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

1#

What is the correct unit of work expressed in Sz7fkf0lj ;zm5kuvi.(1siq1 h I 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 systdt3k1 +m ej yo33v1bnxem if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the amount of wor dj*-o a1e1vwzk youzj1a-e* v1 owd do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held there iq55wj9 ;8yvzugaj:zyh- o7w. How much work is being done in holding tj5ywi;-w a zyv5jzh:q 897og uhe box in this position?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constant velocity carrying a 10-97;e nz(1h:0-bp rcnull hgcfN object, the amount of workepr g hcc ;9u(7lf:-hb0nnl1 z 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 g),1 4fshm xl8uuv5rdreturned to its original position. If the total wx 8dr,huu sf5 g4vlm)1eight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work o3p dk+1o exhfd(( wnjjt5 h;v *j,4nytn 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.hc;y z3, 4 mzpf4akm0z Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it mm 0khyz;c, a4zpf43zgoes 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) ,1nvjljs)j xbv: vx2, graph, representsjxvn:xj,sb,1j)v l v2

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 versllg7uu;an6r p)(fr f2us position (F vs. x), what represents the work done by the force upfu7r(26fa nl gl;)rF?

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 th(euc7 2 xct/voe 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:zm/0 y g+f+)dv y4r wrkowrq0 is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the object's k(r s:uiphd/ lmcy*fin .m)f lf;6;,m ainetic 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 qk ppqrz0ls-2;iiu*( -vn6b dcar, and is moving at twice the speed of the car. Which statement is true about the tr-k2qn;b0 i-zq riu ( ds6vlp*puck'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 fast as car K, and car J has half the mass of car uox4(s0/)upq2ym04 avnf ablK. The kinetic energy of car J, compared to y 4xf nq00bl2)o aps/uvma (u4car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speed.ez7, /s +4gi f+g, (rxr/spuoyyktu *i What is the ratio of the final kinetic energy to the initial kinetic en 4,uss*,/z 7ieryk+ gyo+x/p fgur( itergy?

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 spee((, 4hllwl0-v26bhwf ei o ergq8/jlhd of 3 m/s and a pebble is moving at a speed of 5 m/s., 4blr-62oli(q(8jef/elw h vwlg0hh If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mplmn*/br --*b s, )6ax3 os ewn*lbvcxass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which obm* v wn3 x)s *lasnbrbc*ob-,e/-l6xpject travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a certain distance on +vl x.74ia62dm0j h ub(uitq ca straight, level road. If you had been traveling twice as fast, what distance would the car havedhu v+6qi tjx.mc4 a7b 2li(0u 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 .fd ag);hw st)rpp-n9orbits the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planpdrsnf twg;9h)pa.-) 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 principl-t 4okd 2*k o,atfw.eq nlnn(4tfu l5)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 mx- vm81jwg r53-hyfcs:lrq)d (q r(m;6pmvzpotential 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 rkj 5/0qzbvv308p*vw k9azp peest a height h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second object compare v0 w3b z*8pva09/vkpjq5epkzd 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 causq pg0u+uv+2h sdc3re e iez.))es it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potent zq))eidv.ep0ge+r 3 cs2 +uuhial 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 tolt+1nv)b swg 1*i7mof 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 energyovwa47e7eoqa1 o-ob)e 6pd )x K, to its potential energy6e)o)v q 7-e7 b1x4opdeow aoa U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car pq)d0 v /zj*x*e .*j;jbrr zdfdriving 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 heavyst2+03aa8 xnqj6 fsxa object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a gres3an0 8 jxsxfqa +2ta6ater 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 tl(x7wa hg y+ kp8,bhmi4r ,1p$m_{1}$ 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 m8dhef(an 9qdrfw4dr h 7,wq ,-echanical energy for conservative forces.hhqfa7d w(-,rwndfder, q 8 49

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, through the air (air frictioexd-u u(z; jszj2s(09nd5 ouzvj1 w( wn is present) (05j9u2dx1zvuj; (u w oss-jweznd(z, 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. g( 5lpchgllgmf 82/7t Do not ignore air resistance. How much gravitational potential gpl cl8 m257t(h/fg glenergy 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 lose6pr16dzyd,d lqnt)j38 fyr*js 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic,r86yy 1nl 6rtjdzddqp f3*)j 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 of en( u;gb/ 0okwck4l 0liy 4 t:crfz9qbz4ergy.

