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

1#

What is the correct unit of work expressed in SI units?qr u1e-jg., sob,1ywtg5ri ;8zh eyd*

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 systemu3n hia- u:kd4 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 againstk3-imc.u/ akorhg2sz +b* ex 2 a stationary brick wall, the amount of work you dgm k.-ox*zu2kshb 3c e/a2 i+ro

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 being8toc,on-30f1s lj a sx ;dgp,j held there. How much work is being done in holding the box in thistpj,l1-s xd;,gf3a so0o 8 jnc 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 forwazq a 2 m7hd ,x3:*,g z6kz3 7wujldulh:bjt9tlrd at a constant velocity carrying a 10-N object, the amount of3hz,jbll6 3zthu,q* w 9::ka2dgd tj lz77x mu 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 returned to its original ),ggjc mowcdu:n .)w 7position. If the total weight is 30 N, how much wj)cwmd .:), gwun7cgoork 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 objewprxbb seat/qkm- umiw/ 1;b+5t5q)*ct 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 straigh dewoq4 29vv2xt up. Compare the sign of the work done by gravity while the ball goes up with the sign of292vev dxwq4 o 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, p;z,u d*/k u0r 9tqthkon a Force versus position (F vs. x) graph, representsr td qk*/u;90u,hk ptz

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 qidj127z pan* position (F vs. x), what represents the work done by the force F?1a*jp ndiz27 q

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, thenu v/:gvr5n:x l 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 elcp;o ;efref-24 wh/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 f g,f h (x/fpnq+6gy1 srx9m1tobject is zero, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twice the speed okl0l6 vib+87i-pv+ ccoa 2wo wf the car. Which statement is true about the truck's k6co l+c+vlwi0wv a87bik2 p-o inetic 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 tm*gh7,g ;qgui1 fhvu5i: mk6ihe mass of car K. The kinetic energy of car Jk; iv i:m6g m*5h1ugqu,fghi7, 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 in nst56x4-2ujwca6 9 flad6r of its original speed. What is the ratio of the final kinetic energy tf4txnl n966rsi ua-w5c ad6j2 o 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 pebblq2jf2c m7 y pb/hb+(f(.y dnize is moving at a speed of 5 m/s. If both objects have p.y bfqd+2c(nz27f(b/iymj h 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 kn3tiwj5t4.2 j;bj;egigm, e speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the great3 4;gt ei;mnibk jjt,.5e gj2wer 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 pan7 y*ca en* ;l,b oohj5fc5mfz+hfv3d,ic, and skid a certain distance on a straight, l f+c*5h 5doa *f j,lbfhzc3mev,yn ;o7evel 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 the Sun in jucfgwi ,d gu3/vy9kt2 qj***an elliptical orbit. Neglecting any friction effect 3 jk2wgv,*ju*dq/g iy*9c ufts, 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 prfc2pt)v9g xue ;pu7; nnhvtu9k/6wz0inciple.

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 s2s8 paoy5c+smz 6x8nncq l, 8rystem 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 fugfv+woqe)(f(t f1h l:t4ah2)t0oii rom rest a height h 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 object compared to the f4 2)i+wtlf(v)ohteu aq1f(:0g f ho itirst 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 s nfy3t) t48y8ja/j ern k:xk7po s4pn4tretch 5.0 cm. If anothe)ajpj4nf3 p t4:ks4 7k/88xyoterny n r 0.200-kg 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 systemearen9(ywfhxh1,5 e 5i3 /*nv 4tuoq d

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 treae/p 8l;;.opanv q)x be. Compare its kinetic energy K, to its potential energy U q ep;o8nxaa/lp) vb.;.

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 sxgat5w 4 .ftm6n: rmgh13j7phill.

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 slidipuasp5o- :lc,ng with equal speeds along a level frictionless surface. They bothp lc:opus -a,5 slide up the same frictionless hill. Which rises to a greater height?

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

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses nt8 mo.cjhcg ovl4g4; / 3a9yi9)ow pj$m_{1}$ 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 conse xv6mjewyk8 94rvation of mechanical energy for conservative forces.6e jm84vx9wy k

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 air7*6bt fk 9vjq yqib-xf8wx97j (air friction is present), to the ground below. How does the kinetic energq6i* v7b wk xbtyfj799x8 j-fqy (K) just before 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 gains 30 J of k uuwqvr3 gkv*lbh*-2n; o yut*r/g1- winetic energy. Do not ignore air resistance. How much gravitational potential ener*-n /rkvg 3;w*tgoq u*wlur21hv by-ugy 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 potdye*vhmpq 193ential energy. Do not ignore air resistance. How much kinetic yv mhp*e39q1d energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation of enerci mr312xr-s : cl8zxv15nqba dil *r*gy.

