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

1#

What is the correct unit of work expressed in ha-(pr)y+xt2 7ziq mh SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there ik rd r5-7s.c-guvdad* s 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 woi:0,phjx0 ux zt6r7obrk you do,pri:7b 0hzt6ojxu0 x

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 helmk8 rns(h vhed +cy ;5,yar.b/d there. How much work is b,5b/ n;s d(ce r vyr+m8hay.hkeing done 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 forwardg*h8894r lbigpkwp y8 at a constant velocity carrying a 10-N obj 9b*4phr plgi88kygw8ect, the amount of work you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returnqs2tn*yrd7 cbro+pk4 x *pf cy46kw+n y658g yed to its original position. If the total weight is 30 N, how much wor6yct ns 4qx5cbrn8 p 7wo+2dk*+kg4 * pyyfry6k 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 p xw/ q+q (ve th2kiluc:.t7m8g iid3/acting on an 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. Compare the sign of the wo- 4ulmrs37(tmbkf k o4rk done by gravity while the ball goes up with the sign of the work done by gravity while it g mfm 4r-tlsbko7u4 3k(oes 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 versu s-vjb/i7xarmzl b +m 0u-)y7zs position (F vs. x) graph, representss/a7zyjm+bzl x) r7- -i uvmb0

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 b+m+sdii hbs *vai/3ryo4/ :n (F vs. x), what represents the work done by the foy b4o/3idvrsami/+bh:in*s +rce 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 done2jrg1 8xiq3rh* b 5haw on an object is positive, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then the object's ksp qs4v *pwu)+8/nfi ginetic 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, thebl xg- p4pb2tjb,c3,d n 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 i )k8bk 3lnlvqh292hp).xln* ;enysd a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of the9q l;2nx ikl)hv py8b.)hsnn l*e 23dk 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 caqpy 6-lcjv2pgal64me)3*g ayna (bn 6r K. The kinetic 6ej4cnm2pl(lgva6pb)6gy *- aqna3yenergy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speeucl.wru0r8o4 d. What is the ratio of r8cow u0l.4 urthe final kinetic energy to the initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed90 fo 1 r ,yhqn6eua*so-zql-k of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's sry1-n6ol a*-, hoquekz f0 9qmass?

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 spu cjo gp3,vb(snen p;pj9 3/w2eed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greate9 p3,pouc/vwen s 2jb;(nj3gp r 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 ski z lhk0k3q53xpd a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skiq53 k3x zplh0kdded, 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. Neglecting anyjq)lb 46v:za5 q +bfzu friction effects,jf+ abzl v6 q4b:z5)qu 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 principl;yihvg( f0emlb 3q + genp,*q7,/wxdee.

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 qp-/zn 7h rd.bpotential 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 abovt ic:.mg(j*mw5a6e)w:cdo)p 7,uww hg aa 3tte the ground. A second object with four times the mass of the firsmwtpu.gtg:ecaj a65,ih(7w dw c:m *aw)o 3t)t 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 attachede-/y l *waw.x-(/ hlwxfw mxq6 to the end of a spring causes it to stretch 5.0 cm. If another 0.200-kgwlxaw wq/xx/-wmy l -hef 6*.( mass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a sys/vhs3ymr9bk 4 . a8)w-lbxqnwtem

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 ener32n wn*8i jdkoohg/(l4t evqbm 92e)ogy K, to its potential energy Uwo(ntlih 8vb 4m 2e o3/goen9 *jqd)k2.

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 drivis1em(.x(ho;znmsg + ws. iqdwkmx*+0ng 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 anf lj:i)ockg + )w0bp9sd a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill.kwo:c f jspilg)9b )+0 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 0 ; hdzeghcbhv1t25:a$m_{1}$ 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 energy for conservativo:p 6l 6zdint0 x*- r+8hzktxge forces.-z :z*ogkh0xtp dnil66 x+ r8t

