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

1#

What is the correct unit of work ex nlc-js9x f52 bx,:h:qdbvxr.w*u b+a pressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s$

C. $kg m^{2}/s^2$

D. $kg^2 m/s^2$

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no 3*u xd4sn:/ ibsh(hs imotion?

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 amount of work yo7ln2zx,k4s4*jwch m ju cxk4ljn zm*,sj47wh2 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 t+ay 4y tsk9ev5;n zga.here. How much work is being done in holding theyz.ns+94 v ga;y teka5 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 foaui 1)kbzog3hw ta.-ow:d0 -erward at a constant velocity carrying a 10-N object -t i3:0e)wzogu.1 oaawb-hk d, the amount of work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned to )if lf vr ie6hv;(-mn3its original positionvmnrh3(i; )fei-6l fv. 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 6t(y gq -kgxzqh olj-r09t*5zforce 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. Compare the sign of the work done 4q4r4tq- z)mqcuduw+by gravity while the ball goes up with the sign of u cqd4)+w 4z4qrtu-mq the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) graph, represents+l*uhr:r1pvtbi 0 ,5u ya7rcgvt ur7 :rh5b c0pgu+y1il,*ar

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 positqy:pi(9iomo/ ion (F vs. x), what represents the work done by the force9/op i:yqomi( 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 objofk 0p-t ; od:nyhy3/rect'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 hvs cd51 o-ha nb//cu5-.tmulobject is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the obj/ *jh j-q mmoo npju1,.3n0stlect'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 speegpz92ds8wh tjp 3(quwb2- ;7(zr ezlmd of the car. Which statement is true about the truckjb(e( 37zzth s9mwwlrz8pqgu -22 d;p'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, an( sb/p,3zhze bd car J has half the mass of car K. The kinetic energy of ,e zsz( bp3bh/car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its origiveb/ 6-(*xtr.lzx *qmq mj1l vnal speed. What is the ratio of the final kinetim*z(qv-jt q .e 6l1/vmb rx*xlc 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 3 m/s and a pebble is moving at a speed of 5 m/ss*nyx-0jdj *x . If both objects have j-*0ydjxxs * nthe same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg marn99odqt 3 t:hyx6uc7ymu5v) g*enw 1ss is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Whichm7thngody 9 qr)6vunx5tw 19c* 3yue: 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 y 8/)u9,ufw ;goi*-ec qzohov6 0szwxuour car in a panic, and skid a certain distance on a stw,6 oow0seuu cvig)/ zx ;qzo9hu f8-*raight, 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 a0nqdu)+/fe9a p em128bcdae i:epw:tn elliptical orbit. Neglecting any friction effects, what u +92mnaibq 8w::te/a0f ed1 cd)p epehappens 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 p oi r0:3hz; blvc7ht4erinciple.

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 6v;xk/ 8iiw8v 9gc facsystem to have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a hei.oy7ekiowdd5.wlcz ( ee 3h16ght h above the ground. A second object with four times the mass of the first if released from the same height.z 3 5yk1.de6.7(cleodoewiwh 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 thez6s bu6)rwl 8cwqr.:k end of a spring causes it to stretch 5.0 cm. If anothe)c6szu.8lrr:wk6bw q r 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 p 7lk;wcd *skp:k4ss5 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 t8nwq-b5( w1spka7 em6l rw4boree. Compare its kinetic energy K, to its potential energyow4 qm n 6 skbb7ar5p(lw8w-e1 U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving up a hill. 3- :wdco;zose 3mo/k*xr pf9w

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 h eawb1q+o.)/l w /ps0lmjcsf+eavy object are sliding with equal speeds along a level fr/ jb asm0)+.lwwqpo c1+fe/lsictionless surface. They both slide up the same frictionless hill. Which rises to a greater height?

