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

1#

What is the correct unit of work expressed in e8yb; abg8xoa;p8+wb9 q1h zqSI 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 systemrzw7 tjj(wrdu 9lsu)(/: br9wi a:3 ce 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, th*l5 0go sen1swe amount of work yol* o05wse 1sgnu 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 lbk2goo ; p.8nand is being held there. How much work is being done in holding the box in this 8p.bok ;2glno 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 forws7+yh: i omowut/:e8 3h.f+ggeuut0 hard at a constant velocity carrying a 10-N object, the amount of work you do if7/s tiwoehu3o8ge:u+gy0: m .u ht h+s

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 lif39lg;6yp y0t pkxa9umted vertically 3.0 m then returned to its original position. If the total weight is 30 N, howmyyp a0 kg;99l6pu3tx 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 do8ox /htdcg m8-bl7n g( work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the s- dx zi0u:z cuau3 *vugrat:;1ign of the work done by gravity while the ball goes up with the sign of the work done by ga:- a v z;0gtu i:u1cxuuz*dr3ravity 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, o -y61wkzy h*bsnd5it.n a Force versus position (F vs. x) graph, represents yby1i-z.dk*65ntshw

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 v4wg :rdtxnpa o(u 04j:s. x), what represents the work done by the force F? ux:rw 4atd( :4nj0ogp

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 oe/9jbjw8y t6 ibject 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 ovu ng 0smecdqy uk(8t41b*z9 1)e g)ben an object 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 zeoh;bfv, ,/d(g(vcr *zj- nussc+p n8qro, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and isk5s0s rsp;885zu dlec moving at twice the speed of the car. Which statement ipk;c0 sdrszs5l85 ue8 s 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 fast as car K, and car 8 l a/h1y(t ;pufcm;lhJ has half the mass of car K. The kinetic energy of car J, compared to ct(mp;/ ay; 1 hc8fllhuar 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.,t zqe/1+ql,xpx v,ta What is the ratio of the final kinetic energy to the iniq,,1/qt ezxtx v+ a,lptial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a xake3lb7n, of 48moy/w8tfe5p y*1z vspeed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to t, tex pa8 73w4f5*bfyk 1olvzm 8yo/enhe 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 mass iso3b+8e* dvha,e9 i0vb ve8alpn5b 8to moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the gr80i,tlbb8*893vd poao5e+v eevn bhaeater 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 brakesk+j 8wru sr2 ,xys-4tc of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twiuyt s,j4k sxr-rwc28+ce as fast, what distance would the car have 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 an elliptical orbit. Negk 2v2ln w-xq6blecting any friction effects, what happens to the planet's kinetl2-wvxkb 2n q6ic 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 prinpmg2 9 czlb5nlygc* s31h8)mcciple.

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 negatruwiwp-38v wxbo en 6*zo40 w2ive 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 released0at9c8dn/om;7p q xqe;mimm ( from rest a height h above the ground. A second object witmmm9e qdi(870 ;toq;m x/ capnh four times the mass of the first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring ca6mvvanlb.kem6i 3o+ls3h6/wuses it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, t 3/3b6s lvanmvw66li.+ emhok he 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 5iokhvn7eqoalmt x3(y 0+ c.7ui99hgof 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, tcd: g,amx w9;k0m8k 5osnu6 zuo its potential ener0x nm s85,:k 9wa ougzkmucd;6gy 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 car1:k*mqebhxxnm8/k x4 - rsv4w 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 and a very )5rfgpdl 53 dwm,p,oq heavy object are sliding with equal speeds along a level frictionless surface. They b3),pm g d, dwfp5l5qoroth slide up the same frictionless hill. Which rises to a greater height?

A. The heavy object, because it has greater kinetic energy.

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses r 7:tw ov6y/fm$m_{1}$ 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 colqh 2t:m.v9;riew:dyk8q b ,mnservation of mechanical energy for conservative forces:;k2:v9ly t.8qm mr,hd eiq bw.