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 isu4o 3gko 0n,ake9q n;q

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-2ky qr:ub0ttsed 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 no+nc ghv /g7b,ym*ikc :t a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the time.gqwb h+s(wl40t q;)vs To do so, your power output must havhwgt0wsl4v+bq q( );s e 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 consto5r(ca0wf-odu,eg3vtjpy)w 0 y zu.)ant 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 ann3gd2vk.w d4 e) ukd(ed held there. If the object weighs 90 N, how much work was done in l4 2wend )( 3k.deukgdvifting 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 7aeis i0y f5sg(9ss 29j1 zh78rgxrmga constant veloci(8m92asx 5ii 7rg esh7sj y0rfz sgg19ty 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 conszbi n,/- a.,lq xwrd5ytant force of 5500 N for a distance of 50.0 m. What is thni -d.wl b/yazq,x, 5re 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 upwarb1// aqpk.5(v 1skmv ox /vzkxd with a constant force of 5500 N for a distance of 50.0 m. What is thepos/ (1q/ kv5 xab/xkz1 vvkm. 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 pulledg2 g/t uke6wv9 upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work done ovku e 2/gwt69gn 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.pj bas) .m0fd80 m 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 fruit slides 8.0 m down a ramp, inclinn5gq f(,fcu z.eeh q)j5m9 7wbed 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 (as;j i,d.b6 szvzsume no frictzd, zj6bv.s i;ion), with a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6-1 /.*hajj zww;pp isfwae7y w905w x i1/shows th /ayj*1a . iwxes/w5 0f9;pww7wzihpj e 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 ogcs8f)woi 6n +i+) k sogvuw0+f the force. The graph in Fig. 6-1 shows the force versus g06 ivsfno+wg+ciko) +uw)s8 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 Fig. 6-d0 fmmf2z7*dr;wvo:7m* c 7q.va nxdf1 shows the force z7d;mnwof a2 *vxv d:0 fdmf.7qr*mc7 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 the direction of the force3a5pen: bc589gdz eie. The graph in Fig. 6-1 shows the force versus the object's positn59dcz3 gi bpe:ae58e ion. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initiall2q kar/ns g-q:(+yfyiy at rest) across a 10 m level surface. What iny+ qq:2(gra kf/ys i-s 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- j u)+blpnp(w(kg cart (initially at rest) across a 10 m level surface. What is the final s)w( u jp(+blpnpeed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much work is reqs qg: v(az/bwbyr0i6/ uired to stoy/i gv6bba(0q /:zwsrp 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 4s5:om4 txe*mplxh6oa js: 7h)n x.lam/s, what distance is required to stop a car moving at 50 m/s under the same 6 m xl.:ph4no:sal57s)am4ojx *xhte 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 propelrhbzi:6 2 hlx(l i:y-p4ag 4tls a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what llgh4 ti4:6(a2b:yrzh-xplispeed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a vert *lnbo-el/t4ak3+n o/lg:whmical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along th/m l4n/+l3ook e -:an*hl btgwe 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 horiz5csvd i2ea*1hk0 j zow3i/y,zontally into a bale of hay, striking the hay with a velocity of 60 m/ 5i z2j *okze3hsya0d/ci1,vws. 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 m q(t zl3t*v2ib.asmoo ybt+ /*oved from a height of 7.00 m above a floor to a height of 13.0 m above(lqv iso3 bt/t .*2*mbatoy +z the floor. 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 an fz ,yl)rqgf)k5f 2 d.d2rw2fpd rises 2.0 m. If the plane is frictionless, how much ,rwdf5z)r)2p qfgf2d f2 kl.ywork 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 spri fcn-e)84qpqe hc 1c,nm p.q+vng to stretch 2.0 cm. What is the spring+ .nhq pf,1e)q-ecqpcv8nc4m 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 character((.p9c,/hrg; t dofvse tqi4vized by a spring constant of 60 N/m. How much potential energy does it store, when stretched ig te;v.,s/(p9cot hdv f(4qrby 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 f3z hxhu5ipxasg2bq i6 905+c initially uncompressed spring with a spring constant of 25 N/a6iz2xbpc+i59g0 h sxuh53q fm 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; ts3)q7iqkci.ie;asu8 az o+ 40 N/m from x = 0.20 m to 0.25 m? (A;cqsa8)qi+3.asz7 ; itiu o ekssume 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/m isqidm k4 +zc9is7l e,;p1p3iup initially compressed by 3.0 cm. How much work is required p smu3l1 9pz+iep4q;, c 7idkito compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. What is t*+h)df tm 3cuwhe speed of th+duc3f *whm) te slier on reaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial speed ogo67ray- v j:ef 4.0 m/s. Neglecting friction, how fast will:yjvg7e 6 rao- 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 i ufs)ony0d1b ,nclined plane. At the bottom, it has a speed of 9.80 m/s. Whatob)fu0, s d1ny 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 floo)yyiqis ) 2784/gph*jvb0p tgja8mzqr, its potential energy exactly equals its kinetic energy. How fast is it movi0 ) 7qgv)p y8jhgbia 4 jmy*8qiz/p2stng?

