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

1#

What is the correct unit h2u wyga:o*3a of work 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 tf : k:e7no5vl49yl asthere 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 statb-0bxs qhb cz x6v+22rionary brick wall, the amount of work you 02czx-+rx6hb2vbq bs 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 beint3q+) vy e-os*ds9qi+ 3kv cb9ktm aj.g held there. How much work is being done in holding thet 3o-d9bs3qjsk*+vkiy q.at v9)me + c 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 at a constant velocity carrying l b5a)zmpndsw8 pdn9wdr;3/) a 10-N object, the amount of work yoa;w3n)mlbp 8r59 /wnzdp)s dd u 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 retur 1)sk6:8scerkn mlb) rned to its original position. If the total weight is 30 N, how much work wasrmb k18lr c es))kns:6 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 object do work on the ob3ia1 fe3nh ve6ject?

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.6nr2 r+j ds-fd Compare the sign of the work done by gravity while the ball goes up with the sign of the work + r6frj-2 sdnddone 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, ona+p n02jv:e:-qbct ,se ( hpte a Force versus position (F vs. x) graph, representscqa2jpp,bt0 esv te:(neh-:+

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),tcikrvc d8:6 q+0jfh:4j n 1dx what represents the work done by the force F?14xj+vnrk ddht8q fcjc:: 06i

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 objecp.nh,w9o (suexf3dr5/d k + vat's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then th rh:0t/pivwdr45t1ivbwoe;fl8 5 v f- e 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's kineticx17xthm 8*kps8*suqbxnwxgf11-t, i 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, aea 8abjtox; ( cz y07fa7q+x+ 1bken 87i0smkqnd is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of t1 fo0z0s(eakx8nayb7 qm78+cqexikb jt7 a;+ he car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of car K. The k0orbp hgavjabw/g 0eqb -8;8)inetic energy of car J, obv08gphb) / eg0b8; arqw-jacompared 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 originr wstf -a) j2a1p0t(w(j ov)syal speed. What is the ratio of the final kinetic energy to the i10wr j-aft 2w s vp(ojy)s)ta(nitial 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 t-sd7q:*h+yv avvjc ;a speed of 5 m/s. vhc* :s7t+vdv;j q- ayIf 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 2j f(qmeg7+jzcs-8 qz8bur:,r.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s.7br s+(z8,q cj:jemr8z-gq fu Both objects encounter 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 in a panic, and skid a q j+d tqt9s*( 8xzdrh5certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skiddesqh*t( z89t+xj dd5qrd, 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 S-*t1 gi;byj.y- pjxlrun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic energy?byyt.-rpilj1 xg;j* -

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 princix- gwrz anj,/3ple.

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 t* 8e2zwyzhxgex..f3;dr6 s.qpj hv /lo have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. A second objeilfo6rvzy5/pwqp( 6 9ct with four times the mass of the first if released from the same heig i/5v966q(fp rpl zywoht. 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 sprink/.empfae7/ vg causes it to stretch 5.0 cm. If anotherevpm.fak/ /e7 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 a systesf.yemat u7 noey x47z8 r;g+5m

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 potenxtuotllg6g( ;.z29 nktial energy gx; ktl(nzg2 o6 9.tulU.

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. y6an6egii0 cpd.82hg 5 rqpjll.

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 ve (ruot4ckm 7zm.9q ju4ry heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a g.o( 4k 4tmjcq7muz 9urreater 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 5 l/xulobh jol94f/g( $m_{1}$ 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 conser swscgrfz1do x4wld( 2 .sl1l x-20z,mvation of mechanical energy for conservative forceslzm- .4( 2f1w,ol1s gz2 xd0ss rwcdlx.

