Physics Unit6: Work and Energy - 51fly国际课程 (51fly.win)

1#

What is the correct unit of work expressed iy pd5ym7z-)aj n 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 syst:,z61( :adtvhrn 1:qe1gzpmscc( z ca swv-v;em if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the amount of work y-7, wp ays6tvzou dostyz-av w6 7p,

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 lifte)wn ve,su oae*kee- p (s(gadi3351 sud 2.0 m vertically and is being held there. How much work is being done in holding the box in k-sgn(e1 sv( )*u swoep ,5eau ae3di3this position?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constant veloc c hdl7xij +vbs.:n5:pity carrying a 10-N object, the amount of worid x:nspb5v:. 7 ch+jlk 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 rett+p n ybgr4j 6:v;(lfeurned to its original position. If the total weight is ge(:+b lnv 4 frpy;tj630 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the objecd1l oymud6v9u igf*09 t?

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 work done by gra9(tj:)cvldmm/ u gi l9vity while t9lc/ljv9t ):gmi (mudhe ball goes up with 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 position (F )ml non/3 zp1ofqv1wyijap1h1b*.c .vs. x) graph, representsv p .1o)zq/ciw 13fb*njy1hp mo1.l na

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs.a jeeh-x,qxvhan8jkvw4o z:6 f v2;64 x), what represents the work done by the force Fj2 vh8x:efna6zwkvaq6x ;e-o h4 4 v,j?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object'skkmnk5 ) .uap/8h8nze 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 objgo ksy6g 770uil rb.e/bw4o e2ect is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the object's kiecd (85r)ub gonetic 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 molc v7ndh f*6+e3(9rgm- jsiplving at twice the speed of the car. Which statn (jr*c hemv-+p6sgdll 3f7i9ement 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 mass3 :/2.;wmc j/th9t rdq8iudzc6cx n ilu0tnw0 of car K. The kinetic0 2/uutntdx /6i:rncw wt.mh0 zljq839ccid ; 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 half of its originalgho( * *1gzjdy speed. What is to*g( *djyh1 zghe ratio of the final kinetic energy to the initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed.fu(-*pe6 7h5e ayg exazr)n9.olh rc of 5 m/s.(uz9alee r.7oyga f) .hrcn-65*xpeh If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is v o55wh v88mdrmoving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. wvo dhr5858mv Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakeb66q6;l a gtnmxhzj50s of your car in a panic, and skid a certain distance on a straight, leveg0nja ;l6b5xzm6htq 6 l road. If you had been traveling twice 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 thhbe,9dn/rc3f + alzesz/,z zugw5/ j:e Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic j/ez:+9eh d rcz,lnz gau/fwzs ,b3/5energy?

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 9ltdfi4fgr)/principle.

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 sys o,,5+ozlfjcp 73 xggetem to have negative 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 *md*((.oc kwt k nig w6g)p5dfh above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second obdwgi5(c*kw.)ptd ( kgn* f6omject 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 5.n ,mfyoal6uns97) i9v0 cm. If another 0.200-kg mass is added to the spring, the potential ener6m ,n invl9y9 )saouf7gy 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 enen mzg+-r 9qsy+2k 4utcrgy of a system

A. is equally divided between kinetic energy and potential energy.

B. is either all kinetic energy or all potential energy, at any one instant.

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to its pve0 k4jmgq99v otential energy U.09v4vmgq j9ke

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 driving up a z qihwlq;o f* 13bjqnptcmd 1,4ls+1;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 heavy object are sliding with equal -l*cpnl( 3pvwua e,u ,j9i;mxspeeds along a level frictionless surface. They both slide up the l p* j niumxpcw,,evl(a ;39u-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 wfcr ou ,kfq3la:i, vf4s/pn9 ty)s(/$m_{1}$ 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 o fyij l ct :uy9ec *i7btj)),mdyaa *ee-+9,hxf mechanical energy for conservative forces.iflba-9d,iytx 7+)eyem9 ,jt*c e j )yuca:*h

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 (ywveg6ziqvs z-44 +k7air friction is present), to the ground below. How does the kinetic energy (K) just befo s ve6w+4qgyzz v-k47ire striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and d+h bj9xu(;haq p1y7wvq0y*5wot xv4gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential ene *o axyp ty4+w(9xubv5wh1v0qh7;j dqrgy 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 loses 30 J of gravitational pote ,kr*ya fxn,(lntial energy. Do not ignore air resistance.y, l*fn,kax(r 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 consero/ 3pazgy,i():d: h(fpnb+x sks wzq+vation 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 isd9u6+guft/h ve * 9hg0 fxcys.

