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

1#

What is the correct unit of work expresse. zp(r* lpb.zmd 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 i(ify3 xnw16vv.n) fqgf 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 wall, the amoun2s j2o8zs/er7yrhp oy;x*u v4oj:bs 5t of work you do2: ;sr/eo x5 o7rjb2 y4phzou8 jsys*v

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 2.0eun/ymqjd+ *6kgdz 5; m vertically and is being held there. How much work is being done in holding the box inq5dm*d;6ez kn yju/g + 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 carryin x 5 -2+3d/twj ze+vewcxz4fprg a 10-N object, the amo+pzevtjx/4rf53e2+ww xzcd- unt 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 toc20hpdo q3.zzaoa+ 2*gwpx8 k its original position. If the total weiz*3ckpa28ph o .a wg20qozxd +ght is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an objy0rrw b slit9/a/ 8ff4ki:;sk ect do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare t ),; u)0kf9yobz quapfhe sign of the work done by gravity while the ball goes up with the sign of the work done;a 0p))bfzuq f 9y,oku 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 vsjv) s7c c4*)w jppk6)sbew+ll. x) graph, representslp kspw lc )e+7vsj4 6j)wb*c)

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 ( 7a).xe6vfo9s wj0uq 1*x eincF vs. x), what represents the work done by the force jac7e.9uf) q esnoi6v 0x*xw1F?

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 /neaq2hqp ;6zb0vfjg,)5sj5t jhho 3 an object 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 object's kinetic ener em46 fu//m ni8g)qwubgy

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 kineti -3jcvmwuz6a1 1.n qat (9zoho xgt25 cmh8tb+c 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 asc*zrgy gb4qur97 /bn . much as a car, and is moving at twice the speed of the car. Which/ u4g7 rngrcb.y b9*zq statement is true about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass olo bfbf604be)uf/:gr- y( dc s5r7yhvf car K. The kinetic energy of car J, compared to cav7)- u s(drgecb:byb4hrlff0foy6/5 r 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 walkt:fgs-yjhn 727ojg6c)c 4 a tl and bounces back with half of its original speed. What is the ratio of the final kinet j)jc 74ak-sfcgt27gn t :oh6yic energy to the initial kinetic energy?

A. \frac{1}{2} \;

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of y1rw d7*cw.al xx n5x-j+wk*g 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mlxwdxa*+kx-r. w gj n 1y*7wc5ass?

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 3,qaxo ydi( lgs9:zd8yz ld-7 speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater 7:,l8 9oqil 3dxzdd(gay-zysdistance 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 distance on8 z4bqqp0le k5 a;ngx7 a straight, level road. If you had been traveling twice as fast, what distancen0x5 l ea;q8pqgk bz47 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 eesz zy36n.e :xvfbv0yda /0+in an elliptical orbit. Neglecting any frict0y nyz/d6.x+:vveszbefae 03 ion effects, what happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

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

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy princw. rtf m91 q7uxxf+6lkiple.

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 energy?,ssqo 6(v fxnr :24zpc

A. Yes, as long as the total energy is positive.

B. Yes, since the choice of the zero of potential energy is arbitrary.

C. No, because the kinetic energy of a system must equal its potential energy.

D. No, because this would have no physical meaning.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the groundz8mqr2fz x/kzzh8f9xr- r*- f. A second object with four times the mass of the first if released from the same r2 k xzm8f-zrqf-fz z*8/rh9x 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 5.0 cm. If6+vv0- u,ypic+ pvgy c another 0.200-kg mass is added to the spring, the pop i60 u gcypyvv+,vc-+tential 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 mechanicalfwp *cux92s: v energy 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 kinetic8 hzaxx7c8p lpxn:t6 0(e4 aqe energy K, to its potential energy U:a neqp0xpe86tzxchx7al8 4(.

