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

1#

What is the correct unit of wor x .nf*p4 mig)uh7gwj.5op8s vk 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 ces ,upzbf5o xe1 j5us-7r+ezd :9)dvfs.t:z 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 s;d h m04rs0cwytationary brick wall, the amount of work you doc40hm rw0d ys;

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 beingrfn/ ul;03v)wr5et0o evi4 ge held there. How much work is being done in holding the box in thigreif o) v we34/ 5vnutre;00ls 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 f ,i lnj10ab;kn 99daatn6 4vhsorward at a constant velocity carrying a 10-N object, th4 s 9iad,tn0jhnl;b1vna6k a9e amount of work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then lt+ nlszd-/z .yv5ndpr.ac :5o *ak8 nreturned to its original position. If the total weight is 30 N, how much work was do lva nl8.5 5- rt ckzyza+./*n:ondpsdne?

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 actingg1cau s0ysx:8dmd 87f 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 work done by gravity l9s)dru o2,v ;l(p-l rca(yko while the ball goes up with the sigrlrl-u;ap(k,9dv o( c2o) s yln of the work done by gravity while it goes down.

A. Work is + on the way up and + on the way down.

B. Work is + on the way up and - on the way down.

C. Work is - on the way up and + on the way down.

D. Work is - on the way up and - on the way down.

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus psm6roq l.) k2d4z h:msosition (F vs. x) graph, representsmkr6sh l z2):om.qd4s

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 vsv t4t*1ajebr5. x), what represents the work done by t*145at tjrbve he force 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 ivaa4) uofswi29 7(u0exg; dibs positive, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an obje(a0-i-j jt iaq+ d+yztct is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zerlip+cu hsg :ug;* v+6so, 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 :cpdo l7o7qmdw(+ +px as much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energ7 dxop: m( d+poqc7+wly 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 hal0y:5 s.;afr q7s 1lpxcy+mzbbf the mass of car K. The kinzs71:yb5yq0sam p f. lbxr;c+etic energy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speed.7-i1dib( jdid 4- gyamo(1 vek What is the ratio of the final kinetic energy to the initial kinevkg i4 (iyo-md1b1-(i ej7 addtic 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 ll9bjzdyx..hdp c;n 624la3pa speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio azl;lj.92 cyxd4 .bh pn63pl dof 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 18xkkvxrf7vr c4 *)/nt.0-kg mass is moving with speed 4.0 m/x* cvkvx8 f)4rrkt7n/s. Both objects encounter the same constant braking force, and are brought 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 certh,fjl4cth +8jdsqu4 d)p)zq8ain distance on a straight, level road. If you had been travelqh) us44zdf)8pj q, d +tclhj8ing 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 an elliptical orbit. Negh 36btc7cj5ztlecting any friction effects, what happens c65z7ttc h b3jto 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-energby1h7xb5r(cw*h p b;* ppcxq/ y principle.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to hav encd)k65m3mzp5i )ie e negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from restx 3hvx)6q w/ye a height h above the ground. A second object withqxx / veh3wy)6 four times the mass of the 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 the end of a spring causes it to stretch 5.02+gr/q pz8p ugpx)k .t cm. If another 0.200-kg mass is added to the spring, the potential energy of the sprinzg+t82pg p )/ qpk.xrug 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 energ ksy6 zyr7na-8pb42f zy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to its potnt- ,si2/ p idl3r 5zzw2zhtq7ential enersltq z7 2p-hzz/i 3w ndi5rt,2gy U.

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 ow/k(hz5bp **gcrjweu3py :*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 velurm/vo 9.z72t8z/5 pfrns3ywh (tjqry heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictio. l 9rq5tf7zzh/s 8w/vujt(p my n3ro2nless 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 .1q pg,t m0gzfzysn2;$m_{1}$ 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 conservaliao/wsmr yv,93 )t; tk 4np)ktion of mechanical energy for conservative forces4kn)m/t p9 ;swkoriy)l vt,a3.

