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

1#

What is the correct unit of work expressed i l )s5jriejcq;n3t748 mkgv+un 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 tk4hamyoo.4k;k 2r) ea tm ;7fbhere is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary vop .efc .9y:zbrick wall, the amount of work yofc9ze:.o vyp. 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 verticalm6ci+3z9yo ge ly and is being held there. How much work is being done in holding the box in this c9z m6iye+3o gposition?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constant va ek2i**+6aq qh le+ooelocity carrying a 10-N objecte oo2ai +k +leq*h6*aq, 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 3 uyud28yw v(x o2z4 rh(2ukcqrruw-9its original position. If the totz2d(o uy 4uc9wvry u2h8q3(x wukrr2-al 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 obj.if:)nm sgz 5 axsg33kect 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 by gravity whilo .ix pimw osnyqpr69d003v-p -t.9zo e the ball goes up with t- ov q -. st0i3wdppmp6in99oo0xr. yzhe 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 versu- k6nykherk 6 2 xqyjur458d3cs position (F vs. x) graph, represents 8ryc6kuhqk xj-e nr5y4k36 2d

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 t;.c guf. nc2blhe work done by the forcgnu2;bl.c cf.e 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 object's kinetict7gm d 9 qrf8z, c8rle:olwll,d/z*j* energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then the object's kinetdzn eq13,4bz-h;t u0d 5egr iric 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 anr,rq 5sae5;sv1 rxv1.(fruxyyk (an8 object is zero, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice asx6xlgd wb -(747 lknfzz,a 7xr much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of t 6ndb-x7(l4f7r glza, k7 xxwzhe 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 chc)l. 2k9 j;cymtpn0war K, and car J has half the mass of car K. The kinetic energy of car J, compared cm ct)2pjwn9.h;k l0yto 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 original speed. W0 wc1 gv)xj37gckinl d +tv.7lhat is the ratio of the final kinetic x+)t j3v7civgcll7wgn .0kd1 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 ii9p* 1a28 fa s7vf - z)afrj9g4mmtssa speed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, imv9 41ssat)a8f- jfs2p9f g7r*mzia 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 moving with. .j3xm3c; wxtbn:rl5 9iyo dm speed 4.0 m/s. Both objects encom.3w 9d:j;5b t3l x.myn ocirxunter the same constant braking 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 hrcuo9jw 1* 8 yi63dgiin a panic, and skid a certain distance on a straight, level road. If you had been traveling twice io61jiwg*cr hyu89 3das 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 z-awv3cu)fc-. Neglecting any friction effects, what happens tc- )-va3ucfzw o 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 prin 9 j1b 1w4h)sv qfsukwk36bkb)ciple.

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 hav1lk 8 g*g;xrid2+oj *x.oiuxk e 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 height h above the ground. os7,vh 3hxfu0/h p 4xmA second object with four times the mass of the first if released fro 7vhm fpxx,0 hs43hou/m the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it to stretch 5)p 1wnrx6(in y.0 cm. If another 0.200-kg mass is added to the sp1(n)6wn xirp yring, 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 ,j;u)br e awok wb;*lu oi+qve- 74z.la 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 energy K, to its potentu( gcxo 51: 1(xzuj6i7 *o hm/poe8qatmgy5owial energyeu:op 1/o17z5 86ughatcywi*m5xgq xo(j m( o 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 hi:yjt;jhu)qutf4 (mshrb*s- 5 ll.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are sliding with eqgu*(jj dylm,l6i) r1 qual speeds along a leve*6 ),gu(d lm1qyrljjil frictionless 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 f j3(y3 /zz+eon5kl-tt*y8kql,ftqx $m_{1}$ 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 consc7sfq c -;sr.5lfsi+rervation of mechanical energy for conservative forces.cfsrc -r+l; .75i fssq

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, through the x89 k2w ust/gvair (air friction is present), tsg2 k/uvt wx89o the ground below. 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+ (wgicv7o1 v:smv 3zyra*rp1 and gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the ball svawc1 3 7ry+v:pv*mogir (1zlose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational potential l6.nphx* 0g2rc n oxi +ak8 g)usju,h2energy. Do not ignore air resistance. How much kinetic energy did the ball gain?+a ph r x lnjgc*ugsk6u028i2 xh,.)no

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 conserkoa0 pu*bso9 /vation 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 is6jg9hsn gwy* ri) 2x:n

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power expressed in SI uni/-vvr(m,y qc8 qu8cxxwv (-lb ts?

