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

1#

What is the correct unit of 9isau pgkow 7g,lj 657j *lb/mwork expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no nb6wxm574wyxr6li/p up r2 ,rit.io+ 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 amount of workc,084(jt5k tpc a wyxm yo8xm a5pwt0ctkj(y4 c,u 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 d0u6ccf. hl 6cheld there. How much wor 0cchd 6c.f6luk is being done in holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward a8(bd oawzqtm 3c +5;jft a constant velocity carrying a 10-N object, the amount of worq5 tmfoz wjc(+da;3b8 k 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 tolix/;zwpz7xj ;8jx e( its original position. If the tot8pijxz/x;( ew jl7x;zal 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 on an obju yps- el pz:;lq62d0pect 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. h, ej: 2v,1gratate jmy3a 0-ngv2z(m Compare the sign of the work done by gravity while the ballrm :(je z-2 atn31t2g,a g,ejamh0y vv goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus posiayj0;t-6 oerd9doibe4h , hi6tion (F vs. x) graph, representsj,od6ahh db yioie;r 6 t4-09e

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the wor-phv) u*9si gf/gqnj:e px 6w3k done by t)6xp *3v/gsq j f:gw9phne-uihe force 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 objec1v9i hw01lt llw-+xbmt'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 i-fyf8g 3 dv qxnce2f*(s 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 object'sm5nmv fq 3+t7l 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 mucc 3i (uv1lahz*h as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic eneral*iczu 1h3(vgy 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, andhtg 5nkm)6vq 5,c2tls car J has half the mass of car K. The kinetic energy of car 5gktv2t ,c sm)65nhlq 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 oi7n5jclc )igt0x70w half of its original speed. What is l7x7 5iotgcc n0 j)i0wthe ratio of the final kinetic energy to the initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed ofu3pdg 2+u5g cfz*3)gta+ dpmj 5 m/s. If both objects have the same kinetd+z j253 d3 )+p pgfgcmgu*autic 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 mass is m0,mu ,n1b*y k*vaiysdoving with speed 4.0 m/s. Both objects encounter the same constant bd,bma,v*ky1*0s iyu nraking force, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skiduue )b,5wwrmy.qh+ uc ijb0;+ a certain distance on a straight, level road. If you had been traveling t,ibcuj)wr 0h+ muqu;5we +b.ywice 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 an elliptical orbit. Neglecti b j9zoop.j8ixp3-pyc7 -jkb3ng any friction effects, what happens to pz 3. -bjyxpkic38 o9-opjj7bthe 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 y7 1,6*nbkvg d9fygqhprinciple.

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 p8dj,/p+ ezycif t:dp+otential 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-pfz 3jbx l ;kb;k1jwv4hn8 i6 rest a height h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second object com13fz -xw4 ph bvbk jj6;n;8iklpared 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 5m qa8h) 1pkmnf,f n4)v.0 cm. If another 0.200-kg mass is)4fmapv m )k,81qnn fh 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 energfmznb) nb .-5yy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic enenb s :y+ 0w:lrryv.sb0rgy K, to its potential enerswv : 0:0nr+lb ybr.ysgy 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 aiprywy5/w o e1ze8t)tt286 )( anwmang v z3-y 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 objectuigx:,g9v s:+*zsp y -4dbq/s bqanp( and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the sameysq( - uq*a/4gxv s+:bp,p: g9 ibsdnz 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 zv+o yg p,z a7*il:ykt:l/yp 1vea3)l$m_{1}$ 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 conservativebq:hm wu .):itzv6k8 r forces.bk :r:w8uh)qtvm i6z.

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 o4 yf2f:a*b da8+,:fpf3cxg*mfq j joof a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the xjfff:3m dcq482 *b: afo *fapgyj+,opotential 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 kin2* xv6iwt8rk/ k/ h(hyxr57ehp:u msyetic energy. Do not ignore air resistance. How much gravitational potentiyuh*t 2/8mv 7hsyie( x/rk rw6p: hk5xal 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 potentia xhewy r6:*5lk;7 es2tjf1at sl energy. Do not ignore air resistany 2ekwhr71;6ejsst:a5l*f t xce. 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 of energs ph*ggea 0ejxz iz7j)z+;xruc n*.6/y.

