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

1#

What is the correct unit sd:ek blhl50.obxv7e:a p +e 8of 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 system id +d4ulnb55vnj; f *x2rrt.hp f 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 yarjt4 .ao ;*ktou d4kta* oa.rjt;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 lifte1a)1 ln1rn-cikp ej.b3 uw:aad 2.0 m vertically and is being held there. How much work is being done in holdin)p-l1n.j eabai3k r 1c1wna:u g 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 c+pcag.f *p 9hen1i1s konstant velocity carrying a 10-N object, the amount of work 1n a k*pf ph9+.c1isegyou 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 1ptn)zsu, uk 6vertically 3.0 m then returned to its original position. If the total weight is 30 N, how much works )t1pzkun 6,u 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 v :m oi z7x5: :d8*znrmfwg,cbforce acting on an object do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign of the workyi* tf9g4 r-*mi 8tkpk done by gravity while the ball goes up with the sign of the work done by gravity while it goes do4k*k t9yii t8mp-*rgfwn.

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) gz.1p, xa*jcsoraph, representso1 * jpc,s.azx

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),h/ xpf pna/kt kfqf .)g5fw1mi7 s7y1/v*jil/ what represents the work done by the forcm7nak f p/y71 q5pff kfv 1i/l./x*wh) i/jgtse 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'sa,7:onyoy0gl3 5lg9qtoj* r z 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 isry)qs ggzu *;0 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 6 0 /qive 9ftesgos84nthe 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 mob,bgdf zi6s5w8h 9( nuch as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of thwf bn5b 8i,(96hdzgose 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 ca4 uw/jb twt)j481 kmjar J has half the mass of car K. The kinetic energy of car J, compared to ca/bjj 4uwwt1j)tak84 mr K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original spebt n1y9;ic 1ftefnnxh1h .7.ho+j 4yi ed. What is the ratio of the final kinetic energy to the inithh+f nb.;h4e1i c yn 1tn.o iyf97t1xjial 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 aq.tg3k1 lleyy64 ol,s gso a) we:c2p6 speed of 5 m/s. If both objects havggo6l y2lkaeso. )13ply:e6 sq ,w4cte 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 is9 tm*u) bkparfs /4y/y moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are broughpu4/rf sb9y *tmyk)a/t to rest. 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 brakes of your car in a panic, and skid a certain dic-iwsy*lrb jt *v+1 n1stance on a straight, level road. If you had been traveling twice as fast, what distance would the car h+vtb i1wc1s nyj*-l* rave skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elliptical orbit. Neglectink5ar05bxfy)p g 3**y -jwrtzcg any friction effects, what happenf3b)-pw jx y 05r*rgzaytc5 k*s 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 princ.ez( fhb 7hr0hz83 todiple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential energld0am l75jv s4y?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the grounj7zi -kmg3*n5eakc h2l2lz6 pd. A second object with four times the mass of the first if released from the same mneizl* 2c6j-5azk3k27hl p gheight. 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 the end of a spring causes it to stretch 5.v karj6u -ft;x:q,d 5er+/2zlm e +ryt0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring will e yqzm-krrj ,r 6ut/evlt 5;f+2:xda +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 syst ne3hu)uef k6t e07rp:em

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 ener :u*30cbzgzbv+bje c. gy K, to its potential energy U.z b.g+ 0bcczb:*vuej 3

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 drivin 6m8-dmux)i+reaar2 a g up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a.oa * *(z)kf+bchpea z very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up t*(f p.k*za)aehc z +obhe 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 n wq04t hh*d;7,tpf9eh2nyrp$m_{1}$ 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 : v-b0lpfu: 7rvmpz e5conservation of mechanical energy for conservative forcesbp ume p:l5 :0fzv-v7r.

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, through the air (air frictiz.9 0qg;x+wct;goqlz ; sean2 on is present), to the ground below. How does the kinetic energy (K) just before striking the ground coz. zwgcosetlg nx+ q0;2;a9;qmpare 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 rth:o1 y/kf;nniu*/ u,iujdr0d) f +vJ of kinetic energy. Do not ignore air resistance. Hd +tnf)uuf0/krr :1,inih/ d; *vuojyow much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational potential0 q oowwft( hqd6o+rj30 jj:r6 energy. Do not ignore air resistance. How much kinetic energy didodqj6(0ofo+q3 6 j0rtw: jwh r 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 enk7 bcfszx((u e*ykm6 ;lia e*s- wc-oqn)o 0d)ergy.

