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

1#

What is the correct uwzq,/ kt jts.wyd(0(onit of 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 a syste0 k6huewgzn 1;m 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 stationaryimexht-x2 g3b y3 44fz brick wall, the amount of work you dmezx 3i23xgt4bhyf4- o

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 jd m.e8,ci1cbv c;i:ais being held there. How much wor: .bc,;acmi 81djicev k is being 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 forward at a cons3 . kjqii1hzmz5 k5vdwkk1*0ze 81qistant velocity carrying a 10-N object, the amount of work youwk .se3kqvd 5*0kzi 1ii1q1m5z z8kh j 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 ll5 m9,tlji1xyifted vertically 3.0 m then returned to its original position. If the total weight is 30 N, how mi9ml1,xjyt 5l uch 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 objecvtsn +tb7j)ob kg zo5qr9355gn4t; jit?

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 o*a 0;tau-xvs- zr7 xiif the work done by gravity while the ball goes up with the sign of the work done by gravity whit-var; za-s i7xx0*u ile 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 vs. x)hj) ,/cnakl qeab.m;8 graph, representse ; a j,/bqc)m.lna8kh

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. x), what represents the work don/s.4 n;xar wbie by the forcxw4r/ bni;sa. e 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 positive, then the object's kinetigh.r jo ia6shc-w 7)hun40g 1kdi fi-:c 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, t 5gxl 10 xqs8kdh1ipc s1z6lfsz8t/m7hen 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 kinetic dni(.zi5; j(9 swkfhj/3 aumnenergy

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,vy4z01+ dc-ps)cenodooo1r4s4 i)n f and is moving at twice the speed of the car. Which statement is true about the t dnov4)p1fo-r o4+s ezi)nc4do1 c ys0ruck'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 c+6u :gw/ lrn hfnar9bmoww3)k8 9f9vqar K. The kine9+w 9nwk8buf ah)mg n qrvwr:3f69l/o tic 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 an h;j2y2zb 1auod bounces back with half of its original speed. What is the ratio of the final kinetihuz21;joyab 2c 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 a .*nih1g9n5dnryv3 jho1 bv- at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to th3 jd9nhavhr1g-b*ivn .5noy1e 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 movic d dzgd* bhml 3mzq717j0ilip0l/b; (ng with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater 0gjcbllmid 1i*qh md b/;l7z zd073(pdistance 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 spss d69+fdt . vvv(b)ckid a certain distance on a straight, level road. If you had been traveling twice as fa td9 (6vdf ps+scb)vv.st, 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 t kegb/ 1g 19giuhl8:vv,8ggk lhe Sun in an elliptical orbit. Neglecting any friction effects, what happengg lu ggi:ve91 h/k, lv818kgbs 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 -4 bh-54czn we36h kuhlwjq xcf 5:r4tprinciple.

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 negabjfw 4tlx,wb,0kd d ) nm8:)srtive 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 rpa.0qt t3 o7rfrom rest a height h above the ground. A second object with four times the mass of th. t03 7trorpaqe first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to thk,r .*p8io/hhffu6 the end of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of t*/to,6.f8k hhupfr hihe 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 sy/swbs v 5pvg evqz710+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 K, *z vy:37o+hiigimy/uto its potential energy U.ih +/z*uy:7vmyi o3gi

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 hillnqap4w ze57p5m2jd:t .

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 em6xpyf-t. -xzz8 n,y kqual speeds along a level frictionless surface. They both slide xty8nfk -zp -,y.mzx6up 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 apq,,dyez-th+5 0*d.nhl qpy$m_{1}$ 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 conservatiomdlmdd56 4-yon of mechanical energy for conservative forcesydld -4do6m5m .

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 kn;aj1nv n75yof a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potky51 jn7 v;annential 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 energz hatoem) )d*/y. Do not ignore air resistance. How much gravitational potential energhd*t / mzo))eay 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 3)ru)e,e 5 ;u.dw aikjq0 J of gravitational potential energy. Do not ignore air resistance. dwej);iq u e, k)au.r5How 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 consc32(s xomi7b- 2bdkf92huh j vvw i:/j. pm*fvervation 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 isj +yf**o bjl1u

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 exprkl dij 33b6zkl;yp0n u8 k1:ga8gbn;uessed 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 of pms* 1t+8r ; mux s0vdm9bsr*god*j x6xower?