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 friction is d)mc s3u +ssaysbv78.ui *p(opresent), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (op7 .uamiss (y)bcsuv d+3s8*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 gai8 y k22a4l+ kctz(kgafns 30 J of kinetic energy. Do not ignore air resistance. How much gravitkytkfk 8(a4 g2lc2+z aational 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 distanc.y ksj2aer-c09omy4 pj5)b pf e and loses 30 J of gravitational potential energy. Do not ignore as4 0 y9p5k mefacj.y2jorp b)-ir resistance. How much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservatiochmsftf :d /4d 1g: 6a-:enulan 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,2z /0x njjexmgb.5i;3ma dhmo rtd(+

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 expresse)+fw t8mk* viqd 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 uni-zt(/s9/p /flhvpj c;zo:tx bh o0qatu 07 nc7t 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 onea/( un+ 5ulwi8dwge, ekj/;g i-third the time. To do so, your powe8g/ uew eun,jw+5d/ g klii(;ar 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 4;i1i :whfxjyk( -um b2boce 9a constant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If the object weu gq q)8rqkawpd+j :93ighs 90 N, how muchw9u r kp qaq:)83dgq+j 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 j malx3z o 1kted16o* 0g2,hysbook up in the air a distance of 1.0 m, at a constant velocity of 0.5z3o2ho1s*1mj,y d lax k e6t0g0 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 pulle/o 3bxfvwaz5zlohgu .7 i+y)+d upward with a constant force of 5500 N for a distancozlg3+ v)i 7x.w z+ aufho5/ybe of 50.0 m. 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 pulled upward with a constant force of 5500 N for a d qfc z*,qm*c4l l1zr+x8b )esgistance of 50.0 m. What is the xblmf*8 qsr , z4)+lcg*ec1zqwork 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 consta+:z//qe jimin:g uir mqh1j1*nt force of 5500 N for a distance of*nimhqimr:/ej/+z1g1 i qju: 50.0 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 pulledag ,osu tqf:aamv kw604g7on :25 2zua 6.0 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, incx/dk9 2mrt ph -un9t+ e04v5eyhgr: udlined 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 ing,vbk u68 mj6a a sled on an icy surface (assume no friction), with a force of 68m g,akv j6bu60.0 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.ygb 1u8adyl n6p28fm*8mb wu5 The graph in Fig. 6-1 showsl p2 amm5bw68f 1 budyygn*u88 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 thpat) 5lrscc-hmov0 ( dwr9 .l3e direction of the force. The graph in Fig. 6-1 shows the force versus arcos.5rhtl9l(0 mp wc3 v)- dthe 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 fo29x/r e1 :mh7kqz o as5g.ijf) wfhj:orce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done w2oxej :1o:fhijaq/rw.zsfk) g75 9hmhen 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 directio)xi s:)oo 6 ch5iumxw8n of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object mo cwimu))sixh: 68o 5xoves 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 (initially at rest *nca*omktnb n6jbh b+ 31c*h;*lr5bj) acn*o bcbb 56n a3*ktl; mhhn+c*1*bj jrross a 10 m level surface. What is the final kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg carw0cah pq ctmnyu0:17sj7;o d4 t (initially at rest) across 4actwp cns70d;j 7o h0q1y :mua 10 m level 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 with a speed oftl+q*+9r8u m3 jm*)ete jrd et 5.0 m/s. How much work is required to stre3 +89qtutjlm+ ermjdte* )*op 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 initiac;o o(34 n b2dnxsan1blly moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same condinbb o24 cos3(;a1n nxdtion?

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 :k5 b b+e/fvwmjkuw12exerting a force of 20 N over a distance of 5.0 cm. With what speed will the /ubf+w5kv:jekw 21 m bdart 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 vertical compon:/ wclwz4u,s( uck gw0ent 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 the floor. What is the cart's ,glswkc:( w w40uucz /final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bacru,/-ar5drx le of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the adc r/xr-5 rau,rrow?