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 is3i4xm/ emskdo, w2zj5 bs.:ej

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 unitmg+w52 kc6 ve/t xolg7 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 isfx j,c zqg1*+2jzr u3t w(je,j not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-thi9k) x )mu(pp urp,7mwq3 hlw0ord the time. To do so, your power output must havep x9w 7mlqm0 )pru, (kpw3ou)h 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 accelera2l-tc( 5naga hzjoygc+ :lae0u(-6n ytion, 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 ver .yc qffq1u*:ftically 2.0 m and held there. If the object weighs 90 N, how mfq yqc.ff:1*uuch work was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book (2w3il3a+46jg ( yc yrkqnwfxup in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of ( (nayrkjf6x24wli3c+ 3qgw ythe 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)d -hu .zgbg.y constant force of 5500 N for a distance of 50.0 m. What is bhdguzgy-).. 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 constant rkgjxlll:zpr o1*0uy+5: us 3 force of 5500 N for a distance of 50.js*l y:x z0+u 3:ll5r up1gkro0 m. What is the work done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constank:/ga g:xu. iht force of 5500 N for a distance of 50.0 m. What is t:/xk aghgi. :uhe 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 aixz--/ bhatzu)h p159lndam0 long 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 slhl8 06pc zyh w)xmris/tc71fei9go )9ides 8.0 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 Soxzv x v*zy-:m(6xm3xacs ;h:arah in a sled on an icy surface (assume no friction), with a force * :mzxvx :o;cz3vm xs ayh(x-6of 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 direction of the force. The graph in Fig. q.5iyr(fdq 7t 6-1 shows the force versus the object's positi .f7i5dr(qq tyon. 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 q7 wrvceqiw j6/6/ +tzof the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the wc6w7rz eq/i 6/tw j+qvork 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 ( 3 wzqd4+crl:jff4i hthe direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done whwf3: 4+rcizf( j qhd4len 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. h:n.mg7 ,w5ve(dy glesla6df9z ls bq2y87/ e The graph in Fig. 6-1 shows the force v7le .glab6fes y d9 q(e/g,dlh7v:m5 zywns28 ersus the object's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at re zxpxwoa(45sn11ucsb0uzp 5; st) across a 10 m levc p x5ab;xz nu5041po1uzsws( el surface. What is the final kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to mor+*9l9 bl6p hz)mxz oive a 55-kg cart (initially at rest) across a 10 m level surface. What is tz6bo99+z mrl *xhi)lphe final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much work is reqkc mo/g,cg,p .uired to stop the mamg,cop, g/k.css?

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 monu2t)l8m 7,v )napkxiving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the p ,ivm)n)l8txkau7n2same 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 uo).cku)9osf force of 20 N over a dis.c9u ))so uofktance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a vertical componen: xn(9yz gx+fh od89wmsd0g*t9 bpq5et of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and xgpbd+ q dt9:50 m*gyh9xsw9nf8zoe( moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay,;:ffmk . upz6ld,esa ; striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acase; ;f6 :z.kufpml ,dting 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 fl64tv6c5yqp;ufdtr1rt /u, - biu wq q0oor to a height of 13.0 m above the floor. What is the change in gravitational potential en-4qyutc6 itw, u;rt 0pv6 5qb r1qud/fergy?