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 isz do0/gswk3mc+fo3+m 0r z(wq

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 expbw1x7mqo; f h3ressed 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 a unit of power?x2o3 s j3p0s/qupzsk5

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 9m vqeo6/1,l cn mnj5o 8yoby1in one-third the time. To do so, your power/n j obn11ql ym5e8,6ovm9y co output must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, th;u4( szv 4kpnae 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 x6h)4gcktfc4d-y/vothere. If the object weighs 90 N, how much work was done in x yvdf4gt4 c/-)k6hoclifting 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 physipyqxfu4/ 8 z u-:yr9fq+, cih1+vzqx v18 fbtfcs book up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by tbz1:y zi fp1/ cth8+,u9qfq-4x8v fxuvr fy+ qhe 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 foruoog dpvr+xh,q4( uki;hr18 ( ce of 5500 N for a distance of 5 8ro (ikr puhxuhd41o+qv;,g (0.0 m. 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 distawjv7aozste v qvk;/tunw z1:h5;,44dnce of 50.0 m. What is the work done by the weight ofz,t:1;vqa t;e5 4 sv7jv/zw nuohw4d k 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 f79idjinor7 gll,v7:t lh/+uhorce of 5500 N for a distance of 50.0 m. Wiri:un/ tdvl,77 olgh9l+7jhhat 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 mt54ho1no wp fv 4pbo,3 up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp oq/ajc7s1dn 5, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy surfacex5nour448i(9 gj hq8md v6muj (assume no friction), with a for6n84v5m8 jrjm u u(hixg 9q4odce 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 , y/qk +askyl)0w pf0adirection 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 0 tokaywl0,p+ys0q/)fka 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 -u kvw9 j-o2y6 (nlbdkof 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 2.0 to 4.09ovb ykkd nj2l-6(-wu m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The nrdnjs1jn(b506uv 7x (jp 3k+f*xpz agraph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves fro6d*p( 1 (n k5nsjpn abuv f+jxrj7x3z0m 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 thesf .eor+*ns9sxvb6w, force. The graph in Fig. 6-1 shows the force versus the object's position. Find the w, 6x rbvso9s* fn+es.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 mmt2- :n37 qlag3iau.2ag( bzphw rl7move a 55-kg cart (initially at rest) across a 10 m level surface. What l3 3ha(p.at a-7:2gq27i ruzlmmnwgb 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 5s0: c:cqsxk :c5-kg cart (initially at rest) across a 10 m level surfacec xsk:sc :0qc:. 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 jhvn;r )gaq-f+ d yjx9(nj t ,c6s3fw7of 5.0 m/s. How much work is required to stop 7 fjf jx,qt) -n 6h 93dnca(r;sgyw+jvthe 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/sh c:-m; sn-p9 haycd 8nkp5ts), what distance is required s5mahkyc9hc-:) ;t n- np8psdto stop 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 isn .jfr (4,4:6.tctsmgyty cnn cocked by exerting a force of 20 N over a distance of 5.0 cm. With whatr m y4n,ftjtsncg.(.n:y 4tc6 speed will the 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 horizo2ejd+re-:, mjq ppjqz2. kkz06bxo (dntal component of 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from xjd m,+q0(p job2: e6jqd2zkr.p-zek rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, striking tj,xghg(k/2of.eo uh4 m .n)fubt tk0, he hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. hn.fbk4 .o0,egjtu()ou,t / mkhf gx2 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 hexa0y1dvk8t :gc* i2r bight of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in:t0v8*gdr xa ckyi1b 2 gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an in +s2uj yhl-w/oclined plane. The plane is 4.0 m long and rises 2.0 mju / lwoh-ys2+. If the plane is 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 strncp9 ) jnd)u2(tr /ubgetch 2.0 cm. What is t uub/dcj2np)gn 9(t) rhe 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. How much potenuhsok*j6k- e + mq7(yftial energy does it store, wheo(yq kumks*e -h7+j f6n stretched by 1.0 cm?