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 isc b8md(cx )uu83 h *89ey-dnkh ccevz*

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 unitwh- t*-ofcab)hiq2.pub1 n-w of power expressed in SI units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not naq0 3pbe:v, 0cxxxfg.s9bx 5 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 work in one-third the time. To do ay5q fm-a kbe:s1/ ;)ihc mw4aso, your po -4s ;mfy a ekb/wmc1q5hiaa:)wer 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 cgws., / whan0uar'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 p:5 ,)hnfqso5ngdz.l 0mf;cqand held there. If the object weighs 90 N, how much work was don s.,nfndlm5o czh0 ;qqg 5fp:)e 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 ,2wvrya aug72hq.nfzt ;8 avqixn33 3el70nsthe air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the 7r38ga x3,evz w il3h2v0auq2fqa7n n.nt;sy 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 with a constant force of 5500 N for a distaidgst2v +h(3q nce of 50.0 m. vdi+t q (2hs3gWhat is the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a conse7ivqdag n/,dg a5;223 l3bwlx4kbuxtant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of the elevav3ll ; ,e57wx /iqd3 ngkgbxdbu4 a22ator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N flkkx:0 2)gup1g7jl e*mqr+x mor a distance of 50.0 m. What is the net work done onelu2lq *7k:g+r m j0)1kpgxxm 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 )(na2( p4z9h exdd n7;yjzbpaalong 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 d/cdxemaf:i, xp w b-8mp7 ,e+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 in41 y dgx vx*4(p,uhws5 pjnoe8 a sled on an icy surface (assume no friction), with a force of 60.d, 5x*p4syp nv8o1 xewhg4 uj(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 dirrz:im j 1,fqa5e:eq) nection of the force. The graph in Fig. 6-1 shows thjmqz, n5i:f1:q)eaer e force versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig. 6-1a gkpq 5;j19kc (j1wvhn;( pab shows the force versus the on; 5ak 11kpgbv((;hjwc9pj qabject'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 directi0iz96gq 0d jbron of the force. The graph in Fig. 6-1 shows the force versus the object's poqd0r690zij g bsition. 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. ut1w+4 dfka rq0t y27lThe graph in Fig. 6-1 shows the force versus the object's position. Fiqyw24ut t7fr1kd 0al+ nd the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to moib-f* oz6c7kq ve a 55-kg cart (initially at rest) across a 10 m level surface. What is the final kinetic 7 oz6f*kcqi-benergy 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 (initially at resxe 2 yq3b2qh-x kht56td;9m nwt) across a 10 m level surface. What is the final speed t2dmw5exn yx 29bt3qhk qh-;6 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 isvhkmg2 n 6jze,a*4me ( required to stop the ma,e*genkzvm 6 ma2 4(hjss?

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 stovcpu u3*3:4biq+xj ty*9r ijkw5ife*p a car initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/qi4b*9cfkj r:j*w+tx5 vi3ie3u* pyu 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. I:a3j)8i;9ay ji 2sy+a tokezlt is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligib+lst3; a9k:ie)iay j oaz8jy2le 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 compone kv xh1z:9xuj9nt 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 cartu1x:z9 vkh x9j'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 horiz4iz 0kj5t*z.tj rol (montally into a 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 average stolki( 4tt*mrzj5 j.0zopping 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 4 me 2p)x+ao2kr2+ mnizoc2bfa height of 7.00 m above a floor to a height of 13.0 m above ioe4bn zfp c)rx+22mm2a o+k2 the floor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The , k z0ii7dlwp j(7b7m j69rtxnxfa;*jplane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done by the pusmjkpnj76(ibxrjf79*t xi zda7;,0 l wh?

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 d,)w3r/, vaugb6 n,s2kplcv imfy 18ostretch 2.0 cm. What is the spring constantdv as6ignp f/,yw ok3v )8c,bl1mu2,r ?