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 planezth kve;1) nx0 :or)cd is 4.0 m long and rises 2.0 m. If the plane is fri ;kvno c :xrzh)01t)dectionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to str1) 34voyjepkc9rz 4anetch 2.0 cm. What is t ner4ykc1vpoz3a) 9 j4he spring constant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much potential enqjk(hsuu(0.h-/bn icergy does it store, when stretched by 1 unbkj(quhsci-.h /(0 .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 anmt0vd 0y mw d6g6*c9ma initially uncompressed spring with a spring cons0m09d ta*mcwvdym 6g6tant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is require+g rn4c (mote(-zkt )fd to stretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m?-cremko(gt)( zf t n+4 (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 N/m kt (hd8bj,xghd2,q;8qhzjq: h,nh9o is initially compressed by 3.0 cm. How much work is redz,nb,tq 8 g(9hqjj8 k,dhhxh2;:hoqquired 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 :o3 9 bvpo iyn/bd8pf t3h2 :q7arzyp750-m high slope. What is the speed of the slier on reaching the b 7 yn8aph2: qbpd9otvyo ibpz33/7fr:ottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an,nrhr1ui4 vl57 0y9t vwcze7i kxkg-, initial speed of 4.0 m/s. Neglecting friction, hgr7tw klkyvc 970iz4 u 1 hvixe-5nr,,ow 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. At the bottgs)s2mw5zue+o4 b5 noom, it has a speed of 9.80 m/s. What is the vertical 5owmss e)u+2g4 obn5zheight 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 itvqw(j4ps c6 fnnb ,9t:w30 rxt is 0.70 m above the floor, its potential ener3nb6, wfw9:0c x(r jqnpt v4stgy 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 level wiw577gj -zrnlb* xz8uh7 b5xp z3tata2 th a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J u8 *2gtt a5jxn37-bp 7r whzzalzx75b. 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 le;gmc, nh 0*u;hydgq3xn. 7ukyaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launchyhh;c;3 y7gquu xnk.n,d*m0 g 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 rest at a point 45 m 0h6sb 6 .uoqj,5vecntvuen 5; above the bottom of a dip (See Fivn;e,6ue bq5hsj6c.0n5 votu g. 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. 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 spezuo q//5(ho il8p(dm9*)e) e ync faihed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction,)/z/ yhi( dceoiu) mf e aqp5o8h9(*nl 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 abovsccf/q7)fv0zx 1izcf xf4i7fq7+ 0qd e 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 bcfs+ 07)7fq4xzi fdvxqiq fc z0c/ f71ottom 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 z9gaq6 1 lfm8rthe ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pullefe2-pmbabc s6 ce.r 0 o+g8g:ad 30 cm away from the vertical axis and released fm recbb+6 af8.:0- aegos2p gcrom rest. What will be its speed at the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed horizontq5n(v+5cvvi4 *luj pd dheg*3al spring with spring constanu*5idqvj lped3(g *+ch54vnvt 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 ayvx/q2pi l b* jyhr+;;t 22 m/s, slows down her 2000 kg car to stop for a red light. What work is done by the friction force against tqp2 ;*blvyi/rj;+h xyhe 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 a horurzt6 )gdutf.s ))tvu.x,o/x izontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance wi u g6 v.t/,tuusxt.x) z)rdfo)ll 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, levbi5 ij51j+ednel surface. It has 24 J of kinetic energy. The friction force on it is a constant enbi1 djj5i+50.50 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. wz5b-6 vd s mqcwydb9m3 d02pz8 njh95The coeffi0vchm8629p5zdbn3-zys 5bd 9dww mq jcient of 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 t8*ts3/qmi7 zac e:zmc he top of a 50-m high slope. If the work done by frictio8*m zca7c:i/3 e szmqtn 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 u+j 4uz/ht)myap an 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 frictm+ /u)a4zjty hion force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane incli5zg-m: qulh/sl s l*spyd5*i1ned at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. W*zgmy s5dl p /*:li huls-1q5shat 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, andmiu2v7dupi-0 3f vx9 *ql pe)w strikes the ground with a velocity of 7.00 m/s. What average force of air friction vl3div up 9pf0q uxi- 2we7m*)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 energy when he runs up a flight of stal7 0b5xa8yd-xoq/ zv ct 7xr,iirs 10.0-m hic7iz7ql vox5-b0d ray/txx8, gh, 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 with a constant velocity of 5.0q 2sfis l:j:8 es57gt7y(ead r m/s. What power must be yrlgsd8s77 f2(e5ei:a : sj tqdelivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs for 1.0 hr? 3iw89o647n21 ujwzqsgedcbai 7ja k8 (1 hp 7id zjk9g1i3j ewq288acoa4bu76 wsn= 746 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 muchf.hmw/ado k4e.w un ,: force does her foot push with when she is traveli k./, o m4wnwfd:.haeung 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 average poweeku 5,7u8toz )0gu -r-u*zav r: 6 evncg7hkjer delivered e,kva*ju z- v -g uegzu6 rouc85e 7)0k7:nhrtby the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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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