A. The heavy object, because it has greater kinetic energy.

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses nr qpiqy38-4 + +vwg5 unf1ujr$m_{1}$ 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 energy for conservar4-f3dbgcu7u/rz)0 2zf aes gtive forces.fucz r 7d/a0 -2gre3fsgzu)4b

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 thej(g/-bb3 39xy cw5c5ellclz k air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare tox w cl(le 3/59j bkb5ly3gccz- the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gaisp)b6 szp4)go ns 30 J of kinetic energy. Do not ignore air resistance. Hpp4s) bg s)zo6ow 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 anhczyhz7g-d, q , x7.q1na4dj cd loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gain?g1a-n q4 zhj,,.xh7 ydcqcdz7

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 enerknci)5n zew7k9m(md: r. b:e ngy.

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-pww/ 59u7- e tifhosr

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 rkm8kf69 *m myvw: y)gof power expressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s^2$

C. $kg m^{2}/s^3$

D. $kg^2 m/s^2$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not auz;* v3s4wiom yr 0w7ahgs. ;u 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 the timei (l,t.cx4g 4rmyeh8p. To do so,p .( myglci8,44xtr he your power 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 iz /3pdr5m0y +ml6cp rd3:on hat a constant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and lo)2ji qx5w4uu*5cxrnyl- d/held there. If the object weighs 90 N, how much woxi4ju5c2lwny-)u 5d*rlo q x/ rk 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 conshn+x .i-opa0xtant velocity of 0.50 m/s. What is the work done by the weighipn0+xaoh- x. t 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 constw dmij- :rzrif0r p 8+/h,x*szant force of 5500 N for a distance of 50.0 m. What is/h iwzsmjr-,8fi xpr+ z:0*r d 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 upwarprmu:j9b9lreu ktwvp h -d4cm8h7 )ino,.h; (d with a constant force of 5500 N for a distance of 50.0 m. u8 mohmk c4l j)ipd7(h9,t hnr:r9.p-e;wvubWhat is the work done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a d kip35lv 1wvd)istance of 50.0 m. What is the net work dop1)lv5d ki3vwne 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 pulledsuxf+(4.1lol cnt: 2, 4y qa njtgmz;w 6.0 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 m6x03-dk wgx pq vtux)elm7, g0x)q2ezjs-rk 9 down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sar**we(cy opq 9d sb6 st.14zotmah in a sled on an icy surface (assume no friction), with a force of 604tps c*my ewt b1 6soz(*q9o.d.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 inddk9k / uy891vucj( Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 tkuv1y /(u89d jk 9incdo 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-1 yzr4m8u qat of the force. The graph in Fig. 6-1 shows the force versus the oz t18m4r y-auqbject's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of toddl7 9hlpeb*5r3c8 z he force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object mo5dc9lez7*prdhb8 3o lves 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 8l,gomew6:r10 yhazgev nve/,7co 2nFig. 6-1 shows the force versus the object's position. : wnmo/h8,,gye avocege12 0zn67 rvlFind 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-kg wckwv7us9aw7h7f6(o cart (initially at rest) across a 10 m level surface. What is the final kiouc a9 (hsk7w 7wwvf67netic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at r-przh-cyr(5k h -d2gt est) across a 10 m level surface. What is the final speed of the gyk2p- r hd5-z-crth(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 moving5toquwska h6 x )i .8ky,c)ct* with a speed of 5.0 m/s. How much work is required to stop the mass? 5s t,xckt6hq)y)ck.uio wa8*

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 2b7aayp+7.m s icbv0kniwd; 495 m/s, what distance is required to sad;pybsi.9mcb0w7a+ n vik74top a car moving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is cocked by exerting a force o;4hlo 7qit ej+f 20 N over a distance of 5.0 cm. With what speed will thitq 7h+4; eojle dart 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 comx5d*vi9g d 4 ogosfdd)mdr715ponent of 80 N and a vertical component of 60 N. The force is app9 do5* 1dg s7gord5v)dixm f4dlied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g,dv; 2iz:uqx8nsh i63yjy 8qn is shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetratd8vsj ;3h:nuqiyx y, 62 z8niqes a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.0i peu2 0ff (h.2ag-tbd0 m above a floor to a height of 13.0 m above the floor. What is the change in gravitatdugfh pi 2t.0a(b f-e2ional 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 incly2k) -9wgy0 pi2k0vfsum y,skined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done by theus9y k2-ygmkkf0y,sw0v pi)2 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 tow- v z- wb*do;;ytcfl5 stretch 2.0 cm. What is the spz -; fy ;dbwv-5wlto*cring 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. How much potentia0ici; wm5wiu/l energy does it store, when stre5i u0w;/c iwmitched 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 i,+st++u 7- jt9ibyk 8owi ewxhnitially uncompressed spring with a spring con-htwo9u b7skx t+8,wy +je+ iistant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring conswrd6d4 ,706zijnpqf x tant 40 N/m from x = 0.20 m to xprw ,j z7 n06dq6fi4d0.25 m? (Assume the unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3.0 cm. (zu 3jhc,bx b) How much work is required to compress the spring an additional 4.0 cm?j(cbbz ),ux h3

