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

1#

What is the correct unit of work expressed )ub;.0n) q i- rw 1u(ykedjnpxin 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 no motion6g /fbao5h1 ehbk4v)cj1 0rxu 1w2 l9lml:y wx?

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 statio1b/fmwowe9 . hnary brick wall, the amount of work you 1he bf9oww.m /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 n t2au4otahi -:(wo,z.0 m vertically and is being held there. How much work is being done in holding the box in this posihw2,o(: a t4o-n atizution?

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 horf)n79us9ja i kizontally forward at a constant velocity carrying a 10-N obs 9j)anki9uf 7ject, 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 r k2i6++ru l s4 clxt qir8vox.n*svx8*eturned to its original position. If the total weight is 30 N, how much work was do ixi6*k+xtl8 u lx2qcvs.*8ovr+sn4 r ne?

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 work1 4mi1 vv ,oz tth;d9ldms/jo3 on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign of t.rgux- jh- 0s1g43c stq p+mxthe work done by gravity while the ball goes up with the sign . hs-cs1xq+ rxj3mt0 ptgug -4of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) graph, represents-zg-zc7sl*viz+51cv ,m a dtl5*zvz-, -vdc i7st+m azlg 1lc

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 thkhroe-a 4,zj **vsu l0e work done by thla* es0rvh -ko4,u*jze force F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

D. the product of the maximum force times the maximum x

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the 1g gr/ gks8l(bqzn ck4g/5x.d o+j )tsobject'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 obj9:)x t9etay9u*qz ryr ect'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 kinetic ysgfg-kw bc7+ep*/o. 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 muchulxxivh39 03 cd17w tx as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy c7lwv i c39d u0t1hxx3xompared 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, and x7 u9b qfx;cxza1u:a:car J has half the mass of car K. The k :ab ux9qu7;fx 1xac:zinetic 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 bounce3jywu)*e s+k xs back with half of its original speed. What is the ratiekx )uwsy +*j3o of the final kinetic energy to the initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and no2vbr0r6 e2o8ts g1q a pebble is moving at a speed of 5 m/s. If both objects have the sasvor1 620oqen r 8gbt2me kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kghox2ilb8 d-3 e*upk 2d mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travel k2de8u-lbo2p 3idhx *s 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 cerle:h0lz5y. .,u9 bs:cvrinob c-mq 2itain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car h5 .i9 zlq-c:c:h lysmrbo,.inv2e0ubave skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in db wvhr .cd2(9an elliptical orbit. Neglecting any friction effects, what happens to the planhd2vcrw.9 b(d et'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 principlqpdod:r k8a4 :e.

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 negative pod q6tj.o ;pyh;tential 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 hei (8ftbx1iyk/nk*9za(wp)cel i,t w2pght h above the ground. A second object with four times the mass of the first if released from the same height. The pote kl* ixtw,z ae (c9it12npk8)pyb/f( wntial energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring u(y3n5mq.bfpc + ws0ycauses it to stretch 5.0 cm. If another 0.200-kg mass is added to th05myy.c (u ns+pfqb3 we 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 enexfdwc1z(pdt:(hn+x/:rr xb( rgy 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. Compare its kinetic energy K, to its potential en( 1 rttnw(atjqv8u:o1erg tqj1t:novwt r(8(u a1y U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a ca(;.xldfi bru1+ spm; jr driving 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 andqv)sx2 1c2q exe3b7n u a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises tos12b3cex 2q7xevu)nq 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 8+srnguu9wg ;jf)a( s d.wh3 e$m_{1}$ 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 conservahg )y*l 5y;-z grp (jhpmka;og27e p9otion of mechanical energy for conservative forcespzy 2om7e;;g lj 5)9hhg aorp-*y(gpk.