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 wor d(+c-p-5xofpjjf q s(k in one-third the time. To do so, your power output mu-p ojcd(px(j+q 5s-ff st 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 cons)c5j 5t.1y wgm:whk-f7r lhwxtant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held th kywo 44; xyb2v6;eowhere. If the object weighs 90 N, how much work was bw h; vx; e4kwoy2o64ydone 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 constant 6.x*2e /iva a) 9jnpgbjzq rhb.9j2ouvelocitg.22).*oaa enq i r9/u6zxjpvbhjj9 by of 0.50 m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward p(i; 1j hr74,llw iahdwith a constant force of 5500 N for a distance of 50.0 m. What is the work l hlwdjh,(r7 14i;ia pdone 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 pih8/bkz1il8g 66 vbe vulled upward with a constant force of 5500 N for a distance of 50.ivbk1b g ei66/vh z88l0 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 pull 65yl m*vb54j-ff / jseryqe9ded upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work d6sb9fyjev d-55/qjf* ly er4 mone 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 vdsqas(372 qiu8a r1t gv.ke,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 j1is:eg-3fkb t 7wt1j.0 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 in a slek y(5ay8vqx z4d on an icy surface (assume no friction), ykqz4(y v5 8axwith a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the directoxqoc; .8(g8ktkfe9,dmgn 4x ion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Finx.g (tdn4,k ;x m8eogk oc8q9fd 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 dwzkfmot,h- ysi m174 e5y,/:twoy -evirection of the force. The graph in Fig. 6-1 shows the force versus t54wws /ve,mt -eh-,fmz1i yyy7too: khe object's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Th7yh6r 7 qwsx:ce graph in Fig. 6-1 shows the force versus the object's poshw6y: cx rq77sition. 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. Thev 7z7 ouw;p-nq graph in Fig. 6-1 shows the force versus the object's position. Find thew;-o7qvzpnu 7 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 (initially at rest8sj .fn(nfk v/) across a 10 m level surface. What is the f.n/nfskv 8j( 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 move1w+ 5 2(,elynlkm oynj a 55-kg cart (initially at rest) across a 10 m level surface. What is the final speed of th2n+1 ,nl eoyy kml5(jwe 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 fc zj-zg5)voumo1.g 7 w2i br2m/s. How much work is required to stop g-fbo z2)w5z1ivg 72.ujmoc r 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 car6x*a o)k 0 :1nf,9ymdcmomrul initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under tn6o:a k*,10d9ufymromx)m l che 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 force )j 4i,o)trk; emcl d)bof 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligmbd)t)l o 4ec;jir),kible 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 ver:pvdzl1*u. b. is hlj)htg9f 6qlk 0+wtical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart'skfz *+1ld :ljhq6bpiv)0wlg.u. t9sh 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 ;h1fh9zhau orq) 1mn-a bale of hay, striking the hay with a velocity of 60 m/rfh qzao n1hmu 9)h-;1s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved fr fyk)uq /kow,zo3 vvb 7)ip78wom a height of 7.00 m above a floor to a height of 13.0 m above theyw 7 8uz)p o)vk7vq/bi3fo,wk floor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m long *hg e7t0gxnrg-x;etij3 e3 95eunp4 oand rises 2.0 m.huirngt49p5e g03 3ex 7txne g-* ;ejo If the plane is frictionless, 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 then wz36 u uo utdt+3* ybe3ox(/bs:luy( spring to stretch 2.0 cm. What is the spriuotsoyy:( xnd*(u6u /+ebw3 zul3 bt3ng 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 z) em ao2x8w6ja spring constant of 60 N/m. How much potential energy does it store, when stretch w86o 2xea)jmzed 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 initialx k(* v/ky 7yb*eac5ktly uncompressed spring with a spring constant of k/ea7ykb*y* ctxvk(5 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 con6:g;le(uodiz7 (q* p6cnx fii stant 40 N/m from x = 0.20 m to 0.(66d7(i:lniepco; xqgi zf *u25 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 constant hb+p(.h*n 07j pc nnig+rgo wphi/s-6of 15 N/m is initially compressed by 3.0 cm. How much onbs gpwh0 p p+*n r/h h.nj+icg7i(6-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 ee *g57xira, na 50-m high slope. What is the speed of the skier ,i5e r7egn*x aon reaching the bottom of the slope? (neglect friction)