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 expressed 7wap/ ga:hi+vin 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 o4i 9pku8 h nqh5vgzw81f power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the time. Taj9*kwvw /vx .o do so, yo x avvjk*/w.w9ur power output must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, the car's engineb5emex rtirm631o s 4e ,s8pt7 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 wesglxovz * i1ft(/m4y v,0h4yoighs 90 N, how much * g,oi(/10txl m 4hsf4yyzvvowork 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 botef ,cvt7 n2r3 m1dbe9ok up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by thef e,dntter329 bm1cv 7 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 witq*tvlnxhq kmld1wy a5ni)/3 .b)8 aq3h a constant force of 5500 N for a distance of 50.0 m. What is the work done by n nd1 l*a)hl ym 3bq.t5wi83akxq)/qvthe 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 up/rq3xgo.;7 b ckgodlh7z,pxb( 3 iy9 nward with a constant force of 5500 N for a distance of 50.0 m. What is ix7 d y,;3gb oxn.qk(rl7bp/g 39chozthe 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 wio9vp9r3lp /sx 5n aou-th a constant force of 5500 N for a distance of 50.0 9xl5-vpr noo3/ 9saup m. What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up along a o/1*m1ozzkak- ve+ao ue4 kx+$37^{\circ}$ 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 h8o (4 cl6pemsramp, 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 vag4tv-j fr-7 6dr it+on an icy surface (assume no friction), with a force of 60.t6ajgivft4+d -- rvr70 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6-1 4u+azx;os h2 t lp-1dn shows the forc -2; xul1st pa+zod4hne versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the fw .vraiu:s-:t orce. The graph in Fig. 6-1 shows the force versus th:usi v.ra-t:w e 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 objeu1/zbp-jp 5z/ yzud8pct in the direction of the force. The graph in Fig. 6-1 showu p/zzj51zb8pu- /py ds the force versus the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. t,ziokjyw c()w-) qy, The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves fkyt owy) ,zqj(c iw)-,rom 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 mbp c3b**a /eob-fggz5ove a 55-kg cart (initially at rest) across a 10 m abb*f g/3p zog5 be-c*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 200a8z csiyr7z/yt4c34 w N is applied to move a 55-kg cart (initially at rest) across a 10 m level surfaceas47/t4cc y ri3ywz8z. 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 mu8 + yk92mgbvzjch work is required to stopgv8 mz 92kbjy+ the mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, who97i t;,z rewuat distance is required to stop a u 7,zi r9ot;ewcar moving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is cocked by exerting a for u:s q k6,l-f*uyj0oupv17qbng8uk 4yce of 20 N over a distance of 5.0 c6luqu,qp- gukys1v7 :o 0 u4 8*bknfyjm. 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 N and a vertical j/w4 5fbpoe- rmz;c(bcomponent 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 me bpjfo5cr(-4 /bw;zm 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 o*3crxmst* he lx7 hr58f hay, striking the hay with a velocity of 60 m/s. It penetratcmhl5** xs xhte387r res a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to a height o7 +knop2yf8 (v.fj oref 13.0 m above the floor. What is the change in gpr2vk7j.(fo nye f8o +ravitational 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 pushe2yt(kcl()pme-v(l yw)x)j gfd up an inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done by thepkfy-y2g l)j)(tc m) lw ((exv 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. vnrs1q iedq,(; m/ pb es-7 ldgas) s8l+4mck,What is the spring constantslnc ;s8) d4mvg+ s 7iqb(s1-pee a/lr mkq,d,?