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 friction ukpu;c-t 1:lu,ao-bgis present), to the ground below. How does the kinetic energy (K) just before striking the ground compare --ock ,u gau;tu: pbl1to 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 kineti 8c*nk3il(vkq c energy. Do not ignore air resistance. How much gravitational potentialvl38(*qk k cni 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 potenx+ 1ohy d:2)cka1glpstial energy. Do not ignore air resistancegsycdpo k la 1h1x2+:). How much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservat.5noua;x+ t fhoo) mw6ion 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 is6 pb,nzeqfcyoc9s85 rvd +x 7(

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 po*q bwt17jzjd )wer 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 a u c:sze894gokqy( ;ddynit 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. Tol7u:r b 4-rbc4r)uhhy do so, your power output must have beenrcuybu)4h 4rh -b:r l7

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 are g3c*4pbl5c0d+m2ziy gs 4jt a constant 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 hexyjy3ms /4 v53,vl.z2oa o fvnld there. If the object weighs 90 N, how much work was donozoy3.3jf 2vxnams y5vlv,/ 4e 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 .l v-f6czokl(*ae 9kkbook up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of(*kok vlkl. fa-6ez9c 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 pu 2b2j11qe ixawlled upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 5500 N force?22ejw1qbi a x1

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 force of 5550wh/1px b- u 5zba;e5 cfgpzi00 N for a distance of 50.0 m. What is the work done by the weight o 5zp; b/e0pg-iac5zux1wh b5 ff 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 ppcjc r..0*bchulled upward with a constant force of 5500 N for a distance of 50.0 m. What is thr cc.h0p*j bc.e 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 6.07 y)h84izvufj 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 fruisjbotqbhw3z1 :hce47:u 2iy/ t slides 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 Sarah in a sled on an icy surface (assu 1;oz 2:hugl(p/0zof ggudb5tme no friction), with a force of 60.; tg2hod uzzfg:/lug5(0o bp10 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 t.y(2g:so8b. dtmqp+ gv m at8mhe force. The graph in Fig. 6-1 shows the force versus the objectm(8g+svmb :qd tgoma2.8 y.tp'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. rpoazbk/h l-q7s,;2w t xic 706-1 shows the force versus thxp qi -slaz/tob,2khrw0;7 c7e 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 j*1hjonvt9cl r; k( l8the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from1cj9o;l8h rj(*tvn lk 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;o m;nwg jth eqb3qsh xky5 5*t/iyv/8ajx66/ of the force. The graph in Fig. 6-1 shows the force versus the objecxisq;axtj*heq ty6 k5v38 j65 ymbhg/w/;/ont'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: gs 1 +fkj3drmz/mt987agxx g cart (initially at rest) across a 10 m level surface. What is the final kinetgzf8gk:1/ txm+r3jds x97 mgaic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initially at nuq:.6gl fvxcm4w4l0rest) across a 10 m level surface. What is the final speed qn ll:g uvxcw .f4m406of 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 muchb sxhs4:4 ye dwr7x/a5 work is required to stop yhds w4:/era xb sx475the mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance 8pj+,sn;av-dic glqq.7 rci0 is required to stop a car moving at 50 m/s under the same cog,i;c.l7 cdvq apjnqs 8 +-r0indition?

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 ga5 (ayl;5 i26k(x wdr htpdin53eb-ldun propels a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm.d n2d-(3hrk ( 5i 6idlp5alyb5xw;eat 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 gijo7r 0 l qunw1b190o80 N and a vertical component of 60 N. The force is applied to a box which rests on a level fricow grj1bq n1oul907 i0tionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, striking 4g vcnb (mupo-(-wyx i;*x t(fb2(qhw the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force ac4xcyi - vm*nh (( fpwbt;oxg-(qbwu(2ting 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 c3m z h8;rq./xuhi h(hotf93xof 7.00 m above a floor to a height of 13.0 m a;9z x(xh8c.h uhif 3rq 3mo/thbove 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 plane is 4 yv392lowqj/uis l6 6, b8fwxq.0 m long and rises 2.0 m. If the plaujq2/s x 6iq93wlbow,86yf vlne 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 the spring to stretch 2.09c 7vg xjtw3z)pzq;7 h tvb4+h cm. What is the st)vhc 9b zt x7 j34qwh;z7p+gvpring 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. H2xosv+yz. ly+zyj) x 6ow much potential energy+y jx)62loyy+zz .vx s does it store, when stretched by 1.0 cm?

