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

1#

What is the correct unit ofq99zny vetwj5tj 49h+ 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 there is gou* rtx) :cbejywt2/nzb -):u 8 xuc*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 againstrfc -,oql 6)je a stationary brick wall, the amount of work you - r)olfc6e,qjdo

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held there. How much n w zj ,y(bps*s9:2o, ecrvt2swork is being done in holding the box in this positios,*22 ero zjc ws:t,(ysb9npv n?

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 a 10- i8aw8hpeas ty,9o8 sw 0p+z8tN obo9 ite80 a,pw+hpysst8 88wa zject, 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 mj*ok; 0ss2fx k7t ( 0ux0rpkoo then returned to its original position. If the total weight is 30 N, hoo kfx0(t k;j00x o2ru7 *kspsow 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 object do work on the o2a +d h,plzqc6bject?

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 updwk,n)7gt,mgq9di zd.j4kp; . Compare the sign of the work done by gravity while the ball k m,gk;9w.j, pd74ddnztgqi)goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curver55e)e-/dias+oqjhw , on a Force versus position (F vs. x) graph, represents5w5dro) +i -a/ ejhqse

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 popt.9wr3 cgw5gh v2, qbsition (F vs. x), what represents the work done by the for5. h2 9,t pc3gqrvwwbgce 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 yrabl+xa5( v)on an object is positive, then 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 ti2a : zymitz)7he 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 ot;xxg cx1(g )hbject 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 aw71d*gib+2wsnaxyn ; s much as a car, and is moving at twice the speed of the car. Which statemyis1gb+wnx;2a d7 w*nent is true about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as/7(3o9 dmve 5pufgpve fast as car K, and car J has half the mass of car K. The kineti/3(dp 7 gfeo muv5vpe9c energy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speec(pc)p;a2f t yd. What is the ratio of the final ka(yc cp2;pf)tinetic energy to the initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebbld+1a8b,qo7uq ;dpe*vm yo z:h e is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what ib,18a7uvo d ;dhy q e:+mpo*qzs 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 w egk4h-jni .gdp* 1*2mt 7f*ldtav1dbith speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same 1dmp 7* d.k2tg4gheidf b*-lt 1*ajvn 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 im)a;os:2e y .goh6tpkn a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, utmheo)spoak;gy. :2 6nder 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 constantlcn;b8(+f d lara1i /g mass orbits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic energf8ra 1l(i /b acl;d+gny?

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 p/ ogr*hf7 l pehh0a.z-rinciple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; kx^2$ is

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have nega qtu05d6 1)6esgqu pe8qte4ca tive 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 objeczip), uu(ngh9 b s9-y1kwbv 2ct with four times the mass of the first pu,gn w1kbi ub9yz(-29sh)vc 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 the e suku-:5vn4hend of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the sprinks: uhen4- 5vug, 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 wrmgptnf*7 m,5)-p zmfxi4r *of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Cr14 6btnk0g* mesjmrp7h03kuompare its kinetic energy K, to its potential energy j0m0gu 4 m 6erkbtrnkp13h 7*sU.

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 drivin78z cliwhcpg0 ja;esag 4 .)n,g 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 verk *.y i0w+wjt6w/ dna2mit n,jy heavy object are sliding with equal speeds along a level frictionless surface. They both slide up thet*w6yi,+0 m/twj 2akd.n injw 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 p/j xh/5w;sx0(i vg2ku ibky 3$m_{1}$ 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 conservatio7,zoxu qlflxx.1/- ctn of mechanical energy for conservative forces.,u cxx7o/fzl 1xql -.t

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 onj(zz/ 6 vxe uea5v+i6f a building, through the air (air friction is present), to the ground belowz av(ui jx6+e6 e/v5nz. 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 enervb 20 pb/a-dthgy. Do not ignore air resistance. How bbv- h2p0t/admuch 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 gravitation /b s*u;u9ax vmm92tb80 awhanal potential energy. Do not ignore air resistax 9m *u ;uvt awamba/8902bshnnce. 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 conservat qf05y(kakvm5ion 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 isaxx 6qzt0jfc// (-w) (qy94fjcvdaok

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 expres.b.ve 15p/s cl9e prossed in SI units?