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed spring wdakwv 6: 0;b3duuo8s aith a spring constant of 25 N/m b: u;ksvo 3ud6a8wbad0y 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 * )xcbbq+f r4ostretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstrc4bx *f +o)rbqetched 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 c*ujr7x-n( x glonstant of 15 N/m is initially compressed by 3.0 cm. How much work is required to comp7lgrx u*nj(x -ress 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 th/4wx ch1evpnp+w/q +t .hst6d e top of a 50-m high slope. What is the speed of the skier on reachin 4h6p+n/h/ed .xp tq+wscvw1tg 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 withy(b qot38/zzd an initial speed of 4.0 m/s. Neglecting friction, how fast wi3yzotq/b(8d zll 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 frictionlerp8 4hmr nn9nhq/)l8 i3rm qrqi5*en4u+1ngsss inclined plane. At the bottom, it has a speed of 9.80 mm) 4n8gh8q5en r rnq3+hln rn9pmir/iq1su *4/s. What 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.j,n*1z js f .l ;qtrhh-j*tk4d70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is ih hrl j *f*q.ktt4sj,1-nzj;dt 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 lemw (c4 eu7mo0rvel with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what 0o cr(mmwu47e 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 ofw/ l4/ gqixumw0; eyb5 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it riseuqw0e/ m/4w ;ilxby g5?

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 6ph397lfms m,djait 0 point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed ofj i96dls,0fpm 7tm ha3 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 w6 4 owpa5iz ri4-eop 7f0yo9vx -war8gx0o; za point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is9z 7i-4vw6w4ir80pog5a e owzr;xoy xo -0apf 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 with areyg0wk,/1n6 w dh dn3 speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the ,306rkwh dng/we yd1n 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 speelnx57qkh4q+ t3y ;kwmme7.wjd 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 pulled 0.16 m away froix7 yuza 7+olts3+ns ;m the vertical axis and released from rest. What will be its sps iu+x7 o;yn+ltas37 zeed 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 initially uncompressed horizowrg4 .ikxu5aa jv*1.6wk6qa nntal spring with 16wrqaj4iawv* uka6 .xgn 5k.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 down her 200*x-qa9 rk(z pyf9k w /sj0y*rn0 kg car to stop for a red light. What work i jaq *r9 kpfks*(/x0w 9ynryz-s 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-0 b2ij4fpvizarpr+2p3h. hs object and a horizontal surface is 50.0 N 40jrh+s.3pp vip rhz22ibf-a. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on aa8.f*3ovr k sk rough, level surface. It has 24 J of kinetic energy. The friction force on it is 8 rs3okkva*. fa 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/;k ;:jt pawz of4m-os7j mk1r to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change jo;orftzwmks:aj1 p-m/ k;47 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 ayrl, d,8o q7yh 50-m high slope. If the work done by friction y,7ryl8qdh o,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 long and risesq -d6yz/zyt.d 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude o-d .dq/y6yztzf 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.o2 sod46,1y/jarpoyiuvg gj 1y. c7l 20e above horizontal. The coefficient of kso .v /prgy1cjlj o,7u24godiay16. yinetic 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 dropped from a height of 10.0 m, qj 69pos;t:tuc9r9vi and strikes the ground with a velocity of 7.00 m/s. What averagutqv6 9t coj9pis;r :9e force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a flight of stairs:m : +k, bivn1jecj4bx 10.0-m high, inb1 x:mcji4+ebn:vkj,
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 fr;2ut4g1 6azxjdd)m move an object with a constant velocity of 5.0 m/s. What power must be delivered to the object by the f;14ugx62d d ar)mzt jforce?

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 usnx4v/ 2 nm6 ,zup8mfthat runs for 1.0 hr? (1 hp = 746 mn s,/86xu fz4num2vpW)

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. ganek/6 0d6qoqtl 0(yHow much force does her ol y6(0dk6q/ag 0etq nfoot push with when she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is the aver2 ibo ran-vp). tt*dkc 0ge::aage power deliv)a-.t:*t0p vobrg:ni 2eac d kered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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