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 build*y9t . kqi8js:,lcdklt./ n7e fk7ousing, 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 potential energy (U) at the top of8k,t:kostkcn.7l* 9fldqe7 .ysiu j/ 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 *y,quq4yj a /p, qd9flnot ignore air resistan4l*/ ,y ,dqpju9fqqayce. How much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitatg jgf7i2r ..ueional potential energy. Do not ignore air27eijrg.. gu f resistance. How much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of con.(2: o 8sszpx0bo/jb wdbp ut/servation 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 ist ictc3 w-70l6q3 j.xh0hjjke

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 -; tygw f i.uts*abbk5b7r;w 1expressed 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 igj/(eeu9idk ux*7 h 5 qpf y4-esx6co2s not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 timesz (w(rq*p6gsd the work in one-third the time. To do so, your power output must have beez(rqd ( s6*gpwn

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 4 apug.a; li9wat a constant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If the o5 s s2i;h9onbbj :vp.tbject weighs 90 N, how much work was done b2 .ohstsijb95n; pv: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 airg ) ho0x)5my0 ztqxrl6l7l2o c a distance of 1.0 m, at a constant velocity of 0.50 m/s. What ig76lzy))lml2 hoxto5q0 c 0rxs the 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 is pulled upward with a constant force of 5500 N v x93r8ukr( d *cz(xhq0j qf/jfor a distance of 50.0 m. What isqr8k 3qr *fcj(zxvd/hjux0 (9 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 withie1znrcr 0b /b6mxji0 uj .//o m0ggt: a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of tbj mo x cgn/0:mg.buerz0jr0 t/6i /i1he elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a distauh +ls;.j u/mmnce of 50.0 m. What is the ne;hs.juml /u m+t work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up along a 3uke :v u+zjv 85l,mmg$37^{\circ}$ 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 sl63gp5f-ubg bqu7t *bi ides 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 on an icy surface (assum po2eyq 4-2u on-5xpbze no friction), with a force of 6u 2opz--n2 byq45xpeo0.0 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 tg+hl1:ttz on -he force. The graph in Fig. 6-1 shows the forct og-lzt+h1n :e 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 fka-u)* j16vdx;cr ycrue 12t oorce. The graph in Fig. 6-1 shows the force versus ;j6 rdc2vue1xr kcaot1-u y )*the object's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in theh x68jphu +/ckqc 1w(w direction of the force. The graph in Fig. 6-1 shows the force versus the object's position.hqx68(p c/k +whw1j uc 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 yumvg0i4;x i2tua5 8athe 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 movi axu5t2v8gu;a i0 m4yes 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 appli jmjkfu 2k3e75ed to move a 55-kg cart (initially at rest) across a 10 m leve jm3jf7k2e ku5l 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-rb(;vi) umk,,t*r9 qi0 vwtyomez/m move a 55-kg cart (initially at rest) across a 10 m level surf /k byzwi,)- 9*mmottq; mrvv0ue,i(race. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. q3nd-s,9iwgq-nm5 sf How much work is required to stsw fg93-5msqq n,di-nop the 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 mlrn(dw6u w1zlva-d7 y/p4j (qu+,ilxoving at 25 m/s, what distance is required to stop a car moving at 50 m/s ra l(pqjx,74 d1yw w+6unz(l/liu d-vunder 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 propel/z+q3urrud,2m z vx0 ks a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. Withu 2q z+ /drkzxm3,r0uv what 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 horizontal y4(hl6l mll6ycomponent 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 rest, and moves 2.0 m horizontally6 ll6 hy(ly4lm 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 ha cu- wcgh 7/z) ozgrx5 bj;s,tu4:x9ncy with a velocity of 60 m/s. It penetrates a dept;59n xxggtchz u)ccs7woz 4-rb ,:u/jh 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 n11syf am6 dz3from a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational potential energyznm3 afd1 1ys6?

