uncompre.daf+/oyrc 3issed spring with a spring constant of 25 N/m by 10 o/iy .d+a rc3fcm.

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 springh, m7.p4 2t/nq owsmkv constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched positiot/4k2 hs.pwm mn7qo ,vn 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;zzx0ura ;(dkr (v9c ut;f qr0 initially compressed by 3.0 cm. How much work is0 ( vz;(udfx0rauzt9;r ;krq c 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 from the top of a 50-m high slope. Whatrzd car29+ mc8x,s2ua is the s 9ud8rsmz+ c a22ar,cxpeed of the skier on reaching the bottom of the slope? (neglect friction)

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 with an init,vm-oz3 1 xa4lg, feloial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m inv -1o4ox3zfl,g lm, ae 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 frictiodp idnjb(.ksb)o);g/s1ogd a azj3 30 nless inclined plane. At the bottom, it has a speed of 9.80 m/s. What dabg(ds3p s)g;z i/dbj3 1a)nko0 jo. is the vertical height 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, 9jc/ ytx j -m.gx:kf.eh(uh-+s+ nudv its potential energy exaug9hdjjf+k c /.. hxm--s:u+tyn(v xectly equals its kinetic energy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground n/la6z b1nx,jlevel with a kinetic enen6/n1,lxjb a zrgy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy of 220 J. otm5le)61 tsj ;zin)cAt the highest point in its trajectoryjotc 5 tz1e6sni)) m;l, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the botto9 yse*bngdc l-w*z9+vm of a dip (See Fig. 6-2).n -+ wbcsy *lg*vde9z9 Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the 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 f6 1- ac3*:gropznyof(lpk( t 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, (or(k-gycpl*anf o3pf 1z:6 t which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip witrb1 i4*ubohnny ku7 -y 4az*j8h a speed of 25 m/s (See Fig. 6-2). Neglect friction, w hy 7b4a4z8-y*jo 1binu*nrkuhat 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 s/t pc:/co9quopeed 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 2-kg pendulum of length 50 cm is rbzmxqew6 9i2 hzn+95 pulled 0.28 m away from the vertical axis and released from rest. What will bqw 99ei 5n2+zzhxmbr 6e its speed at the bottom of its swing?

A. 0.389 m/s

B. 1.037 m/s

C. 1.556 m/s

D. 1.297 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 horizontal3ct yag-6ubr+ hnd654js0vy z spring with spriny gd yu4zbsn0jr5 +c6v3-h 6tag constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down h*xph l ze6h r8/8:tjurer 2000 kg car to stop for a red light. What work is done by the friction force against uxp*z jr t: lre/88h6hthe 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-kgr62 ,l kej;ds vfw sx8ueazauyb5*5/ 3 object and 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 *; x5w2fd3eaky8ubj val,/u 6s sre5z 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 zwu+-q)4d 5q2 2r6bekcu zdf wJ of kinetic energy. The friction force on it is a constant 0.50)cruk5q -zb+ d46f2 wz2w uedq 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 apc0yuth- e8 9bjkd4o +uplied horizontally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass e4cu0 bjotyh- 8kd9+uand the 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 of a 50-mdcagyh-6aye5e5 2v yicz t0 ;9 high slope. If the work done by frictio26gih-5 0t;cy eadzec y9av5yn 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 pushedjfxj 1*a:k 7qwl ei8l6 up an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requil k7wj 1ja68*xlq: feires 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 zc1bqel. 46n/+ giyicabove 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+yzc 4e1l/ig. bqn6c i 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,) igo/. j+ 4acpvdl.,f9v3lkbdoxk/v and strikes the ground with a velocity of 7.00 m/s. What average for9podck jd34b+.i.v/lk ov,/ fvlxg)ace 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 : xvyy t4iyrzrs(u(-p *40kxxn25 lm nenergy when he runs up a flight of stairs 10.0-mm2(zpl0yx n*4 -xs urtyxik v yn(:r45 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 of8wpxuq rt: c79 5.0 m/s. What power must be delivered to the object by the for:q9rxcpt w7u8 ce?

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 runsp5af:j; v ou xo-4+toy for 1.0 hr? (1 hp = 746 a ouv4;o5j +t-xpy:o fW)

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. sotd-h66n6 5rd +siklHow much force does her foot push with when she is traveli 665nsts lkorh6i+-ddng 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 accele5s6v5te(c sx trates from 0 to 25 m/s in 7.0 s. What is the average power delivered by the engine? (v5s(cs5tx 6te 1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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