A. 22 m/s

B. 31 m/s

C. 38 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 ofh2ydm+9 u1kk uf the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dr9m +1ku2yu kdhopping 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 planxb cwo(xt:r ot8 5q8,re. At the bottom, it has a speed of 9.80 m/s. What is the vertical heigh:o(8b5tr c8oxwtr q,x t 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, y f, p*eaoe e3d.oui37 ic8.nuits potential energy exactly equals its kinetic energy. ,deae3ipeu.u *i.78c3f nyoo 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 fcm4a0ful0 q+i h0x :aN, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its traje0l+4a qmfuaic0:xf h0ctory, 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 energy of 220 +y )lx6c lfuojo97fh 3gz/6n zJ. At the highest poinx7jfn6yo9z3l z )hg /cu+6lfo t 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 from restt pf/ugszkp:bi7.kpcx28m21 at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect fricti7 g8zp1kf pb.:xt pcui/s22mkon, 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 rqn ,np.0* j-*vgv viam/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the to jv-rp0qn,a*.* i vgvnp 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 sta)igu3e lhmp39x5s 2fnrts at a point 30 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of tfxp3n 9hgu5s2l)i m3ehe 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 sp0 dw7.w8( fhnp)hcqp +nsyxf 0)(lhpn eed of 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 2-kg pendulum of length 50 cm is pulled 0 mcjnm(;:tvi7y zxih4 2(z;tz:0vfl y.24 m away from the vertical axis and relea(yl47z; :;izvhvfxc ty m(i: 0 jntmz2sed from rest. What will be its speed at the bottom of its swing?

A. 0.329 m/s

B. 0.877 m/s

C. 1.316 m/s

D. 1.097 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 uncomprqehg-j9wn b* 0q6xf8b essed horizontal spring with spring constant wgb 6 -nbjfqqxh*e08 9of $2.0 \times 10^6 \; N/m$. 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 2000alf si)z(d*-6 rj c8lz, ma60e;v wnvw kg car to stop for a red light. What work e ld w( fa)zl86 viwar6jv smzc;*,n0-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 object and kuorm y3-/i,x a horizontal surface is 50.0 N. If thekxmoy- ,3r/ iu initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level suje+; 2m/y 2iij1fk ulurface. It has 24 J of kinetic energy. The friction force on it is a constant y2k2jlif;u ij e1+um/ 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 mahs74gvfy c 7r ds cvk)l808+eass on a level surface. The coefficient ofgc 7s8d+vyreka70f)4vslc8h 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 res9i7 p)r yozf;f:mhz b7t from the top of a 50-m high slope. If the work done by frizfri 7b;9mzh o7f)py:ction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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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 ap8r+xc tu68jv 5ljvk9n inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction fojrl8 x8jv6+pukt9 v5crce 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 9 +b5xcahup2wbrd ku-*oa-.geased from rest at the top of a plane inclined at 20e above horizontagdr2ph .u -b+* uk9aw 5abcox-l. 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 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 heig25sd x,h r.qs nu 5z,fqm3f4kzht of 10.0 m, and strikes the ground with a velo.x4z s53sf nr,mkqz5d,fu2 hqcity of 7.00 m/s. 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 boy using ene2t ewfs zl +n +hp)jqa6bs3/-brgy when he runs up a flight of stairs 10.0-m qawb sfe6 s+3)pnl-hbt+/j2zhigh, 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 e)-spgv(vkqe k;ok-* move an object with a constant velocity of 5.0 m/s. What power must be delivered to the object by oq;g)*- k -e (kvkvsepthe 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 ,i sf/egx,*riused by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 7, ,s f/eriigx*46 W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. How much force does her wkl5hf320 r xvkpk65to8:e y wfoot push with when she t8wo6ve : 3 k0hfpy5rkwk5lx2is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is the averageu cion smbz1+7gn24h3 power dg2m 7uh1zi4+bo nncs3elivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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