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

1#

What is the correct unit of 7j z83k0g,i 8en nvxbmwmx5u*work expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on z ozr in w(3z(koj;j9a;jc,s* a system 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 harm(w wo+igk ,;nkq +x*wd against a stationary brick wall, the amount of work you do+ wm ,kin* gwqw+k(;xo

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 he/gl+zbx 7y t7u2l t+;wooyic) ld there. How much work is being doneb+g2 coluwyx /i o7l7 )+yz;tt in holding the box in this position?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forw: nel3n4y:f q n2kdge9-(rbx dard at a constant velocity carrying a 10-N object, the amount of work you do is ne2r ygk4:bqxf3e:nd9(dnl-

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 returned to its origi l0 bb:f t5sf;8dy+h9 pw 7oqbo,q.aapnal position. If the total weight is wyb0q o,:7ah ; t8 d+ob9fpqsblpa.5f30 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 9l* u:sp.u ymhqgkj )+object do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. C ;qjai+ *9f7zis,ushxompare the sign of the work done by gravity while the ball goes up w+u; , jih9zxs7is *qfaith the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus positiolr,;vxy ( -cvxn (F vs. x) graph, represents;cvyxrlxv( ,-

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 vsp sy123lwaa6il,xau1. x), what represents the work done by the forcx3l ywa6la 1,ip1s2a ue 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 positie rbzkc9b(gz v2 b6jhl4p h329ve, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, thgpj pg 1h+yf/:c jf7u5en 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, tk lx m+*e8fe2hhen the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at q 1ekmb/ j *h-+r87s776lpjojt;uddjx wih*dtwice the speed of the car. Which statementtlws *j/e +upj bdqj7r-jh iokdx1 76 d87;mh* is true about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of car K. Thajfi 4opn0zi):5 pq bi s5 n02io;gl+se kinet0jfa pz+q lsniini s5)04 ogibp5:2 ;oic energy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with halfu f l*(xr2f*rp2o,tve of its original speed. What is the ratio of the final kinetic energy to the initial kinetic envuxr p, t*o2e 2fr(l*fergy?

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 k*ldg)k k upk;).x7*8 9.az rz blsadlpebble is moving at a speed of 5 m/s. If both objects have the samp7)bl8lkzk 9sr da*a.xl )ku;dk.*gz e 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 mass is moving with spe96z+eyp pf:zlmdtep3 ;9 i0ze ed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before lmp 3 0zzy9+:pp et;zid e96efstopping?

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 yourw+mw ql yjgx(hah4 -:) car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance woj -xywq)h(hlag mw:+ 4uld 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 o*xpv9u6 q y:+1qwl g +9ade bj2rxob)elliptical orbit. Neglecting any fdblx+o 9vo brq+eq1 2*gaj9w6xu:p) yriction effects, what happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy prinogixs2wa khnsw z 8a* ://d;m.ciple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have neh(a k z:c12mfrr 3:wk:z0absegative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. j6 5 - 6zlgzqcp+;ge ch,po/wiA second object with four times the mass of the first if released from the same height. The potential energy ofpewlh5 ; cqcpz+66-g izg jo/, 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 causes it to stretch . fsfyb5t .2ll.n3bxg5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spriyx3l.tnsl b f 5.fg2b.ng 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 of a synuv(4p6vcg0 p stem

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 j 3tpnl ,qg.v1qh*e3hK, to its potential energyhg3t . j3lhqpe1q*,vn 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 n-bxy 1sv;1y c;g*hmq +ndkeu0b a56 kdriving 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 h s:jggbx):9 ;7qutqw ceavy object are sliding with equal speeds along g jqc:w sx7bt u)q9:;ga level frictionless surface. They both slide up the same frictionless hill. Which rises to a greater height?

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

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses + 8o/m:rxydxk $m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical energy4m,/k hm*mz4yaez8bo for conservative forcesa*4hbo8,me k zym4 m/z.