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 s4p*exmx):2 4nqovz vlane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much 4m*e:xosxvq)z vpn2 4work 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 sk .gso zys4pm; 4)rb-qpring, causes the spring to stretch 2.0 cm. What is the spb4p-m. s;qy g4r)skzoring 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 bya0v2 b r*q;vcfai(i 0n a spring constant of 60 N/m. How much potential energy does it store, when stretchb0far; a( *icivn q2v0ed 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 uncompresynlc ws7m6 3v:sed spring with a spring7m y:w3vcnl6s constant 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 t-4x fhzgxc2ukc kjte cu le8 no+73w7l,r k7;/o stretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Aslch o,e77c-nj gwr+f7k/l k3z 4xcx2uk e8u;tsume 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 constany /nu-vargcr5m4- qd3t of 15 N/m is initially compressed by 3.0 cm. How much r5 - gv4-m ny/aqr3dcuwork is required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from thui9zs*ceeq)* e top of a 50-m high slope. What is the speed of the slier on reaching the bottom of the slope? (Neglect fr)9qusee*zc * iiction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial spjpay pe 79wmk-a6zxk *q:r8 m i7f.m:heed of 4.0 m/s. Neglecting friction, how fast will she be moving after mj9q 7m-hmkxayp6zwrep.i 8: k:a*f7dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bot j*hp4/w wcvf;tom, it has a speed of 9. *jpw vwf4hc;/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 iz6r3awq o3qr 2rw rc34t is 0.70 m above the floor, its potential energy exactly equals its kinetic 23zocwar4rr 3q6wq3 renergy. 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 fg8)tf*pho05znwsrp 3 rom ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy iftg 85 pphn)zwr03*sos 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. At s93--p tl 7hu6f e6l d rnaxty:bw8ov+the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch pt6a +o96tr3e 8--lv:y nldwp7fb sx uhoint, 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 stare3:z mv;b :z tnr,y7quw f7qrk8+-aoots from rest at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller co ,et :+ruon3zqb-7 a8mz :qofkv;7w yraster 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 sp n7adpb-z a rg ,tq95w-caiukba3:) s)eed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will bza3d-i,9c p:qat5) rks7b- wagu an) 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 the bz 8ldigz b11q0ottom of a dip with a speed ofdz8blq10gi z1 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ballknkd(-:u4g k:h(pe 2 p8t nbh*w 1rptk at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and ro*e6w;dwn * vz x)ro-released from rest. What will be its speed at the bov o*wnr;6z*e- x )dwrottom 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 - j 4zmc:ekyb1v0i x*u25 m/s hits an initially uncompressed horizontal spring with spring cons4- cmi :x* b1kezvu0yjtant 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 2000 kg car to 5g8 n3cz.dw tv)n0 nc.v:fbzp stop for a red light. Wvfz8wd0vn n 3 cnbg.c:.)zpt 5hat work is done by the friction force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.xeew9e-/bdvaes +3k*r rtsz )e1a qkd* 0g ;5r0-kg object and a horizontal surface is 50.0 N. If t/kssq0de* ;rrex * 5+gk1web-ae e3dzv)r9athe 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 a rough, level surface. It has 24 o,dgy4 9op*z kJ of kinetic energy. The friction force on it is a constant 0.50 N. How o yp*z4k9,godfar 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 to a 2.0-kg mass on a level surface. w : pw z5:e(*ktlkg+bqThe coefficient t+ zwk:lkg:*qwe( b5pof 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 tr jv481.w 4c)e/yhlc (,mo.g skrguwp he work done by friction4c)em,lc(p8guvrr. 1.s4 oww / gyh jk 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 plane. The plane is 4.0 m long u0f u30i :,qnwuhud0 uand rises 2.0 m. It requires 3200 J of work to get the bu,u:d0w3 u0 hiu0un fqox 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 plane inclin r6s .umg;(ts gb3hh+ced at 20e above horizontal. Tc g mg3(6+b.st rhu;hshe 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 dropp jada;w82jpcg )b0,f ced from a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it asb;c0jg8wj 2,da) pcaf 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 i0z2t+dqfmo)6c 0 /0 mrguzce using energy when he runs up a flight of stairs 10.0 6 zqfmegcmzt2udcor+ /0 i00)-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 mtl 2+khk62 s p1+ufrvzgbx/x2/s. What power must be deliveredrs2k fl/kght2vpx z21 +x6b+u 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 en7ylmmsjc .: 3qergy are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp =y cs3 q7m:.mjl 746 W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. How muarj2e/d1* : 7 ccgciikch force does her foot push with when she is travelic7edgj2crca 1* /ik: ing 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 average id69xep -1ni ax9 bgxr d7sf).power delive)gnxi6 ax1 rxf e.-p9bidd79sred by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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