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 grouny.nj0u.* w,l ;khuoszd 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 hhowl. uus.jn0 kz,;*yeight does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy of 220 J. t*ng)jh u as)g4-pnx) At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its la)g-j) ap hx)sg 4nn*tuunch 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 ehgsw o816, wuabove the bottom of a dip (See Fig. 6-2). Neglect friction, whatgo6ws1euh ,w8 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 r*kf-pbno/o pv0 q; u0with a speed 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 the0;*0/ovfppku- orn bq 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 poinj nwwyz( z3 k856n,pw6mk 0ipit 30 m above the bottom of a dip with 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 the nkjmzy,w(k5ip 6pz w30i 8n6wnext 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 bottom of its swing (poin- g.) fgyk rbz/d5dk1 gfym/w-t

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from ths+ 3 gz+p*jtwue vertical axis and released pw+gzt+ jus*3 from rest. What will be its speed at the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an iniy,qlftq:rlyl 9hvt51n+ /0 futially uncompressed horizontal spring with spring constant of 9h+l/0,fy r quflqyl15:tvnt$2.0 \times 10^6 \; N/m$. 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 r k7qid.-r2)wr dljt57)b*dmp 7y o dpto stop for a red light. What work7)o rdr. d)qik w-ty2rmpjbpd77ld*5 is done by the friction force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force bed2 m t /yd/4atwn :5qg(4nb;fyyie5ghf:vu: ktween a 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of /af5qw u:4:ttyhdgy 4g y ;df5/(ienm 2:knbvthe 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 mov5 :z1vhcu.wuz.xfj p1lp5.r ning on a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constan p:1w.. 1 z.luphfj5uxvz5cr nt 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 2.0-kg masirj2rsaj; 22xs on a level surface. The coefficient of kinetic fricxs 2r;jia2r 2jtion between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50h2 aqw2j-q0xr-m high slope. If the work done b-qwa20qx r2j hy friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inw1/pw0 ockx qc+ w*zz2yk7wr 3clined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the to7pwo0z3wk/rxc k2w*c zy1+ qw p 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 of6)1*rzoeeql p a plane inclined at 20e above horizontal. The coefficient *elz6rqpo 1e)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 heig i/ybtkae /o8n720su zht of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air fricti8ks ezntiuy7/a0/ob 2 on acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-k v5mxwi.-q .caa3nf2sz; /vo udl59 lhg boy using energy when he runs up a flight of stairs 10.0-m high, i5xfsuazno iac2;dhvq5/ .llm3 -v w.9 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 object with a constant velocity of 5.0 m/8cw00 t1z-v mi bmw*sys. What power must be delivered to the object by the fo8w1m* vis0 m0 t-ybzcwrce?

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?xe6hxm kaahz wuq -dv9*h7 p14a9*w7v (1 hp - vma* xpwhe7kx9d4zv aquh*h169aw7 = 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 wgb48bn 7; c1re4 mld3tjdyl8at the rate of 500 W while riding. How much force does her foot push with when sh l143nb;ej r4lgwc 87btdm8yde 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 jmxe w (b(e.h(0 to 25 m/s in 7.0 s. What is the average power delivered by the( ((eh. xjwmbe engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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91	92	93	94	95

1	2	3	4	5	6	7	8	9	10
11	12	13	14	15	16	17	18	19	20
21	22	23	24	25	26	27	28	29	30
31	32	33	34	35	36	37	38	39	40
41	42	43	44	45	46	47	48	49	50
51	52	53	54	55	56	57	58	59	60
61	62	63	64	65	66	67	68	69	70
71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90
91	92	93	94	95