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 driv9d xhw*, 11knoj4uga ving 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 any xsmstpq4k1;ies7*, g5fve2d a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill.24;m* vtk15ipess xefygs7, q 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 w wx-bh9s lz;7yw*d2f f1yymg7*-ab k$m_{1}$ 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 mechanical e*5zvp * nad+h2lxq cr l5dk9l*i :gs1unergy for conservative forces.5lv*dl +gcz2a *nlqxk ri:h p195dus*

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 friction is prv agja8 2ue2ayvl,/ u+esent), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the po yg+l2/v2auj8 v au,aetential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Do not ignore aiu hjr8ze * qh:t:p94:.wextezr r z*:tz9rwtuh:p:jeqxe 4he8.esistance. 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 poteqw 1sp w2.lhw 2 r35jm/smsls-ntial energy. Do not igno5wqjw2 1rp /s. 2mls-m sh3wlsre 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 gzb7 s-zq(gl;of energy.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is*uw :kq/uzm(wg.o j )v .lrv.x

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 units? .*e( (vcggknkyhq ifsj35-,z

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 unit of powerbmezy21m: 5ro a1l 73auso rq+?

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 ao y/x7-ay (b2xv;mkcdid 3 times the work in one-third the time. To do so, your power outp o-b(/aa72yv;myk c xxut 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 acceleration, thx:n/h.zt8 b* gd c*ud a0gcke1e 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;g.9c et 0p ss/qmrv+w 2.0 m and held there. If the object weighs 90 N, how much work ;tm+/ q c9rpg0s evw.swas 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 f 90 z3owr5slphg(ic+the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work doneh+ sgi c5l(ow90r3pf z 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 forgbjal m)a163z a distance of 50.0 m.) 1ab3z ljmga6 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 upward with a constant force of 5500 N for a dis*rf;k;5h +9egwci uzstance of 50.0 m. What is the wo;+; rchzwu g9*skeif5 rk done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward w:t r oc6c xk3edc1u-6jith a constant force of 5500 N for a distance of 50.0 m.6t6ced3o 1cr-:xcujk What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up along a kwgwzjdl:xb;7(x33j $37^{\circ}$ 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-y9p tq,few idx+sxxs* ;;s u. slides 8.0 m down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little siz,+ k wopt 1s znlt5l:4/0cptrster Sarah in a sled on an icy surface (assume no friction), with a force of 60.0c lp4 /k5tw :ttz0+znlr1o,ps 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. n cqputg4a 2 i,q7i;nvp0yb)(The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 v)ubqg, c; y(q iintp4a07 n2pto 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 grapn0vdtx4c uc sdp01h96 n78 tqph in Fig. 6-1 shows the force versus the object's position. Find the work done when the objnc4 nupt6ph7d d010stv 8c9qxect 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 t f2r-, 68xfuqfbgq6c9nurlk7 )pl-64b c ca jbhe direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when thfjfxp -c) 7bru ,g62 6bqf -kbqn cr8ca49l6ule object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in vaib2*7kp3o. 4rx 0wl4fnnbw; zceb ukp( 2w0Fig. 6-1 shows the force versusp7rwz2b 4 ;ic23b4k(nwo uvfxka00* benw.p l the object's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applcry tquoo*oo2 33zpl:z*e 23gied to move a 55-kg cart (initially at rest) across a 10 m level surface. Whatrygl** cu: q2o3pzzt3oeoo2 3 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 5d kdt6fbbut l5a7*,tle)9u 2w s mi/2brz,6ht5-kg cart (initially at rest) across a 10b)2bd/ztwttbs, 97*6 r mk f de6ali5ul h,t2u m level surface. 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 with a speed of 5.0 m/s. How muchs9db5lrf*-m/ 2 eqozo work is required to stop q/*59-oslmz fo2 berdthe 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 cat4 d.j9spma2rgsm 1a f.k c)fvrn44j:r initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s und :r vf4.dt1an 9ss4 .pcgjkfma)2r jm4er 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 .k4oe)lx,cjkfsi, k. gun propels a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the ik kel)cjf ,s k.4o,.xdart 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 componen fl +xylep7wl.3oga5me g) 82ft of 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionlesl8l5xgy wmel+fp.32e ga of)7s 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 :;d,on,ix nz9 cw*ipo g is shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stoppo 9o ,w:n*ix n;cid,zping 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 m,c1 0lrp4/pmxqng : txoved from a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravignprlt0/mp, x :cx 4q1tational 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 anu4v ./mj.4kk;ltlf )l emb8fld rises 2.0 m. If the plane is frictionless, how much wo.v/l44 