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 pre65hy/ 3xak auym;zk8i sent), to the ground below. How does the kinetic energy (K) just before str8; /xi y3h 5kk6ayzmauiking 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. Do notfq( o4iy9;jm a ignore air resistance. How much gravitational potential ener (9ym;q4o jaifgy 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 an skn;1kx33tru d loses 30 J of gravitational potential energy. Do not ignore air resistance. Hn1 tk3sx3kr;u ow much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation s (o.2 cy1ndt1vyhv p5of 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 ism.u,lwg+i*q4t obw tu z 6q0+h

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 o;z (w +u:oi/tsa:whyd2c w5 vkf power expressed in SI units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit ofk.)l3-dw,m4 gala.h ud w sp2;y.txfe 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-bm6qb26c.+wnq , u kuxm9dz p3third the time. To do so, your power output mustuqzc. u db6n3b9qp,62m+ xm kw 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 constant acceleration, the car*k 3esj- j*cza +0unxu/+o2s( uvjqqq'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 objectj-l b qs 0sj4r1gy8sj2 weighs 90 N, ho2y10qsss -gb 8jjr4l jw much work was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a diu8k,6 gg8nak naomnfg*ej-41stance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done 1ko 6j a ung*nam,8gne8g kf4-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 wi r/ eu4rfse1)hoxtp 2.th a constant force of 5500 N for a distance of 50.0 m. What is t e1/ he)p42fust. xrorhe 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 pulledr ;*jliqnlx mrx9;( +e upward with a constant force of 5500 N for a distance of 50.0 m. Wj(n r;ml9r*q;el i+x xhat is the work done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force 9-id;2 8-rfj pj(txipu:b vrw of 5500 N for a distance of 50.0 m. What is the net work don8rr j-b wppjx2f9v(i-tuid; :e 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 *7qie24 xt*xbh +hwpu6.0 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 8.0i 0qj8sq8zh4 r 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 i7 9e i pt(ie8-fkqtg/7f0 zkchn a sled on an icy surface (assume no friction), with a force of 60eq fi0-e z7hpktf8g /ic(7tk9 .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. Tk bjmtn c of+)x 88cql+q--1qehe graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the oq8oc ) --nmcjx1 l+fqq8ekb+ tbject 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 dfdj u uy5e85wvt +6)d7de1cmpt*b ( izirection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 2.0 to 4.0 m.() u55d6ee bdw*7m cfz 8ttpvuijy1d+

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*rf+ r6w)ry ;ee1y wmk in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. f+w m6kwyr1r r *eye); 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 force. The grapp f8 tm,goep74.yo( xuh in Fig. 6-1 shows the force versus the object's position. uf8xy. 7to, ( pe4gpom 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 (ia:v.4 hxdk;en nitially at rest) across a 10 m level surface. What is the final kineticxekv4 :n; da.h 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 55vxe f,kt+ b(/d uyo,8wbwm7vx ,e1e,z-kg cart (initially at rest) across a 10 m level surface. What is the final speed of thf,, ,bo (vzw m8e e/ ,ubx+evwy17xdtke 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 wolfeyx 65m38asc a 9v2b;5te xj j2iur5rk is required to stop the mass? um xjf2sael95taye8 vjx2i c5b6r;35

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/sry, oe rm qjht+ rnlnr0*u6* jl5y.p38, what distance is required to stop a car moving at 50r8y 35lemq*tj6 r0yn.pu,h rj nol*r+ m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is coc/qzd13dt z;g3 qrso)k m0yl/h ked by exerting a force of 20 N ovedoy lqsz3/ rkm;h/g z31q)d 0tr a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 r1xmy ji3z4j, kyb a27vl-p7j N and a vertical component of 60 N. The force is applied to a box wj 4ykyjr1-bal z2p x77 imvj3,hich 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 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 bale of ha;n5/rzqj s(sty, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping fsq zr (n/tj5;sorce acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to a he odupm3.iy )r, (3 i -dudrgbpw/1+kvbight of 13.0 m abovu(+3.dodg,i-vyb1kur p wdip3 ) mrb/e 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 upgl5oq tp0m 5(k1sgy10hq m1af an inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictpqa5m(0tlyh 1g5q1g m 0 fo1ksionless, 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 sprind+13d ujqmu y;g, causes the spring to stretch 2.0 cm. What is the spring co3jqyd1u m ;d+unstant?