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially 1mqmvy.apf 1m1a+3gnts 2s 5 cuncompressed spring with a spring c.3 tp2mac15q a nmyvsm+f 1s1gonstant 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 required to stretchmb3pt/ cpg ; fzr6kq+4 a spring of spring constant 40 N/m from x = 0.20 m to 0.25t f;zgqc3 /kbm 64rpp+ 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 N/m is initiallyoc qc e8hop5p9 u8f4z8 compressed by 3.0 cm. How much work is requ8o qpc zp8ceo45 8uhf9ired 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 re 0e h;bu03on4hkiph: mst from the top of a 50-m high slope. What is the speed of the slier 4h0u h3:e; pmiohk0n bon reaching the bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the )cu6;c ckn /ss2/b /jn5kzjpw top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m i /bcwc52;js kzn /nckps) 6/jun 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 bottom, it has (z5 g/)x.n delf*k*goc8 ixj ka speed of 9.80 m)x ef/ 5.*gk8xdnjzgk ocl(*i/s. What is the 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 flooeha rjkb;p5 v exejn )*kcfy5*) n,:d(n.r1dbr. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it moving?djekn*bkr fpa evxd h5*n;,ce.)bjr( :)yn51

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 6 c axnxv8b:8tup from ground level with a kinetic energy of 40 J. At the exact top of its tracnxb6x8a:vt8 jectory, 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 J. At theh-iadh(:xop- e03x t8v spm v* highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it ratpxh hx-epmi3(vs* -o vd:80 ise?

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 rer-d gtq/,e *.cyy+yldst at a point 45 m above the bottom of a dip (See Fig. 6+gd rt,qyly.*-ecd/y-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 sta3id4k 5h9io ybrts with a speed of 5.0 m/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 topbkyiih543d9 o of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of of*khw7fdzyt3rh :+q/a7q7qa 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, whic*zwffr +y:ha37 77 qk t/hdoqqh 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 spetq)u ux5. m:kqdm)u/hed 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 pendulum of length 50 cm is pulled 30 cm away from the vertical axis and relysp1k29u)f1wffo5le br q4c/eased from rest. What will be its sp cfu21fqby9elf5p/kr) o ws14eed 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 imp3qm,:qyv( xe4l nf xdw0/r )+6ehe4 ,b jkainitially uncompressed horizontal spring with s,qmqxpl+:ni 3aw b0e d44 veyhf(k6,e/mxr ) jpring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to stop for a red5)w,i-eensx )djv b 5y light. What work is done by the friction force againsv n,be5i-e)j)5y d wxst 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,slp wk 9b j8*man0(pu8yfzd: between a 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the objec:ulapm*wd8zs(0b9 f8p, nj ykt 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 surface. It has 24 J of kin03 mj:y7 t+mamt pt.u1 fmv6unetic energy. The friction force on it is a constant 0.50 N. How far will 3ut: .um 0a6p1+m jmnt7vymtfit 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 2233u f3w0vtmdq6tawg i:r z u-.0-kg mass on a level surface. The coefficient of kinetic friction between z u:ifd0awq 63wu-t rg2tv m33the 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 fromsg iw59) mj6wyrlcdg/7n9 y*p rest from the top of a 50-m high slope. If the work don6 ) y9*igyn cmr5/wgpl djs97we by friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The plane is 4.0 3pjpatba *x0.m long and rises 2.0 m. It requires 3200 J of work to get the box to the *p 3.atax0p bjtop 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 rb65 (8kf-oa5oefy 3zoir q9yiest at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the spf8 oazib3fro e6 9qy(ko5 y-i5eed 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 o8x5bxa p9i0( emwj(2waepkm7f 10.0 m, and strikes the ground with a velocity of 7.00 m/s. Wh7 b0 m 89iawjmwap5xx(ek( ep2at 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 energy when .8jhu 0.v8u-yfxmm l5jo.q aohe runs up a flight of stairs 10.0-m hum8.o0.o5axmjfy 8 jv u.-lqhigh, 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 tomih .wc433omove an object with a constant velocity of 5.0 m/s. What power om3o. wcht3i4must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp moto0 r2vpk1o w of81g*awyr that runs for 1.0 hr? (1 hp = 746 W) awv8* 21owkf1yp0org

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 6 7iv lju9n*yfp -msm:*ejh2mfoot push:fmpe7*hil yvusnm*j2j m9 6- 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.o0, gzyh*z /c rpje w6g*vur fzg:y1*.0 s. What is the average power delivered w: /f gh*01gc rpry*zz6j oe.*u,vygz by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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