A. $kg m/s^2$

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

C. $kg m^{2}/s^3$

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit of po3qqmb k6).u/uwu flk.cd0r 5 cwer?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-thirdmy6h, lz9n y-i the time. To do so, your power output must have beei, -9nl6 yhmyzn

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, thxlnyfm556gkw6j /y0ne 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 : bhysa/ud;1a2.0 m and held there. If the object weighs 90 N, how much ya:1us a/ hbd;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 distance of 1.0 m, at n gw((m(ywr0ta constant velocity of 0.50 m/s. What is the work done by the weight o0(n rt((mgyw wf 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 550hz qe0z65 dl(k0 N for a distance of 50.0 h5k(l6z0q ezdm. What is the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pull 101o+cvswatd;*jkt6m s9j p-kqm2oc ed upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done cov 2q sj s1ko ktj06p*;cd 1ta9m-w+mby 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 upwl38m yhe07y yyard with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on tyy 87l3y0m eyhhe 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 jpekd/u(s1q8 up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit3 kly(u-cu+x58wd.f curn9i t slides 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 (assume no fr*xdyd :ou )fe)iction), wi*xd yd:e )of)uth 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 grapx4ttc1- h1c mnh in Fig. 6-1 shows the for1 m41ctntc- xhce 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 1cum.rtm25 usd5tyf*the force. The graph in Fig. 6-1 shows the force versus r 1t2.*cfs dumm5y5u tthe 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 the dir: z:gjo1ac pxzxf u2/2ection of the force. The graph in Fig. 6-1 shows the force versus the object's poc ao21z:xzpgj /u: xf2sition. 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 objectsym. zxbqb;2 7 in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done whenbzbx. y ;7msq2 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 mov a6j :md7y21aprae u*fe a 55-kg cart (initially at rest) across a 10 m level surface. Whataym uaj ap e2fr16d7*: 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 55q9eu-nxuy: ) o-kg cart (initially at rest) across a 10 m level surface. Wh:x9noqeu - uy)at 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 5.0g v49 4wgcam:a :bjgq,op q))x m/s. How much work is required to stop c4gagwq4j vgm)qp,:x9 :a)bothe 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, what distance i;w;yqk/)ceyk/u ;h ojs required to stop j k/ h ycq;wkuy/;o;)ea car moving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is cocked by exerting a force ow zi- 3q9mz7ql9t9 gyq l+.buof 20 N over a d3 +zl7iguwm.9tl9 -z9qy q obqistance of 5.0 cm. With 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 h3 o ( if/mr:if1( 0.0jitgwwyjiiqc6worizontal component of 80 N and a vertical component of 60 N. The force is applied to a box which rests onjt/wj(mi (w1 i:iyw0 iqc.gff3o6r0i a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g iab 1*dyni+qm*w.js6 h s shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penet+bqnyjw*d h. im* s16arates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to ;x 1y+vo)i:1c)otbd llb2gxl a height of 13.0 m above the flodxl)2 ybv o1clbi+1lo ;x):tgor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m long and rissbqt1t4 . :d5i2ywchb es 2.0 m. If the plane is frictionless, how muchdcbs 54ib:1.t 2w yqth 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 scxl(fu ,5kk zhrpe29m8 72 evxtretch 2.0 cm. What is thele 2r czu9 8kemx52kpxf v,h7( spring constant?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much p kys1mes6x h .-/vm*hpotential energy does it store, when strsy6- k1*.phxhv s/mem etched 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 rnmp eqx02tm11 equired to compress an initially uncompressed spring with a spring constant of 25 N/nx2pqmm101t em 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 constant dro:1guwbq 1g h3gu. 5djd;9j40 N/m from x = 0.20 m to 0.25 m? (Assume the unstu d;1 q.gwo :ujggdb1hd9r3 5jretched 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 3v8ntih1z. )dpankl( hc (jyyb e5ajw+v;k4- 1.0 cm. How much work is required to compress the spring an addyk;v( i(dh.+abjewya chp 1 t)nk4 z-51j8nlvitional 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 2 g,occz-dchly * cl/0 z,7zxgcm- s6lfrom rest from the top of a 50-m high slope. What is the speed of the skic-m*lg2zxcsy7,0-cd o zzc l6,/ hcgler 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 the top of a ,upg22hzg y5qhill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving af,22py g 5hzgquter 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 t(w/5v8-k wjp bhv6urfrictionless inclined plane. At the bottom, it has a speed of 9.80 m8v jwbr u/(hwpv- 56kt/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 floonnjz ji gl q30i+6t-n:wlkn5t0y(hj -r, its potential energy exactly equals its kinetic energy. How fast is it 5j+hn w y n0 (t6n-znlikgj-ti0:j3lqmoving?