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 consta92 uxcc7nys:q nt of 60 N/m. How much potential energy does it q cxs:72cn9 yustore, 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 initiallybsy+ 6 )/-lsls :woieuw:tky/ uncompressed spring with a spring conlu / l /tye:bk+ -so)sywiws:6stant 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 constatz1u ;kpa- oz;nt 40 N/m from x = 0.20 m to 0.25 m? (Assume the unst;pu-zz1k oa; tretched 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 constantle60c2/ iru om of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an addu o2ciel mr06/itional 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 slopf ;-z9zeqh psmzp ;;x;e. What is the speed of the slier on reaching the bottom of the slope? (Neglech;zp;z9ez-fps;m; qx t 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 inl+a,ibyy:cg ;r 8mt,3 ke :gqg7gs5 zxitial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after droppizs: 7k ag: ligg3e,,+b5yxct ;qgyr8mng 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 incli d r eoa5lc/1(rba-,enned plane. At the bottom, it has a speed of 9.80 m/s. What is t ale 1/bn(cre r,od-5ahe 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 yg8 o+9m0n 7epaxv)tgdmta4).70 m above the floor, its potential energy exactly equals its kinetic energy. How ottag)8m4m ng 0 vexd)7a+py9 fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straizk5p-a8hyub,d7vy q8mg + s+qght up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical heightqk mv78y,phg+dzsq yub-58a+ 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 wi1uyaafq)fk 7vey * d2:th a kinetic energy of 220 J. At the highest p vu 21 7adyf:aqf*key)oint in its trajectory, 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 fromq/ m(:i) stno;7xrknd rest 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 bo) ms/n;(:ni7k dqxortttom 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// .kx;df+t uvam1utk *s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect frt.* vu;x+ /d tmfuk1akiction, 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 ofavgq1 f;uz+/ c3svoo 8x 7 7bd9y9dxjk a dip with a speed of 25 m/s (See Figboc zv+1j98/xy u 3;agx sqd7kvdf o97. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of dp*jueh00wwh.n1t*0 b6xbgb 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 pendulum of length 50 cm is pulled 3.;h*uwjot o73wc bb9z0 cm away from the vertical axis and released from rest. What will be its speed at the bottom w bu7hb*ot3w; o9cz .jof 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 uncompressed hox +(hkaunvs48rizontal spring with spring constant oskvu48haxn (+ f $2.0 \times 10^6 \; N/m$. 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 fc-y7cy/,qa z a red light. What q -zf,cy7ay/cwork 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 between a 60.0-kg obto 5ort4bc0 .pv2nb9kwp 2srj+qh -p6ject and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance wilkcb 9po 4trq s jo6t2bw5+n02v .p-prhl 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 ener wgi*yh:4 bp*cgy. The friction force on it is a constant 0.50 N. How far w ychi*gb4*p: 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 1rj-3 fiqj 3trpclli3 v40xf.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 rl13f xp04il3q ji3c.f j vtr-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-m h un(86pbkbu1 nigh slope. If the work done by frib8n (6bp1nk uuction 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. The plane i /y *bpeqjfd:8s 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the topqydb*: p8j /ef 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 reh)gse+cn4n q-st at the top of a plane inclined at 20e above horizontal. The coefficient 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 ths n+4nge q-)che 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 2w:dn,d:; yp1kkb fuv10.0 m, and strikes the ground with a velocity of 7.00 m/s.::v w ,p;2fnyddkbu1k What average 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 bou s08skzry9wv59 irg+6usop ;y using energy when he runs up a flight of stairs 10.0-m s u+g9izsrwu rsko65 9;80vpyhigh, 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 needed1cj5fmhbpr v )duc( 461(+aij. ovsb r to move an object with a constant velocity of 5.0 m/s. What ) cvpu jh dbv.(4r( a1ficrob1 65+sjmpower must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs for 1.0 hr?q+ic0*tyqdj51x rmy + (1 hp = 746 +*5+dq imcjqty1x r0yW)

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 ;(m*p.qjl1 ps usao (aforce does her foot push with when she is traveling at 8.0q(pa. u la;1o*s (sjmp 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 thh3s.+ frfrzh; e average power delivered by the engine? (1 h. ;f fzhhsr+3rp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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