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 akmgt6y(r1 c1 *)xh sbfmgy8 8nbove a floor to a height of 13.0 m above the floor. What is the change in gravitationax 6g*s)y1r gcm(btm8kn h18fy l 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 inclieahud4m5uczx:a 307(o.t s wz ned plane. The plane is 4.0 m long and rises 2.0 m. If the plane is ft s ha3c :u5.zem0x 74(owuzdarictionless, 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 spring, causes the spring to stretch 2.0 cm. W4xs :r,eh, iihhat is the sp,r heis4,xh :iring 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/ ckm,6 -b 3kc*4 gbkj,dyfjh1o8hf4 ahm. How much potential energy does it store, when stretchedjk- c4o3khycdmkhh 18b6 bf,ajf ,g4* 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 uncommbg ge0 ffc6 xxm181m4)nclf 9pressed spring with a spring constantcf6fmn81fg0xc 1m)4l b9x gem 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 spri4 y i1shl6np1iht :w4kng constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the u1plwh6:niyi 4t4hs 1k nstretched 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 constanh ji4r1xsy )x6t of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an adry4j16 hs ixx)ditional 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 s*d/knfda9( k zlope. What is the speed of the slier on reaching the bottom of the slope? (Neglect dak9zn(k *f/d 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 te4j+5/ p6 *utilhkw9jy d:db g;h,jbmop of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving afb6 j ;t 5u 9wg,l+d/hep yim4bjd:kj*hter 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 frictionzr8( + u9uyltmzw76;s y/ vl wvf2,yxzless inclined plane. At the bottom, it has a speed of 9.80 m/s.t /lx slu6+,(2vmrwy9fz8v 7wz zyy ;u 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 aboverq zucjvwf pd-f7r-b+)/0he fdj:6r* the floor, its potential energy exr):b-cud jw +q*phj6f e- f07 zdr/rfvactly equals its kinetic energy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blecw 8 czq7nijn z-y ,-4y4z8ubasts straight up from ground level with a kinetic energy oy ze8qzy ,cic4jzb78n-u-4 n wf 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 ki1s-fxx 3r: d 7kthf-npnetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J.:r-ks thf nxfx1p-d7 3 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 bottom of a ybl. :l c/nuzx.hxf(2 dip (See Fig. 6-2). Neglect friction, what will be the speed of the r.f2 zhxcy.bu /:n (xlloller 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 spekmyiwxk kc 2, lz(mj+fzi0p 3,gm,/7ued of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottox/kz,guily wzc(,2mj ,+7m kf im03 pkm 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 3rax*kv.) jug. nbn02 ygidfdz:p9 w0,0 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 tngx rz:i yn02a9kjv g.*d,).d0uwfbphe 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 bagdkk4lrli; 0;q pv8z .ll at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and re ( etxqp78oqg1leased from rest. What will be its speo x(p 78geqqt1ed 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 initially :r9h mrd 2:nim4dkio:uncompressed horizontal spring with sprdr9 ohm 2:im kdn4::iring 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 h i1b,qytyhx6z08 kik49dg+qx5)hwup er 2000 kg car to stop for a red light. What work is done by the friction forcq) zy h146d0t8x,x9k5pug qhbkw+iyie 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-kg object:*dk1-fisk ywhubqzb n3 /)kg. +e jx. and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?yz)b b.ej/k:n3gk+.-*1 wdu iqxshk f

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 rou9s2 e)qt6cpwnzac( 9 zgh, level surface. It has 24 J of kinetic energy. The frictionw)tq9znc69cpzaes (2 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 2.0-kg mass on a level surface. 43 va.if xgmv kc1pu9+The coefficient of kinetic friction f 3a +x41vuvk.9pmigcbetween the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-8 pqepsz2f ;f3m high slope. If the work done by fripq;8f epfs3z2 ction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. h6;g x .shw(7rr.s bja The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average frictios .7(6bxwhr. rja;hg sn 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 6e n;smd,kdjwr4-6l ffrom rest at the top of a plane inclined at 20e above horizontal. The coefficie med6ks6lfn;4,wjdr- nt 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 hscdci;7 v0 i49qxf vngcu8 hc0-9)xjd eight of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What av d 09jxgcid;f)i xs 04 -c9hvqn8ucc7verage force of air friction 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-kg boy using energy when he runs up a flight of stairf:aasl;2 vf/b s 10.0-m hig afvfa s/2;bl:h, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity o 3;zsa1wuo:jz f 5.0 m/s. What power must be delivered to the object bauz1 j; 3:ozswy 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 b kgixq wxjy5kq.82(.ly a 1.0 hp motor that runs for 1.0 hr? (1 hp = 74y52 qkw(xgkli..qj 8 x6 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 forc7kbbsnb9b:hp3z-i. 5 a .cn+ emxj9zbe does her foot push with when she is trav 9b 7bnc3s9 zx-b.pzb b.k5:n+em jihaeling 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 accelerateb hgwp5)*dv9tr nh g(,s from 0 to 25 m/s in 7.0 s. What is the average power delivered by the engine? ,9r5gng) p(hdwvt bh* (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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