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

1#

What is the correct unit of work expressed in SI units?ncjzpf 74+ 3up31v 9p ;zud,iudfs. bs

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 d/1j;6 gctja(dl agn(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 stationa g2skfwlbb )p36g 7ybw:9z1sxry brick wall, the amount of work you dx bg fgwps:7b z19lys2b6w)3ko

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 ang7:e u1k gt9u/- l+gridyocv- d is being held there. How much work is being done igut 7-1:+g9k ul/iv-eyg cdro n holding the box in this position?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizo2f:v gs1t* rihbqao9-ntally forward at a constant velocity carrying a 10-N ob 9:* rv2bfa ighqsot1-ject, 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 retqe1,pzwg c0nbs15tcwe 1.0 vlurned to its original position. If the total weight is 30 N, how much wor5w. ,ts1vcwpe1 qgz0 l nc10ebk 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 o8 8rk*mycb9j lj (q,clbject 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 stra6gx.y * bn8r:ia(dp nzq(y7 eoight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work d(ibxgy6:q .e po(y7nr*8nazd one 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, rh+w0n1eibtq z27k* fn;bw 0 dwepresentseb01hf+*kit ;7qw nbwd nw20z

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the )/u zgfr 4ib+rmqrk3-f 2tzv*work done by the forcfuv+rbi*q )z4tfkz2 3r/ r-mg 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, nrl ny9vw-/n0xhq 9idxi+l ;iq - wz+4then 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 on an object is negative, then the object's kinetic energyvbw/t wv67sp7

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 5ck 4:jbbk(q yuql6rw5o 8it4an 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 as much as a car, and is moving at twice the sh(-6-v6 l isgt0qx-qa1j2ex qwxl 0f ipeed of the car. Which statement is true about the truck's kinetic energy compa0e6qfa1 i-0xhiq l q(sjv 6l2txg-w-xred to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, anb*u 1j .hhahz) 0oai-bd car J has half the mass of car K. The kinetic energy of car J, compared to bi a-.z0 huoj1hbha *)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 h nr)o0 o1:x nmpe8jw+speed. What is the ratio of the final kinetic energy to the inino0p1 wr8)n +x:meojhtial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed of 5 mw2f h f,y(1jom1xv b9b/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass jfv1ow1m9 b(yf,2bxh?

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 spegdou)bk ; 4v9fed 4.0 m/s. Both objects enco) f4dkuob9g;vunter 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, anwo-n7p n+z6ttd skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have sk t tnozn-67pw+idded, 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 orbithu0 d:hhjh u,7s the Sun in an elliptical orbit. Neglecting any friction efuhj07 ,hdhuh: fects, what happens 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 prin,t*6hr+fy qev 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 sykk gn 5yf+,h0svqhe4,hpu gkh(u)5q,stem to have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the gvc(s r8/ux8h yunzu;oy7 b:7rround. A second object with four times the mass of th/ usub;7y 8(vrn:7y x8hrc uoze first if released from 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 tdnr h++fj18v yhe end of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential ene fydhv +8+rn1jrgy 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 e 3mom b v8/m1u7inyu+energy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a treep*t,i6nl 7px ahf3lkc 3wu92w. Compare its kinetic energy K, to its potential energy f 63w72kw,3xpt9lci* pahl u nU.

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 v9(0q,ixa ger up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are sliding with eqg y y3w rk1c4aurg,v:;ual speeds along a level frictionless sur4wc ;a,gyr1:ug3 rvyk face. 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 3w dq9(. jczs8,xj6a:r fjwqh$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical energjvto9qj m7.1 0o x*m hh5lu; 6wewfcm)y for conservative forcesw 9wju;0hm v 61ocm.ehtfx l)7*jmo5q.

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 buij 6l c:u/g0t7d) elufxlding, through the air (air friction is present), dxc 6f/lu7jg teu):l0 to 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 and gains 30 J of kinetic energy. D wuh aud:ejq(b;6712bi1cy mpo not ignore air resistance. How m ybdcj i2(uub: 7m1qh;awp 6e1uch 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, p1kd7s0m2 e/orpnbm cs:)t o J of gravitational potential energy. Do nos7pks1 :rtn/b, o mo)c0pmd2et ignore air 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 conservation qe8w*ge a4l 433*c0tg3q ;m xqyncdncof 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 is6:z 2:h gyugsk)y8j hj

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 uni7kqs2g uj9k7n 6oc l:pts?