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 ov,w*-qiwfo )kk+jp an8f(j18 w e(ij nf 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, y4o a 0,qykacg-orojzt;9q4 h(ou did 3 times the work in one-third the time. To do so, your power oo4( 0-jy;ch,zoq ot9kr a4q gautput 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, the car's enginq8uui; h*fwey 6p gv)72 :ebmhqi+,gee 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 2ibo0 7(t1m 4b5ryxhmu.0 m and held there. If the object weighs 90 N, howmu(txy 0 mh7rib1ob54 much work 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 gzdiii ud 3go 5x5n zj7e34j15distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the e4z5i 7dd1gzxnioijug j 3553 work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator iskmr8tyg + 9cf)lg-,hp pulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 5500 N fogc89+ lm ktyhpr -)f,grce?

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 upwari2ur7yy7qz 8 nd with a constant force of 5500 N for a distance of 50.0 m. What is thein7ru 7zyyq82 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 m2p/ q ;+z5yurbely .a)td-rp t.h1 tfupward with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the elevahypl uf2.t -dmqbz)+p; e .5/tayrr1t tor?

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 8ig )py2c-eh0t c ds/dup 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 slid hejo-.zpj/o..d(j k) a9l qyxes 8.0 m down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled+ayddcd6qc*+ tovl k.50mn w7v5ajz+ on an icy surface (assume no frict0.d 5av6*7dcmc+ko y 5alw+ j +nqdzvtion), with a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. 9u d+lstggo2(k 0dtm: The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves uggld0 t(:s dm+ko9t2from 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 forcew6d ou+k2sn ,h. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object movesud k+s62 h,now 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 thqp 8ef sevt1/2c(az k8e direction of the force. The graph in Fig. 6-1 shows the force versus the kzqf8/vec2 pt as1e8( object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. *lovxzn 1gpn *23ces: The graph in Fig. 6-1 shows the force verlgp:co*vnz s3e*x1n2sus the object's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg c/r*2 1a 3sjr:r pmsnmqart (initially at rest) across a 10 m level surface. What is the final kinetic enernr:qr1 sr /sm*am3jp2gy 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 ,63rvit7v ysf17lk ks .pyz0n55-kg cart (initially at rest) across a 10 m level surface. What is the final speed of t6 r 0 t1s,vkfyn73i zykv7.splhe 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 spe(98 :wwas /2hth agyaxed of 5.0 m/s. How much work is required to stop (w8/a hat xsh:2agwy9the 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 ar 3xy2(y7 h wvudkv.a, car initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s undvu3h( 7k w y.vxy,rda2er 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 bw4f ejixl+p 41dyxl+1 y exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, id 1 4l+1 xlwpe+4fjxyassuming 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 and a vertical component iek0acs/q 8fxb15y tf3ejb9 +of 60 N. The force is applied 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 kine y9 tcf s kqbf8+3b/e1jexi5a0tic 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 jz4 cov-j3(kwbale of hay, striking the hay with a velocity of 60 mjcvzw-ok3j4( /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 hj*udsu6 g e1w/q8br 5gg kh*/deight of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravit sb1d5*wugkj rqgh u//*edg6 8ational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined p /l:n x 3s+pd24lsdajl2cf3aalane. The plane is 4.0 m long and rises 2.0 m. al 23fl xndssp4 + 32jcaa:ld/ 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 stretch 2.0 cmw vr3ho+bohfzxqr f9 04y8 3a6unbr68 . What is the spring consta xf wv3rb4 h3yu+b 8zrno0a6r6f8oh9qnt?