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 aih6z11) fmxszt r (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the grzsfm1t1) h 6xzound 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. Do4*8al2sqjjz dpt3/ra9 * mjp j4zsv(q not ignore air resistance. How much gravitational poj24/jrmtq9lpz3j8*vps 4ja *dz(qs a tential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and lltuyaj8i q5y (:eg x,b v)dxw54uh7z 3oses 30 J of gravitational potential energy. Do not ignore air resistance. Hob7uizj) 345y axh 8u5gvxde:yl q(wt,w much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservat 2;on1ob uq)ahrv8v cq./i6ixion 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(ku3) d13gtz xyr5 ghv7d-lsf

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 ex85v cu.* qqsxsyhq68f pressed 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:tweem63e h* e 5;9mk/ tjt(djxti6 qt not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the qh40yt+t hy-x hj14ujwork in one-third the time. To do so, your power output my-y 4 jhxhth0tq 1uj+4ust 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, thb6sz-8jb m-jee 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 andhpp(df9vi5v0s 8 xik 7 held there. If the object weighs 90 N, how much work was donk (h 7pi5fs9dv08i vxpe in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at a+,05fond f my2 )p2x p1ifbqsz constant velocity of 0.50 m/s. What is the work done by the weip+odzx,fs)5 0f21inyp b f mq2ght 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 constant force of 5500 N for a r yk6c bpmk4+vw 8ha24distance of 50.0 m. What is the wh yp42r6mwvk8 +k4cba ork 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 upw ./6ik07h q hu3c71 f,zfjktkqgiqsk*ard with a constant force of 5500 N for a distance of uk1s.k ,fq7t3ik cj k hhf/qgiz6q0*7 50.0 m. What 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 fo8w0dr 5yn +idtrce of 5500 N for a distance ni0ydr5tdw + 8of 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 pulled atz3rc5rxcv 4jxb+, s,;.pq6rhl q- m6.0 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 rct3; p.ljgx)p9 aiibz mfw( 41amp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy surface x- 8na6n 0 0gph1ppitogug6+m(assume no friction), with a force of 6tp8ouig x-6 +gg 6nm01pn0pah0.0 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 of1*4 a8ect) 0 5qknkzws b+ xcqvba+ievk90el 0 the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work da 9ev1 400eqb 8 cnectq5ilxvkakbk+*szw0+)one 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 d,8 3jstmeh) z epcafy5g (kd5;irection of the force. The graph in Fig. 6-1 shows the force versus the o;j m fdc gy)3z ks5hpt,85ae(ebject'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 forgyl1l.x lg2 9wqk-p tq6;0 el 3kxso9hce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work3yx6h k1gxwt99-;qllp oe kq 02sgll. 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 thx d.a a)8-oetve direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done-dx.)8to ava e 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-k)*zlzu 4 n9e-ftq,gvf g cart (initially at rest) across a 104-*q,)z lfeunvgtz 9f 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 cart (ihn i( jhuk5)8l ;yrp6mnitially at rest) across ar68i yp l (5mjhnukh); 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 of 5.0 m/s. How much work is requi0fd jirf+trypa)p/ ,72uamvoc 5kp*. red to stop the mastp.0j,pd2yvok aa+p m7/ fui)r5cf*rs?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance is+h1zzq+3z e0uk;r1/afrka w a required to stop a car moving at 50 m/s under the same condifa1uk h aa/ r+wz;z0q3kzr+e1tion?