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 poweb:22,w x2 t; 2turmj +rgwq-hj2dnopq r?

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, knh2+ rz9uxhy :3k we3you did 3 times the work in one-third the time. To do so, your power output must have beh9yh3z3:rew 2uk kx n+en

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 aclb,4ask )ypf;0b d8yoceleration, 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. qdp+r p 5g3c*+0khg oqIf the object weighs 90 N, how much work was done in lifting it?h 30g*+g qrqkpc5 +pdo

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 constant57oyqim.w;zf:n vzp,pd/ f lnb2 5 b3j veloc7 fwpjo d3z.qi/ ;zvlnb nfp y5m25b:,ity of 0.50 m/s. What is 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 0hl hvsl7srp) z;w4u-constant force of 5500 N for a distance of 50.0 m. What is the work d-l z4l7p s) v0hr;uhswone 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 upware 4 q.l, pk nt8uj6tz hz:oj;gjze++5jd with a constant force of 5500 N for a distance of 50.5n; kp:4l,8ujoqzjte +. gj6eth+zjz0 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 for a distancxf8fl g+92g3tv yi;uhe of 50.0 m. What is the net work 8hf+f yggu9; xvi 32tldone 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 ba4e9vsmav7 zm8tt1vit 5ac2 j e( *c,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,nsm6tdlsq3-0i pmz (es 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 icyikb 2w1bikk x 4k3-e-x surface (assume no friction), wi1ekk b 3xibk-2-wxik4th 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 Figt1/a 5u3i)l-ka iftyg. 6-1 shows the force versus the object's position. Find the work done when the obja u)-lt5 3ftk/ai1g iyect 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 directio v v+q8de d6;vmp.mndf +7qyk3n of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the worm3v md.n8pvkq+ +7d vdey6f;qk done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. w 7,lrqhod,+q m mwgfb-e -k-4 The graph in Fig. 6-1 shows r be 4g--lw-wd,kom,m qq+f 7hthe force versus the 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 th,;1qcs kpv jm3zur*/ xc5nho :e 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 opxj cchsv15 ,u/:;m3r zkq*n 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 (initially at restu13p vi vtx8:t) across a 10 m level surfacpit u3v18tv :xe. 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 (i4hhkws 7k p(:wnitially at rest) across a 10 m level surface. What is the4ps w hkk(:h7w 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 6s-tp8,mi- 1t6nrv gtx8 xi mom/s. How much work is required to stop pvs 1tgt x8,x6oin-m6m 8-ti rthe mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, ms0 9ve.k+gpemqng3 7 what distance is required to stop +mk3 qgs g. 9evp0e7nma car moving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propel ef-(sl+4wl/ j vkbt kee ukoc/1,4.wks a 10-g dart. 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, assumis.koe+4j4ll-ck,kt(kfw/ e/uwv1 b e ng 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 zm2jbxh7q ) ws4j ,um2component 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 horizh mq2bsjwu7x )jz2 4,montally 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 bal0 q 8lipef6j,ye of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the averageyl i8e0fq,pj6 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.gxk86 df;cfp7 00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitatio6;k8dc 7xgffp nal 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 acm3.rs4wjaz +54w hddn inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much wr4 hsm4+d .caw5 jzw3dork 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 ontogjbcwht ;; j+cuu/ i(8rc u6cdkf:.p- a spring, causes the spring to stretch 2.0 cm. What is the springkfc.;j+- p8u/ ( thc:jr6g wbu;dui cc constant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a s :3 s:ecbl n6sljof4k79ada hj .5:klypring constant of 60 N/m. How much potential energy does it store, when stre4s5n:ah:yc kkos jll d6 9 elbf.j:a73tched 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 init )z y2,u+pkivlially uncompressed spring with a spring constant of 25 +uk)ipy 2,zvl N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constash6 mljuvon 7 p e*y6c+hbo m4-).0grqnt 40 N/m from x = 0.20 m to 0.25 m? (Assume t6uh.m 6ol mcqr*4h e07+no s) v-bypgjhe unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3.0 cm. H ;-q)ev*4qna yuzi7zg -cxksa/x/3x oow much work is required to compress the spring an additionex74/*xniqok zvq gs/y3cx-z ;)aua- al 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 the top of a 50-m high slope. What is the sor v+nqgkc ,f8(:v ge1peed of the skier on reaching the bottom of the slope? (neglect fk,ef:(qrgo vgn8+c v1 riction)

