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

1#

What is the correct unit of work expressed in SI 0q6ovi8n6sdc 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 motz(s*3,1fydw lnl b93-m :)injfxgyy n ion?

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 againststef rkd2zj4)lr0 s:y.a96wm ,j0lel a stationary brick wall, the amount of work you dzt0.r:syl rdlak s lf9ejw j)4m2e60, o

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 vertica3pi+ (gtd bopr2)cn8f +r(lfe lly and is being held there. How much work is being done in holding the boglind)8 +p(+2r3pt frf( c boex in this position?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a conz) :muuct1z kn8q;y j nxm96l4stant velocity carrying a 10-N object, the amount of wor1nj4lntu:9kz6ucm xz 8ym; ) qk 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 r40il+2y9:be-r lw7 u-; oehsjrb c soaeturned to its original position. If-lsyoo0; bjw i+e-urs:a9lbrc24 h 7e the total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force op04ymhz,xp h-yn9z8;os ; y sacting 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. Compares38 ytpj29w up the sign of the work done by gravity while the ball goes up with the sign of the9y823p uwt pjs 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, dogv.la+ 3 w s-0/i7t9w nhycmrepresents0ml.tyca-n+w7 9 ih/ vdsgwo3

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 representffq 0 vs;f;x5f*obq2;e k2psz s the work done by the ff; f2f;xfs0 2*zpoq;vkqe5bsorce 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 o,,tqmjn.adl r) et ))s9e)eo.tqwx.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 oeip x74of d(88mbvzf7n an object 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 o 6fo m e6cmsj-zn:*:jhbject'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 a 3llw 2/cxhd0,*bfqpst twice the speed of the car. Which statement q 2,/hfsl p3d0blcw*x 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 :sy2ia 2m7 whcfast as car K, and car J has half the mass of car K. The kinetic energy of car J, comy2m2:ah s7c wipared 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 originalgk*; pee6i5t vi -;wjk speed. What is the;i5i *-vgwtjpe6; kk e 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 7fz* 6ntyls yj7o n:y:a speed of 3 m/s and a pebble is moving at a speed of 5 m/s.n 6j7sy 7z:otylyf*n : If both objects have the 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 mass is m p5fc+*ghp geinh fn+3wi xe812n67qloving with speed 4.0 m/s. Both objects encounter the same constant braking force, and n+e5qgih3 f1n 8p6 nfxe2ci*lhp w+7gare 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 you e4 lbkkna8- iy9t5jtn x-v6y0r car in a panic, and skid a certain distance on a straight, level road. If you had b-vl nxjei0 4y y5kna96- kbtt8een 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 an elllcg916/cf n 12kidy):kcjrie iptical orbit. Neglecting any friction effects, what happegcdrki c 2nc9i jkel):1 6/y1fns 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 principlebg okdc68 m1fv1fre9lua9: (a lnt):r.

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 negativ.bc:wzoa3+fd3zrh ,b e 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 height h above the ground. A second oc /skn5kfsm g s,zjku :3ph8w g4h6a*6bject with four times the mass of the first if released from the same height. The potential energy u3h,h:ka 6sfj mz5sg8 w/k*g ks 4p6cnof 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 st:i-5 .ljc8x;gj3nws 6 kadqm uretch 5.0 cm. If ;ic 8a w3.6:uxm -lsqk gd5njjanother 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 aiob3 m1v* 2 -v,esz8dd qvj4au 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 kinefe jen 4l3ayg26 l)1+xvrrtb 5tic energy K, to its potential energy U. 254)1tfg ee+llav3r6ry jxb n

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 hildwab jlg8 v5hrc/s/dz(-1j1 ol.

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 verysk.z wb; -n5m7)oouar heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Whb.kzu oomns 7w) -a5;rich 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 cdm djf1bfc9(t **. etd,j.d m$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation o zg;fi6b.n3 e4yja1qp f mechanical energy for conservative forces1g34 i y nb.p6aqzfe;j.