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 potenp,vg.vqui y 9l.6j-rdtial energy does it s 9lu,-qd .yg.6 vprvjitore, when 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 1n9tp ;6/p xg1krocae an initially uncompressed spring with a spring constano prnc9/pk;ge6a 1x t1t 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 stretch1 x)8 d dbi6 g9dzk/azkr*if7w a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at9*gd71d)b z r6zk8x /ad kwifi 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 spri-(hslg1e p xupcl-e5hk86: sqng constant of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an additional 4.0 xe:(kpq hp6s1shgl u-c85le -cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the topge) pu3z.h4./nlmxyg4 oa u t0 of a 50-m high slope. What is the speed of thx .z.hpg4g)e o/lytu mu0 n3a4e skier on reaching the bottom of the slope? (neglect friction)

A. 22 m/s

B. 31 m/s

C. 38 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off thfzn eu4 d *to2es3em.3e top of a hill with an initial speed of 4.0 m/see 3.zo2d 3m4ef* stnu. Neglecting 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 .db m. :2u6kujpml2mla frictionless inclined plane. At the bottom, it has a speed of6j2udm 2blm. :l up.mk 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 potent,ix 6h /j*rhxfial energy ir6 *x,fjhh/xexactly equals its kinetic energy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground level wi0jbh00 vq3espa ch)z 1th a kinetic energy of 40 J. At the exact top of its trajectory, its tot p hcah3zq) 1jve000bsal mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy h7bg 8mqsc2vz(umj/w/d * o:x of 220 J. At the highest point in its trajectw*mbo/um:2 /sj v qx(8dz h7cgory, 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 pointxt18rl s 85hs5jay mjg a2oo3w/um(.g 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of 8a21jhxr.yg5umsm5 o o a/(3ws tg8jl the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

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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 jvt14782 rafldesx8 bat a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the rolleds7a8e4 rbj2t f8x1lvr 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 .ad sx vw.0xr+m above the bottom of a dip with a speed of 25 mdw0.xsra. v+ x/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 spfsut 6g b-zu(z,w c9;yeed 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 0.18 m away from the vertical azq25 3hxay:q vxis and released from rest. What will be its sph3z aq:v y52qxeed at the bottom of its swing?

A. 0.243 m/s

B. 0.649 m/s

C. 0.973 m/s

D. 0.811 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 25lx g4+ e(rfor/ m/s hits an initially uncompressed horizontal spring with sprin4gl (roxr+/feg 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, s5l afearun i:dmb60 rl7w7 -xo4 c8i9wlows down her 2000 kg car to stop for a red light. What work is done by the fricw78-lowm r74i 9canu5b6fdx :al0e r ition force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horizontal surface mwn+xh5w:t0w + v+d+c f-lyuois 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a st++wy+-t ucwf nlw:v5xod+ m0hop?

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 sur :eb;r trsim.)face. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far :brte ;).si mrwill 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 horizontall/: ln2i)w q9kjbcxv/p y to a 2.0-kg mass on a level surface. The coefficient of kinn9/ ) ic/ lkxw2jqvpb:etic 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 ofyonv p /a(zk n 4(2v/i8ctzl(u a 50-m high slope. If the work done by fz(acvoz u /tlnp8(/ 2ni(ykv4 riction 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 push6 4)24 tgqhn1nlfeemxed up an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work6ml4hq1 g fenntx)42 e to get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a 4( ),nwvl ywlkplane inclined at 20e above horizontal. Theyw vl( ,k4n)lw 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 dropped from a height v5k 2 o.dim.xrof 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on v.rx5io 2dm.kit 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 fligh29q1tm;fg*c3ui;o lpn rq0 xst of stairs 10.0-m higt o2n;lxgs c *m1ur;qf0qi3p 9h, 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 movm,wvtam7* y 9oe an object with a constant velocity of 5.0 m/s. What power a9mmwy7 vt,* omust 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 energyb..0 e gjxo/l:1sq6dh n+i yxv are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 76s: +io.b0d ve yxx.h ngl1jq/46 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 forcx(6mdyxjq+/ z-/i*)fbm y67 i csoprce does her foot push with when she is traveling am6 zi-mb+sy/ c6o)* i q/ydpj7c xxr(ft 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. 27j8oz(xgs dkWhat is the average power delivereos27kz(dg xj8 d by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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