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, throhfy2, .s6+6 6( qdadp qpe)hoh-mtkd dugh the air (air friction is present), to the ground below. How does the kinetic energy (K) ju qydt6 hpd+h.(s pf2-dmka, e6d o)6qhst 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 gafk5alsr;mfe(p7r. kcikm8o(a72 t- nins 30 J of kinetic energy. Do not ignore air resistance k rcfsa8e7p-.n2iok5m(la tr( ;f7k m. 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 (jmcp 53 y0mhgloses 30 J of gravitational potential energy. Do not ignore air resishgj3cm m (0y5ptance. 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 conservationc-3jp:u jpd8syvy 1xxig4m0 n0--zgl 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 is ,ysela6w5is7

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 express 4s9ie5tv:2+toag pzs st*n2ced 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+dw.gcsh. 6vx wkb.l 8sk 6dm( 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, yqwq9 ,u d5fr:sou did 3 times the work in one-third the time. To do so, your po9qwsf: ,u5qrdwer output must have been

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant7t .uodlkn0(jr;8 7c2 ds+fi0 ji fhbg 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 mn h 2q 92u r g)xe)dm01osndsi3yoog yv/28w+there. If the object weighs 90 N, how much work was done in lift+v s)hom2qg0yxm2dgro o 8 d)ie23nw9ny u1/sing 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 uz0 czsh.6i h /7bomkkh7f;kj 2p in the air a distance of 1.0 m, at a constant veloc /0h 6ob kzhhiz772;.kcfmsjk 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 consl3/rwb + qw9sbtant force of 5500 N for a distance of 50.0 m. What is twb9r3l/bqw s +he 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 with a constant f2v iqy+k2js m5orce of 5500 N for a distance of 50.0 m. What is the wo mq5y+v 2kjsi2rk 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 distancbbe yuce.t-2*e of 50.0tb-c2y be *u.e m. What is the net 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 a voqh-c5mfh - ibk5 x.6/jws9f1hd on4long 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 slku y)yl- m2meg364k l1rzx l8bides 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 x*ir1nu7mtu,kufy7. icy surface (assume no friction), with a force of 60.0 N at u1.kiyftru ,x77 n*uman 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 1lj0y3skoak ub3g6yzo 8ze 6. cfu+0wforce. The graph in Fig. 6-1 shows f0ybuz3o+ 0es 3.akuzy o jl186w6gkc the force versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. y3h - u0y c3um)i bexo.b; n-jm3+nxzzThe graph in Fig. 6-1 shows the force nzm-3jiob n)3 emxcxu30h;+ - buy. zyversus 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 the direction of the force. The graph in F n+xzwjcw0r+x4.l .r:v jw* s c7na3mjig. 6-1 shows the foj+jw7vl 3rm. jnsw*.+x :aw4 0cn xzcrrce 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 objeevx- m 6u3po+m(dui djpf)e -1ct in the direction of the force. The graph in Fig. 6-1 shows the force versus the ob 61updu3imodee + -j-v) xfmp(ject's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applijzuz7 8b1o;sfed to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final kineticfu87s j;bzzo1 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 v4b:6npx7hnzcart (initially at rest) across a 10 m l z4p:nbv7nh x6evel surface. 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 witz 1g n,(ahle3uh a speed of 5.0 m/s. How much work is required to stop3hu1e,g n(z al 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 moving at 25 m/s, what h0 l a2kne 3ulegf)mo5+gc4,xdistance is required to stop a car u) meoel2fla+k n,3gxc5gh40moving 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. Itgmw e/4h(cl8nov 5soike2n:2 is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dar5o8n24omknh scwe2/l i(v: get 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 component of 80 N and a verticay.w/ afm 82jeql component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and movem82j ey wq.a/fs 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 i qa8 -diy3dt am6d(x xgx2d99ks shot horizontally into a bale of hay, striking the hay with a velo9d9a3y6xtd d8mqikx2dag x-(city of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a flo8c2h.gq*e: 6jooturv:v y 4loor to a height of 13.0 m above the floor. What is the change in gravitational pooe guo.j *:yv6lqt 482cvho:rtential 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 ujixu3c2v*o ki+q fh7*v2i tj ,rjy;n6p an inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frifo jvyu7 *ir6* iq2+kjh2xjncv;t3 ,ictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a -n7 dz si:btj7spring, causes the spring to stretch 2.0 cm. What is the springz77i- b:jn tsd 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 3 1kct- wukb(/jl;hg/:ie qwsN/m. How much potential ene(-s1cg i3 ;w:/ktwu/q kelbj hrgy does it store, when stretched by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed springx.se9m6hb y xg j 6f45zvhm*(q0pq z-q with a spring constz5qf4pshe*hxmzv m9-x(q66j0qyb g.ant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N/trc;a :;ptz f*7.v 0 xyphr27zxn:mytm from x = 0.20 my.7 t0;*7v2t p mc yxrfh:zr:ntza ;px to 0.25 m? (Assume the unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N o g0ckr 2j2giy;r0ofkys- ,r-/m is initially compressed by 3.0 cm. How mrkg- goy0k-f2c r, 0oi;j yr2such work 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 fromyo3g 5jdnpaw-a7k r7( the top of a 50-m high slope. What is the speed of the skier on reaching the ad3jn( a7ry-57okwgp 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 hill with an initi);fn wihuld6v rz4:7, 5ov cdgal speed of 4.0 m/s. Neglecting ) fnc,z:4r w;56dogvi7d ul vhfriction, 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 fri ,m:x.obn3t muctionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical height of thnmb., mto:u3x e plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m above the floor, its pow7cgj5c;h,x(hxa4a; o9u,,g xkf enh ank z4 ,tential energy exactly equals its kinetic energy. How fast is it ,x,xa5n h9ua;j,awx4(ec , gk4 z7 ock ;hhgnfmoving?