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 pg7/+ijn ;a1icg5t swtop of a building, through the air (air friction is present), to the ground bigiwapj/; 7sg15+ t ncelow. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Do not ignore air rkm;/f.ch5 kr,l/sfk u. 8 dvlresistance. How much gravitational potential energy did the ball lose?l/v. l8 dkf; ,fhrumk/r.cs5 k

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 gr*7b;ut/ vnpbbrr 11( zb okin(avitational potential energy. Do not ignore air resistance. How mubbob*ku(n 1ib7p /rvnr z (;t1ch 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 conse7 ; 1yxw.f*vulzk:azcrvation 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 isrnc:k3qgh4yq v7 2g ,g

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 exn fmj86s:2f crg-r)p pkoi- 7lpressed 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 powdummcl ( v.to u4:x-i3er?

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 theu.3u:pzhcx) at0rjnw ( 4mdt6 work in one-third the time. To do so, your power output must have bea0ch3d6u xnu tm:4j(t.)z pwren

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 an8znyq1 cp*k* 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 held there. If the o.jpem7wn3kl ; jle 93ybject weighs 90 N, how much work was donm;j7n3ly.p9 kwel j3ee 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 wv3 e+ih:dby8 constant velocity of 0.50 m/s. What is the work done +i vbdwh:83e yby 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 upwar :jswa7f1brt .d with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 5500 N for.:ajfw 7tb s1rce?

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 wia* b 4)e*adkooth a constant force of 5500 N for a distance of d)*b 4kaaoe o*50.0 m. What 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 f*pk36s8jp;(f 2aaqgd pon ae* or a distance of 50.0 m. What is the net ( jfo*pnpa ak;e83a2*qgs dp6 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 vq3x1 b f2sip+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, inclined atgkdns7 ,m+7 mrpt/1hr $30^{\circ}$ 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 surface (assume no frrxw1 jocpc;9;iction), wio;r ;9c p1wxcjth a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6evr7(l+egeqt1)4c8 fusa sw/ -1 show(l7vt s1 8/r+ secweu4efqg) as the force versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph inc; /ob.wuuc.u Fig. 6-1 shows the force versus the object's position. Find the work done when the object mo/.;cc .uuwou bves 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 i i(ki0k/1lg :hy9)w:ikwfn7i:zmwrr n the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 4.0 to 7/l )iywk:znmkfig1 rir::(w ikwh096.0 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 di: wgvkoohwyo1*4 a4xz6 y 5l8grection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the objec8hx:k6*4 g 5gy voayozol1ww4t 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 cart (initi(4y5r+nim vy ially at rest) acros+v ynrm i54(iys a 10 m level surface. What is the final kinetic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart 9 pz o:y;zij*ldc+zl*(initially at rest) across a 10 m level surface. What is thezdoj9y llc ;*z:*zp i+ 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 x ;m0/ +c *x;slzpd 1)(tjjcwls5bnxsmuch work is required to stop the sxj5d1+s;z 0mjc/ cw;p (txnx*lb)l smass?

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 initit 2xxr2yi;ll/ ally moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under thxi;ryll t2/2x e 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 dar6k xat(x qp9.e:w;qgdt. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun,6xat;qdx ge.(9 :qwkp assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and7lg - 7.kwzwrzfy ,+xy a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. Thefx rwlw,z7yyzk-+ g7. cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, striking the haype 7(s o-o8qml oplo7e q-s8m( with a velocity of 60 m/s. It penetrates 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 7.00 m above a floor +gajno)2w )4yk , ywhhto a height of 13.0 m above the floor. What is the change in gravitational potential eny a 2how))+ wjnkhyg4,ergy?

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 inclmrzv.+ed)eu6o /ic k*ined plane. The plane is 4.0 m long and rises 2.0 m. If the pl)zu* /.+ dek6cie vormane 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 spg 7mcja;g-,nf63y6fn9npmg -f vq p8 bring, causes the spring to stretch 2.0 cm. What is the spring conppqa6v3 -gmny87 fb; j f6,9mcf ggnn-stant?