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 fqk3pauuu3 zyw.1p 9 8y+w+qta 50-m high slope. What is the speed of the skier3.pf+ w+y3z8pkty uqu aw1q9u 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 ,x.fff ugb.9mthe top of a hill with an initial speed of 4.0 m/s. Neglectingf .bmgf,9u.x f friction, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless incb ds2v b4di-/ h6dizv*lined plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical hei/vbi6 h-d 2si4v*bzddght 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,1su m.vq;l w5vw:aw .r its potential energy exactly equals its kinetic energy. wl;mr. w5us.w:q 1vva 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 1 csz0+7 .s+y2svzoqju0 N, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical7 uy qs sv+jzz+20o.cs 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 massi e b/gcj+r k5/c:vern0l2oe- m leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory,vn:ebe0rrcj5g eio - c 2//kl+ 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 kxhu9da/ m l:5bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller d mk/h5xua:l9 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 (zxav2a(j 2fhk;o2:cnpc;wn 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 thh;2fjc; oanazk2(xw(n :cvp2e 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 opiyjnw:*-q.61 w:mqu ue ;ws c(lmmq/:.jqbvf a dip with a speed of 6 bwmw:wj:(luuj;q/:y s mq-eq. pin.cmq v* 125 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the5vnjvvjdfql 2rvf13, 65*p bol70klw 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(qg*enrwb3 ,ta x1 wk36wwpgo o*;e3e pulled 0.16 m away from the vertical axis and released from rest. Whatergww;*ekqa*gwop1t33bn(6 ,3w xoe will be its speed at the bottom of its swing?

A. 0.2154 m/s

B. 0.574 m/s

C. 0.861 m/s

D. 0.718 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 initiallqrf(dp8qyk(t ::ud,4. m/b 1hm lllppy uncompressed horizontal spring withlq d,lm: y(hqk81blturppf( d:4/ .pm spring 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 dgyq gpj:e i1k;9fh+i7own her 2000 kg car to stop for a red light. e gifq;1 :yk9+jg7hip What work is done 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 objectow,vv8s:6dl ;p lr5s r and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what dista68ol: rpl5sv ;,vrw dsnce 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 J of kinea b+c;n cmy*n)tic energy. The *c n byn+;amc)friction 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 t brqz xu3;cq34o a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its c;3rqzbux34 q 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 m /i f+vyaj 1e4srx29e50-m high slope. If the work done by friction mr9fsa2iex+y 1e4/vj 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 4.0 m long7oj6i( jkse ;y and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What yj (jsk7 ;o6eiwas 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 iws d7orj.)i/ hnclined at 20e above horizori7doh.w/js) ntal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along 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 droppe9 2abu ugl1g( c2nfu4hd from a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air frictionna(4h29ubu f 1gl cu2g 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 flsam945, e pexq)h6c djight of stairs 10.0-m9xd 5ah, )46semqepcj 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 need:l ouf3utw a +,y6i4nj4r)vfpss 2ocl+ *xbc.ed to move an object with a constant velocity of 5.0 m/s. Wlb ysro3uw,4 o 4u ix+lt.c)+ *ps 6vjf:fn2achat power must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs 3meho.eqx 0n8 for 1.0 hr? (1 hp =e8m hoqxe n0.3 746 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 forceera5 wbdt78f icyp),0 does her foot push with whef ar pd 70w)i5ybte,8cn she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/.d tcw 7 g3+e9izxbt*o-fuyz+s in 7.0 s. What is the average power de.*b - g++37ozeixtud 9wctzf ylivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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