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 fr:a h2anm),m7tm zsc 8iom ground level with a kinetic energ c8sm:mah2i a7t,)mn zy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetitf87 vx3b6fq9x,zpms c energy of 220 J. At the highest point in its trajec6zmbfv7t x 8xp,qf9s3tory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the op7.wn 1k00rrv8 ,( nmszk vuxsztm00 bottom of a dip (See Fig. 6-2). Neglect fr1w8 orszu.n700 kzpmvm0rkt n0sv,(xiction, 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 speed of 5.0 m/s at a point 45 m above the bd8bo4 br/wf 9mn mt613wl 5vnwottom of a dip (See Fig. 6-2). Neglect fb5nf4b8d l o9t1nw 3w/r6mmwvriction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip w st0.qjgzyi5.ja0 r 1mith a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of themz0t0 g.1 .5ysajrqji 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 spj)+4in t-ri6z7dyv ko eed of the ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2-kg pendulum of length 50 cm is puiey+wyazmp v0x +z/7+ lled 0.16 m away from the vertical axis and 7+zx0 y+ imp+az/eyvwreleased from rest. What will be its speed at the bottom of its swing?

A. 0.2154 m/s

B. 0.574 m/s

C. 0.861 m/s

D. 0.718 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 uncompres .toz 3j xp45(pgjf: mczr/0pxsed horizontal spring with spring constan(xj5jz/m.p x 4cp30z ftpro:gt 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 stop for a red li(zhk9 um ib/u1ght. What work is done by the friction force ag b i9h/1uzmu(kainst the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horiz 4b)ang5sq*oi ontal surface is 50.0 N. If the initi*gqoin)4 5ba sal 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 kinetic oqgoys3hxmbf0 :mg6 ,i(*s-po+ uof *energy. The friction force on it is a consto(0 f:3* qxfoh*g6- uigomy mpss+,obant 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 horizont;*tyh:r wx 2cpr g08:f p3jtgc+(nhm aally 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 the mass is moved a distance of 10 m, what *(+t:hj 8grw :rathmf 0yp;c23cpg nx 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. s6fche zv,sx)rt qo+sy m2-0, If the work done by frictio hrz6sc+otx0-ysqs )e, v2m, fn 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 is 4.0 .sf rk0c -r7xt2y f3aqm long and rises 2.0 m. It requires 3200 J of work tory ra3kff2 txc07q-s . 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 releasef9 8ze* ( z,*chxftueqd from rest at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane ez (ut,h*8c qfxe9z*fis 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 of 10.0 m, and striku/x;vy* b bydrz0e 8s4es the ground with a velocity of 7.00 m/s. What average force of air friction acts on it as it fal0 br*;vyz/ s4eyux8b dls?

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 flight of stairs 10)tx/v,ido+x+e9 f qeg.0-m,gxtif e+oxq 9v +ed)/ 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 witho h/y 6i2dqsfua )9.pl a constant velocity of 5.0 m/s. What power must be.l2is 9/qpoh6 )adyu f 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 motor that runs for 1.0 hr? (1 h z,)yvwdl qo7/cmka( (p = 746 W(mq wky,lv/(dca7)oz )

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 for6ii ;z kkh*c8fce does her foot push with when she is traveling at 8.8zfci i*hk6 k;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 averagw as8zriwgj 04c1y4y *e power delivered by the engine? (1 hp = 7*4wgzcy81 i0w r sja4y46 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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