A. 22 m/s

B. 31 m/s

C. 38 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the tojjya0rvh+g)upp+tl 1u-x 6. r p of a hill with an initial speed of 4.0 m/s. Nel jyv.0xu1pur6- rjp+ ga +ht)glecting friction, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. ub * -.i 7tdf92dtpf1wjc0n ef At the bottom, it has a spetdf.tu90pnw j2 -fe*id1b7 c fed 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 flxte u y(.csyj95lp5bj65v )rsa3m fg9oor, its potentup yb 9jes5(l5vj 6yf.) t 9sgc5amrx3ial energy exactly 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 fro)srsc 5bo: y3mm ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height soy m3b ):rcs5does 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/jr3rh .z dvm ixoesh+f8f48mc.x9 6g 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launco sh+6x4 vrd /988mm.gicffj 3 hze.rxh point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m abovec1-- i 3i.n:tthiixeq23j gzt the bottom of a dip (Seejiecqt -23:n3i. hi-g i1ztxt Fig. 6-2). Neglect 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. 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 spe6(g jgish f2q+ ,/adoy6 v5h0 kvfv4exed of 5.0 m/s 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 coaster at the top of tho54+y i gf6,xdv e ag/vskhh6 j(2qvf0e next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom h 3p7c*/tth4rn te(w:q+yd bgof a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what wi*hrt wgn/hd:et(b7c4 tpyq+ 3 ll be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottomjwf va-/o wpd871.rmp 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 p v+jk aa1-*lf9cnk8d vulled 0.13 m away from the vertical axis and released from rest. What will be its speed at the bottom of its sak9j-kdf *n8+vav1 cl wing?

A. 0.1742 m/s

B. 0.464 m/s

C. 0.697 m/s

D. 0.581 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 a j.n;f)+ gt(qlere,zdt 25 m/s hits an initially uncompressed horizontal spring wilfdrq(e n, g.t+z)j ;eth spring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slk2l7 md;7k ix/)qmm i(l4df umows down her 2000 kg car to stop for a red light. What work is done by tkiu(l)ixl2m; mq4 dm7dmkf/7he 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 b-;/ q x,zov:;xpxtez/-hko dc etween a 60.0-kg object and a horizontal surface is 50.0 N. If the initi ;z:z; qv/ -x/-ocxo,hedtkx pal 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 J of kin eci/,4j utfyc2v-y7z5yyau 7 etic energy. The fri7c42eu /vfu cy7tyy5az j,-yiction force on it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontallyy- 3 .c mtb qjorxc:yhjwhze5f ,a0*r9wt(.7d to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If th5,h. 9tce0rojz :w(fyc-xthq bd*a. j7 rw3my e 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 res;vaxmf5+:28vgukwd m 9 i l1hyt from the top of a 50-m high slope. If the work done by frictiavfk ud9 8:givxh;my m2w 5l+1on is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane*8thr0o: i ou3 whjq7d is 4.0 m long and rises 2.0 m. It reqho80 q3 *tr:hwodju7iuires 3200 J of work 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 releasediekrmhf/c tm0u 9s7)4 from rest at the top of a plane inclined at 20e above horizontal. The coefficr 9mumiekh74f s0/t)cient 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 o z)vmcs/a7 *xif 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it as it fs zm*vc) /axi7alls?

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 upzv p;vcyxk kv)z0k, 2- a flight of stairs 10.0-m high, i zxkvk -0,) 2vkcyv;pzn
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 velo+mkvp5tw -f9 xx rnt2:city of 5.0 m/s. What power must :txn 9m5k+r wpf x-2tvbe 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 e, qbytfnhfd 6oij, 2/6nergy are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp2, ftjfob6 6q/h,nyid = 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 ridiq f4 m))ixg wer4 ebzqw;d+)3cng. How much force does her foot push with when she is traveling at 8.)qz+dmwwb )i qg4);xee3 r fc40 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 0g+ t-,)xn(vy n:csrhg to 25 m/s in 7.0 s. What is the average power delivered by the engvt)yg,xc hng:s r(+ n-ine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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