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 ofe9 eh rrqt.drr)y r4em;8n/(o 60 N/m. How much potential energy does it store, when stretchedm;)hr r/qre4ne 9reryto( 8 d. by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompres9 gy*ex aru 2.v+g- rolhq0h2msed spring with a spring constant of 25 N/m by 1oql rmv2 g h*yx+h2aer.9 0g-u0 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 im+thvkv 1:nf0bil6b8)hd f ,constant 40 N/m from x = 0.20 m to 0.25 m? (mfb,if6 vk h:ni1 v80hdtlb )+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 comprezfw8*gi333w y ge qa8issed by 3.0 cm. How much work is required to compress the sprigz ai*ef3yg 8q38wi3wng 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 startss9;ou vx io3)n from rest from the top of a 50-m high slope. What is the speed of the slier on reaching th o;viun9)3sx oe 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 p0v8qjo xol74 *a:mr6p2u 331nt curxwzou b*an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dro2rxjpz8qa p0w b4u67 * cut:3r ox3n*1lvooum pping 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 frictionles8n q 7i+tf9t nfln,iwu)78svzs inclined plane. At the bottom, it has a speev 87ni+fzf sw) nuql9t7, int8d of 9.80 m/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 0.70 m above the floor, its poten1f n) vkhs.f osrf,05jw4wln(tial energy exactly equals its kinetic energy. How fast is it movin h,wn.o 5(w1s0k4 rfsnvjlff)g?

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 10mk:dem3 a3 om1 N, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanicalma1od:m 3 e3mk energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy of 220 J.m uqy3zh;w6jme 0 ;w9g At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point90 mghewy; wqj6;u 3mz, 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 bottoqgi9rt /u 8sh+kfla )-m 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 f l -sga8u/ir9kqht+), which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m aboe 2rahk+*fk7bra l3 1vb2 7y3*qhzbpzve the bottom of a dip (See Fig. 6-2). Neglez lr+h q faz17r kkhbb3e27bp*ay*23vct friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 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 thewx:k qx9f6t;ka,k,l tsb o/w1 bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top 6a1/ wx:qwx tk,9ob;ltkfks ,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 the bottom ofl;6olkb an 2q+ 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 f0t,a2bbzizwbsj6pc px1-1pv3 r 8z+ drom the vertical axis and released from rest. What will be its speed,p281b rzbcp djai-zt0 b v 16p3+sxzw at the bottom 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 hit*ld d8la;,d,gmu ;hcvk8oe/ js an initially uncompressed horizontal spring with spring constant of j k8;,;ldlmhg,edvd/cu*8 ao$2.0 \times 10^6 \; N/m$. 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 2000 kg ca tm1a9 th sxndh x7dx;(wju6.:r to stop for a red light. What work is done by the friction forc x xx1 (9htadjt .wum6n:;dhs7e 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 fsxl x,98+zhha 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 9,f xhshx+8lz 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. Itss qt ;g3v,pxjn-)3 hy e4:pct has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far s,yjpeh 3: ptc-vs4txg3;)qnwill it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg m 30hx 1yj- hgguq8;vhxass on a level surface. The coefficient o uxh0h1xq gj38hy-g;vf 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 kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. If t57an- v5dwsznx2 2 xody9 9nwuhe work dn9duz-n5yxn25 9so v2ax7w d wone by friction is $-6.0 \times 10^{3} \; J$, 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 pwg kt 2 *y0)k,duozv+a 8sqq1qlane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What wqykwd20s ,v*zu)8gq1k tqao +as the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined at 20e above er8m*np6a v ).v4rr bahgy 6b*horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. Whavevb8r)y 6*p hgab4mnra6. *rt will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikes thr9e n:k:x xba/e ground with a velocity of 7.00 m/s. What average force of air fri :re:nx9k /bxaction 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 *axnad6ck2*vj7 u 1zntdbr orm4y8++runs up a flight of stairs 10rzd tu7vjnmo1ar nd2+x+cb *k8ya4*6.0-m high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity of 5.0 m/swtlh *v;1zto i,3kq3t . What power muv3 oh3z1wlk, q; t*ittst 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* dt.pnp i*jg1.0 hp motor that runs for 1.0 hr? (1 hp = 74t p*n1* jpd.gi6 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 does h+r .: ),hfxy68n-d:kok sie nb;ehdfher foot :8; bne .)dsk+e- fhon hy6rdixhf,:kpush 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 7.2 8oa jysxu, +noqem4:z80lgg0 s. What is the average power deliv 8lg0 4x+eu,q o2o8 jz:yamgnsered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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