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/m. How much potential e omsnl)0cy.f9jvo i( 7e-1v ahnergy does it 1lhvnoc- ea v)i0 o 9ym(.7jfsstore, 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 zwi61km4r bin6/ioo8initially uncompressed spring with a spring constant of 25 N/m by i8n iko6r1b6 imoz4w/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 s ) tkb.8x/irqbtretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume ther8 t)xbb qi.k/ 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 constantuf3qg 5qud6 d6;xr qyoht./d4 of 15 N/m is initially compressed by 3.0 cm. How mutqq ru h.dg fy;5uddo /364q6xch 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-m high slope. Whaty6zhi(ni m n6(95ypj g is the speed of the slier on reaching the bottom of the slope? (Neglect frp6 (y5 hzyjn9(nim 6igiction.)

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 initialrr f 0/ltx* .mlz31:6lzvedgl speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m in elx.l lfz0 rl 1/6dm rzve*g3t:levation?

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*wey u5z8 3lcone. At the bottom, it has a speed of 9.80 m/s. What is the vertical height of the placl5eyo3 *8z wune?

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 -jei / g-g(ghqonl 47r3yb7bjthe floor, its potential enerrhg3e jb il-jg/7bo4qn - y7g(gy 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, blasts straight up from ground leve7f1k:n vsm7rgo/m a7hl with a kinetic ene :7fh71vak7mr/ msnogrgy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leapi6v is 26t4qib1og .wves the ground with a kinetic energy of 220 J. At the highest poin.iwogsb t6 6ip4v1 q2it 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 fro 3d 9wq kigrv:1ozt.)nm rest at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect frictvtd) .qg kz91or3inw:ion, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m above the bot;z4 t3mg/c3d o9gon3gddzf 7x tom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster and o zxg gf973d4t3 /zocdm3;gt 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 dis+rt ke/f73j 8u, y8mw kkp2n1zf p+rdp with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above th+f,p y17 ms+fk8zk2 j3t kp/nu rwd8ere 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 txx-8e+e6h e3 iv ;qx c+ay6fyzhe 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 oinubq*0 5*7 i p*j9o- z.,hd tmfooonv 9cm:uaxis and released from rest. What will be its speed at the bottom of its swingvqfid0umci*m.*ou hp:ob otzj7 o on9*-9 5n, ?

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 initial) i 7fcyr5cqw(ly uncompressed horizontal spring with wcify5 (q c)7rspring 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, slow ;4duzf;q vgr:lp ox,sk :f0u1(zrk)ss down her 2000 kg car to stop for a red light. Whatr 1;puqdozg:,(su)xv4s:fl k;0zrfk work 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 6b7.ak-w( xn b.7xyztp9,je ihqg jr490.0-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 beforjx. p(njxg9h7w-b 9e zyqt47kr i .ab,e 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 kis8u-w9. wk+r u iso8na ,(xqrhnetic energy. The friction force on it isrrk8(-.su wh9inau 8wso,x q+ 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 apnjpx 0)j5.(os1gp 4ujr :ja/ e2s fxfnspzl(/plied horizontally to a 2.0-kg mass on a level surface. The coefficient ojxu1 5a:pg2 z)( s4jje/pp(ls0 or js nf.nfx/f kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m h2d8c 0abv t(mmigh slope. If the work done by2b(t0da vmc 8m 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 pl f1 ptmr/a()uoane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the t f/tm ()upo1raop 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 rel-yra/zy z-8c-b sq ,pqeased from rest at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic zqa8ybz p-r, c-- /qysfriction 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 height of 10.0 m, and strikes the grounde12b(tsyt+l e with a velocity of 7.00 m/s. What average force o t+1lbse(t2 eyf 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 3k(tbrypicv582q 0. -n:vafzgzaw1 cusing energy when he runs up a flight of stairs 10.0-15byw-vg80f.zka c(pqircznv : 2at3m high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object wihcdc q.by1j5m n6zis7or + (;l3e4t x4ukgvx7 th a constant velocity of 5.0 m/s. What power must be delivered. qkx h56czjyugtlx74cbn(v1;3e ori + smd74 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 h+hplz+-d sg8k r? (1 hp = 74g-hsz+ 8 k+pdl6 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 ridiogf,/z puqoftus0,y; y u ( 93nco*c7rng. How much force does her foot push with when she is travel3 s0 ;o c9( fco7,tq,rpu*fznoy /ugyuing 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 7.0 s. What is the av3r/+kzpp5 h8n jgthh4erage power delivered hg/8hzp5n pt4hj+kr 3 by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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

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