kl tk; fb lul).jm8fmerk 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 +k i3 i(xg5lvdf 27hby2.0 cm. What is tiib23vkl 7 f+h (yxd5ghe 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 spring constant of 60 N/m. Ho/ox3l-g:mr j*tdg+ da8 lllv /w much potential energy does it store, when stre +dd agom8l/-llr/vlg: 3*jxt tched 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 spring with b;1;e z3 u92zm1 mzw:cyx5l0djiqygva spring constant of 25 N/m0iz1c12dz:g 9mywbym 5l 3;zeu ;xjqv 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 hpbd.n ,-dua+ spring of spring constant 40 N/m from x = 0.20 mua-hnb., dd+p 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 /mo jphz.jwy8 w4yg/7N/m is initially compressed by 3.0 cm. How much work oz8yhg./w 7y /jwjm4pis 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. )c3 oux -6kqf(ngex 3tWhat is the s fk3oe3(-xtqxun)c g6peed of the slier on reaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an inil(0d2gm.k ,mm ch; fpztial speed of 4.0 m/s. Neglecting friction, how fast will she be mo,m;l(h0mzgdm.f cpk2 ving 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 jdq g: txk1r-2inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the verticad g:-q j2xkr1tl 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 g 2rwc w e -kzx1v(9b,4dq0reyhn kocz+q785 hfloor. When it is 0.70 m above the floor, its potential energy exactly equals its kineticxkd9n5rzz,4wkh 1 (rq8e+ v7ywhc0 ego2 -bqc 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, blas y:flt3okkq1: ts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanic3lko1tq y f::kal 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 4vuaf4sp8 l,fwith a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point8 auvffs4l4, p, 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 refxf/z7f*+szem 76q b i54j 8gte d;snrst at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect frictirdnxs8;ftz*e/m7be4 5j6g zsf 7if+ qon, 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 45ew :lj fnt+p+- m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coatfw+ +:- ljnpester 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. 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 wit:in7t (3)th x6zjqs wuh 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 theu:x)q 7( nt3 zjs6tihw 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;ep+)vug-ckf -s k-xh at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from8h 0r7h df 4hl a(vof0;+,v0rm4bz srqvg p-wj the vertical axis and released from rest. What will be its speed at the b(w rvr pq lj8 azdvfbfhrvs;go7, h04m+004h-ottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed horizontalizv xkz;k9 (*u li)e0gjz5r: c spring with spring constant x0u geir ij5kz;)ckl9 :*vz(zof $2.0 \times 10^6 \; N/m$. 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 mnn4( q ,tx*sf.3drfuh /s, slows down her 2000 kg car to stop for a red light. What work is do.ushdqr,*f4n3(xn t fne 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 l3hqr+r6id0nand a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distanr rl3i+h dnq60ce 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 molk93x,m 7tge t 2l:czgving on a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far lk,g: cmx7t2 9lgtz e3will 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-kg3q-wduoyr0:l.jih+ lh e .ts2 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 distance of 10 m, what is the change in its kinowrte-:ih l 0.+qh23jlsuy . detic 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 frodn)*c/m jz xp)8gzq,um rest from the top of a 50-m high slope. If the work done by friction /dcjz8qm )pz)gn , u*xis $-6.0 \times 10^{3} \; J$, 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 is2 9nce utp+;bq 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to ; tu p2nqcbe9+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 f vs7hf+wclzret k+z. q--.9-vnn)kxof a plane inclined at 20e above horizontal. The coefficient of kinetic fri 9nc.swf) n-eztl+-zx.krqv 7+-fhv kction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height ofv j o/xb1e .jrgwi78l( 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction .xrgv/ j1oi7(jw 8bel 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 ener)hx+(tv9jw fv u.m7qjgy when he runs up a flight of stairs 10.0-m hi u(fhvxjt9)v 7.jwqm +gh, 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 velocitt/uj9 hy9mi- q9wv0 rjy of 5.0 m/s. What power must be del90m9hjt 9/rvyq j iuw-ivered 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 6re (v n1fugv,moix1 .are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp 1.e6, mnvfiurvo(x1g = 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 rate of 500 W while riding. How much force dor9b+n cgolo7(a e0 yy;es her foot push with when she is trave;(n+90c oyab y7lregoling 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 in 7.0 s. What is the a 9** 34iw2t cdqcomybpverage power delivered by the engine? (1 hp = 746 4di3coy* t2qw bm*cp 9W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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