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.( )dmtp j2xhj by exerting a force of 20 N over a distdp)m( j.hjtx2ance 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 oq h s)l,up:0ikf 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart staps,lqi u h0:k)rts 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 no4ob,6uaj* p bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the averagb6 o,n4jop a*ue stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 mb tyrqob ++0*qkq-q*y above a floor to a height of 13.0 m above the floor. What is the change int+qo-y *b*yrk b0qqq+ 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 planedme(t)d1zhf5c16 y*je 9gpt z is 4.0 m long and rises 2.0 m. If the plane is fric1 6(ejt)de1zhydt*c mpz5 g f9tionless, 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.h,6cp:yfi q7ty52s q r What is the sp57 ri:ct 2q hfys,q6pyring 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 co7kvmk x/ suhy6 9jg*:snstant of 60 N/m. How much potential energy does it store, when stretched vm k 9g6kxhy7*suj:s/ 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 a7 pqu 93v.d/ssjg*yjaz6 /jwen initially uncompressed spring with a spring constant of 25 sdqjwuv ejg .9sa*3yj// z67 pN/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 of94op(1ptil u+ /ihx f,df 7hsf spring constant 40 N/m from x = 0.20 m to 0. +h o1 /,ufifpf(ils79pxthd 425 m? (Assume the unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring cons:d0+iih 9+uh qkta/z btant of 15 N/m is initially compressed by 3.0 cm. How mu90z+ :tbq +hiaiud /khch work is required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50 2q umo(6 zeae ac0,64vgk+zbp-m high slope. What is the speed of the sueb 46,q+ z6 a0vk apzme(2coglier 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 2 au5- b,mdcxz1 kem :e9ew9zlwith an initial speed of 4.0 m/s.e9z9 c1:zkl,e 5b2md-w xmeua Neglecting friction, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined pla)t(x3i0 gjahc 0+ /dbq*rtnejne. At the bottom, it has a speed of 9.80 m/s. What is trxi0j+jt h(n30b *etc /d)g qahe 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 floor, i 6 2m vxz-i4( iwesc6n,s9mfalts potential enervx s(afizn6i elw6c 4m2-m s,9gy exactly 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, blasfp37 o50 qyxxcts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajecf7 xy5c pq3o0xtory, 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 kinetic enerde mmg-/jbm6.r: svg 8gy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it ri j ggb.s/d86e vmm-:mrse?

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 he 8 2ukj8iiz 677(fojax0z ecat 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, whif7cjee0(kh276z oxauzj8 8ii ch is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at g2kroqa-6 p ws,i8+ eka point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the rolle6q2+kpw-8ia,e k ogsr r coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a d o ;nzbid5k,ip*8j +bfip with a speed ond*8i jo,p;zbi fk+b5 f 25 m/s (See Fig. 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 the ball at the botofn.c*+x;an ktom 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 awayw2j.t 5k;w 8aejl9mk b from the vertical axis and released from rest. What will be its speed at the 2bwtwml;e8akj.9 5jk 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 ank-j:jpr s0)pd/ua pi/ initially uncompressed horizontal spring with spri/kpsp/d 0jr a )j-p:uing constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her*y2 of8djav7xs +i:a .,izcg+lmd9jf 2000 kg car to stop for a red light. What work is done7idz 9,i*ma 8d fcvxo+y2:gj afs +.lj 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 forc4a6o t6rct.81nzde n ce between a 60.0-kg object 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 ben4zto.r t66denac1c 8fore 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. Iwenc w;fmwq 7.w ,7di:t has 24 J of kinetic energy. The friction force on it is a conwdmcn; .wi7f :w ,7ewqstant 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 t 87jrdnbl l6;surface. The coefficient of kinetic friction between the mass and the surface is 0.208ln7 jdtblr6 ;. 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 startsob,;xqhy0y *d )z qo7g from rest from the top of a 50-m high slope. If the work dxqy*oo y ) dg;,bz7q0hone by 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 inclined plane. 0 .gd1gja r9cnys9me9 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 magny99 erngcjm sg1a9 0.ditude 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 atx4+ ka 6ynq+nu 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 thn6yq+a+u4k xne 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 v (5t4rx xx3xbfrom a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air fr(v4 xrbxt 5xx3iction 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 60.0i7xt etjb b+09.r4zuqb : 2iib-kg boy using energy when he runs up a flight of stairs 10.0-m high, i+t .xruzt9 bqi74:ij0bbb i2 en
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 tokqei7s 1e x) f30,yhdw move an object with a constant velocity of 5.0 m/s. What poyf 3iexd h 0,e17k)wsqwer 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? (1 hps(kqumg:i e9t(+eb wb,gh- :w = 746 ge,u hb((:m w+ iwse-kqt gb:9W)

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 koioi.uo ha5a+/y(;o the rate of 500 W while riding. How much force does her foot push with when she is traveloaa+uk ;yi5oi h (.oo/ing at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7y5*)vi xb.o hi.0 s. What is the average power deliv)bh xyo.i*vi 5ered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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