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 sp-kak au3cc n8hp9vw3,ring constant of 60 N/m. How much potential energy does it store,n- a3k389aukc pw,h vc 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 cn 3h7-pzz6za5d jai d7ompress an initially uncompressed spring with a spring constant of 25 N -5zjdh 76a3 idpzz7an/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 sprintuj(b,nd 44zg xh4uf3e 2 -hgyg constant 40 N/m from x = 0.20 m tgt4(u 4 uyz ej4dfn-2h ,bh3xgo 0.25 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 of 15 N7 pa,c*s1wv kk;n)v lf/m is initially compressed by 3.0 cm. How much work is required t v*7,a);vnp wksfck1l o 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. Whi-:isa3 xv p6dn)-ryr:d di)cat is the speed of the slier on reaching the bottom of the a6 i3-y:v)dcd) d-i psrnxri :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 with an initial speed of 4.mcitzi2g,t 3 c5q6g.r0 m/s. Nemz6r3 ti.gic5 g,q2ctglecting 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 plane. A:d jd6/2gaud;s cuq ) of+iqq3t the bottom, it has a speed of 9.80 m/s. What is thuqdquoi d :a3fc) j2+dg ;/sq6e 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 aa/h; 6isps*m kbove the floor, its potential energy exactly equals its kinetic energy. How fast is it movingasp*mh i k/;6s?

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*.x s666ukaj t,sbm.u-1 bqigs aja:j 10 N, blasts straight up from ground level with a kinetic energy6 ta6 :bak,i6sujgmuqsj .abs 1jx.*- 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 leaves the ground q2lpb7k(0 ntatfk4n /with a kinetic energy of 220 J. At the highest point i b74t0 nla 2kfn(t/qpkn 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 re3mj .fhw 31mjnst at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slf3j 3n1m .hwjmope, 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 startsb70dzj6.osp -vb iw5 6ibz4t dnwvd *0 with a speed of 5.0 m/s at a point 45 m above the bottom of a dip (Se p4dbvjdivds5*z0n 7i.wo0-z 6 w6tbbe Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the 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 bott h/4 /pc .ulu f5wx5xx/.ijzdvom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed ou/jz 4l5hvc. .x/pi x5wdxf/ uf 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 balloune p7 p)q/6n at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is puz wxy3 1o7kaf1x4d(vxlled 30 cm away from the vertical axis and released from rest. What will be its speed at the bottom of its sy(7z41xxa3f k o dxv1wwing?

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 hi+ncqkbes 13lxs,;46i+ayjlh37 o eqq ts an initially uncompressed horizontal spring with spring constant o +qqk a 4eynib;73+lc31hx jo,sseq6 lf $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to c mie 1k9rxj7a2wt359t0qfo vstop for a red light. What work is done by the friction force again v21wi5jc9qe0 m9ftokt7 r3axst 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 betweehl/ivnk8/u vv2 1dx9cfj7j6 en a 60.0-kg object and a horizontal surface is 50.0 Nh cj167j /v/v kxil u8efv2d9n. If the 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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教师可以抽题组卷或一键复制本试卷，布置为在线考试或在线作业，全自动判分成绩一键排序导出，省时省力

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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 mo r6ar/b/b2a, kcyarq;leu 1 4g8ki 9auving on a rough, level surface. It has 24 J of kinetic energy. The fri;igkey 2 1ra6ka8alr9au r/, /q4cbb uction force on it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level surface. p/-+a ll a8.yuvorg(z The coefficient of kinetic friction betweuo/v(la ylz -+a rg.p8en 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 ,/rvsn*f9 tkdc41 tnoc 17jbffrom the top of a 50-m high slope. If the work done by frinj*ct,fb71k 1dt 4r /9 cnvosfction 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 plane9op.h3svyi rd*mlcma9 *.q.i. The plane is 4.0 m long and rises 2.0 m. It requi3iv.a.mc99mh p* o.y*qd rsilres 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rec 1x0y 7b,yz89 sqic,ljb2hajst at the top of a plane inclined at 20e above horizontal.a b c7s,hcl9y bx0i2z8j,yq1j 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 height of 10.0 m, and strikes the :n4a.uhm7fqt 7yu ip0 ground with a velocity of 7.00 m/s. What average force of air f7iphafy.u4t7mq u0 n:riction 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.se jp:y8r9gl9qi 103tb by -cz0-kg boy using energy when he runs up a flight of stairs 10.0-m high, iisbcty y81:-ge3bq 9l rp9 j0zn
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a co ba*xd ;p2*psxnstant velocity of 5.0 m/s. What power must be delivered to the object by the* 2s;pdx*b xap 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 pacc(*txi: b ,are used by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 746 b ,(at*i cp:cxW)

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 j9psb x2o obe:qd 65 4oscrusdwn8h. w3;tz, 7the rate of 500 W while riding. How much force does her foow6 d2w 9 : bdop,oc. jh 75utonzqr34;xbsse8st push with when she is 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 1 v,.f4qccsl;vca 9uq average power delivered by the engine? afqlsc;cv14. qv9,cu (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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