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 with 3n3ux y57c0 mxofe 699jsittxa kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height d f935x oxtuyxse9 6 i0jt37cmnoes 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 ,8qzvftau *3m g cl4r)220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it u*mgtfa) q rv4,zcl83 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 sklg/ 6x+2v iopoint 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 of2 o giv6l+sx/k the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.fs;ndkt/0 3v v0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, 3n/vf td0v;skwhat will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip with a spm+7)zob2*v.v77n qe wsqf j hgeed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speeqo)vzm2s+.h7qwe7 7fn gvb* jd 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 ballwdop;m inls- (m(x)a3x gzv.; 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 0.25 m aq(eb :t1ruuw+ bu1c r:way from the vertical axis and released utr u11+(b ubrecq:w: from rest. What will be its speed at the bottom of its swing?

A. 0.344 m/s

B. 0.917 m/s

C. 1.375 m/s

D. 1.146 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed hort -25o5af mpdrizontal spring wpamor-f t55d2 ith spring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 ;.a8u so.pdhvkg car to stop for a red light. What work is done by the friction fdas8;v.p u o.horce 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-kt(ha(w + rf7 jaeo8:uh /po02/p oi3ujh,hbrqg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/sh,ro72 uouq hi: a(hteoa(jp/j f wr830b/+ph, 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 surfacey4/pl.gj .oyv . It has 24 J of kinetic energy. The frictioplgjy4/vy. . on 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 horizontally to a rv8jm*dsqq2 .md 32iu2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is t3q q2mj*8 s d.rmi2vudhe 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 the work dud8 +u9sr1x8a0 epclrone by friction ie8l019 xsc ap u8urdr+s $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is 4.gemb6:9pyf0p uem,2v 0 m long and rises 2.0 m. It requires 3200 J v0gep ,p2e u96:mymfbof 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 released from rest at the top of a plqzk-q +,iisso* i/qz)ane inclined at 20e above horizontal. The coefficient of kinetic q zozk*si- q/q+)is,ifriction 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 oq va t:x/6tl0hf 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:h a/x0vt6tq l 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 flk r1s2lld m7lu: +0p frkwq(yht -af7bp))j7might of stairs 10.0-m high, i+m pk blhfsyj autlf1(0m ) q7kr2r)w7:p7dl- n
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 objef; b +p: qnm68syntx7v ct9.khct with a constant velocity of 5.0 m/s. What powe cp7 6y+mxttq8hk . svb;n:nf9r must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp yjtprb9qsmpd4)* 32pascy 6 .motor that runs for 1.0 hr? (1 hp = 74yds49pc j)2st.pb p36ra *myq6 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 forcejjm1-e pg* 5a(q94lbno zbv0m does her foot push with when(neqz a10p5bm9j4bv-g*o ljm she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is the aver (seyb4 mdltc6 r5m)+dage power delivered by the e st(emdc+y)rm l546db ngine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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