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

1#

What is the correct unit ob((7gebj 12q.oga6d s0 hl s92mgpbvcf 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 aogh,z my jc51, system 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 stationar6p;z4 : ggs fzjb//8f1zwr vrsy brick wall, the amount of work you do/vf4/8:g s rbzz1rzp6w; fj sg

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 verticaj .q1:*)ewf wny enom+lly and is being held there. How much work is being done in hoy: 1e)w jfm*nen q+.owlding 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 horizontb -,vf;gm pgr l0;+qz0evqpe*ally forward at a constant velocity carrying a 10-N object, the amount of work vp zbf 0mq-p*levg;; gre+q0,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 verticallt-603hdn5ic ;ge91zp du ies/ 0ipub7ynmwo/y 3.0 m then returned to its original position. If the total weight is 30 N, hot;sn id b6n0iuuc3 hp95-0/o/ y71izegp mdw ew much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the object4osq:9e zzjh l.sk+8 e?

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. Comparzkpn/i 7fy, y1e the sign of the work done by gravity while ni, yp7fz1/yk the ball goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) graph, repr/ zfnh/ -x-tdo7ed9xvesentsf9nxt-v ho7/dzedx/-

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what repfzk)+1k3vuy w resents the work done by thy3uzkw1 f kv+)e 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 is positive, then b(q . q4s/t.o9z c zaogq9kv5ethe 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 e+ ;zn8 -x-tmi2dabar is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the object's kinetice*m0vd 4b pkv4 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 o(kt; txcaucb. n.+x2car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy comcx . 2un;b(taxo kc.t+pared 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 t0zp9d;l ls)iu58 q x7lwmsvbs2e c7h /he mass of car K. The kinetic energy ofe;v s/925u 8xl7z)dspicswl0hl mqb7 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 asb 9tukf(ql*c 1bt(2*yr5rz9b1 vpo e nd bounces back with half of its original speed. What is the ratio of the final kinetic energy frtbvb(*qop 51(teks c 9blz2 u*ry91to the initial kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed of 5 ge(xpn8,h 2f5 cue+df m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rof (cg5xenu dp+8efh2 ,ck's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is movingggan) 1o ;-vci with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distan) nagc v;1i-ogce 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 pangrcx.r) fxs;8c99 z wfic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the ca gfscw 9.c)9xxfr;8zr r 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. Neglectg hqev) 0h94nging any friction effects, what happens to t4v9 h gqheg0)nhe 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 )0ovki-jrc p 0q 22irxmk:nn-gu-s ,cprinciple.

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 potenk ryt57j /g0zetial energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. A second obje4xl 4y*q mx2(khjh*)h3zm r yzct with four times the mass of the first if released y(*y zhrm)34lx*mx4qhhjz k 2from 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 en zw6q7 cch(g6ed of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added toe7c6q cg6wz (h 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 e1bstyrl .z p fl6a9*6mnergy 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 Knb txed hf99l/8 -vo(j, to its potential energy U.99hv8 l oxn/tdejb-(f

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 up75bd8m p6 ejwf 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 very heavy object are sliding with equal v;+vm3fw8zlq.1a c9tfb j c:yspeeds along a level frictionless svlzb;yf: w3a19jt m fq c.v+8curface. They both 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 5obg+ khzj wo8bm5jl/ h iu13;$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical energywx6 qzv:rnmqc*r7 ,3 o for conservative forces. v*q nmqczor:3x ,67rw

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 is presenqm1 x 50 dpvzf;0bu6qyt), to the ground below. How does the kinetic energy (K) just before striking the ground compare to 5y 0qvmdb 0puz16;x qfthe 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 gaq8gu 7+c pk;kdins 30 J of kinetic energy. Do not ignore air resistance. kqgd 8u;k+pc 7 How 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 lnz*gj s03r,o poses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gaign o r,0jpz3*sn?

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 t*k u( (mdxy2cfru(( yqw5/xfof 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 is u2p)sjz+-4 sqz 3iisj

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 5b fu0: s;*:m*ld1rmcz cg bupunit 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 a unit of powe0aduzj2 hf ; g,q5)upbr?

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 2 sryg vs mqf/xut76* / j8t90d9jkfrhdid 3 times the work in one-third the time. To do so, yog*7 8ytr9fh qjtk2ju6/mxf v9 sdr0/sur power output must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleratiofj*e9 7mz:dzjn, 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 vertica4j vdqp,/0t x--da3:e tyetq ally 2.0 m and held there. If the object weighs 90 N, how mu0-e /q,edat 4-pj:axvty3d tqch 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 up in the air a distance of 1.0 m, attfq/x7iuu 3 8x a constant velocity of 0.50iu/ t fu7x3x8q m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pullenw 0mv 4b) /swje0qwe0d upward with a constant force of 5500 N for a distance of 50.0 m. What is the work dwje0wesvqb4 0w/ n )0mone 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 consta ocd4 j8k4rzvfno1f3) :rxd6snt force of 5500 N for a distance of 50.0 m. What is the work done by t3:ksn1) f6oorr8 dxfd4jc4vzhe 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 constant force of 5500 N for a distanckn1w t7u3q by2e of 50.0 m. What iswkuty 72qn1b3 the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up 6rt2u yq+ jcu2along 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 slsoppen3 g: f: zvi1o ff2u;ad,29,f-s qbo/ phides 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 jm*+w*ezad26mda dr( x wdz2, a sled on an icy surface (assume no friction), dre dawzm2zjd +2m ,(wa**6dxwith a force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of kbyn )+cl6 j2;ko p*ermlrk53 the force. The graph in Fig. 6-1 shows the force versus3ke2b +kkm5lr l; prc )j*oy6n 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 t1,gr1;gy tsmof the force. The graph in Fig. 6-1 shows the force versg y1t,s1grtm ;us the 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 ( r)u;plrpn2w.hm i fhu0z-s4the direction of the force. The graph in Fig. 6-1 shows the force versus the ob2 fhu.) n4izuhlmp0p(rr;w s- ject's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direcgb. 8u+fct)2-aut ux-jl+ cjd7d9ei gtion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the wdjd cicjgbtu9lt.8 a)uxeu + --gf7+2ork 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 cap3eo,gxv t 7-trt (initially at rest) across a 10 m level surface. What is the final kinetic energy eto vg,xp3 7-tof 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 3y66jwon- xe ya 55-kg cart (initially at rest) across a 10 m level surface. What isye3j6 y6ow-x n the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much work is requflz7 ,j. qv,,drk,t ufired to stop the7,t, k zuqrjf f,vl.,d 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, fu wxyh2k92+r what distance is required to stop a car mk9y2f+ 2wrhxu oving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun przb)0n 8*vko3x5e98dxsr unwxopels a 10-g dart. It 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 negligxvo 3x 58d8b ekuxwn0*9srn)zible 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 compona /iy 7:9a zz uujb8;rvf5x7dhent of 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along th;8:brij x ya5 fuuh97dzvaz7/e 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 balebopfl ji;+q3 1f-0 ythfg xu3( 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 stopping13;f 0yf(op x jtg i+3hqfl-bu force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a f9+/: t 7q8fe/j v6zzyk zdgvwwloor to a height of 13.0 m above the floor. What is the change in gravi v8fw79kdyzev tz:j/+g /qw6z tational 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 o 40 zmqyypb,7 sd)*xkan inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done b7z)bqm o4xyk dp0y s,*y 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 2.0uw (/8de2:1 .cjzpqxoarws w8 cm. What is the spring c wu prd wqw1zxo/a8j8 .es(:c2onstant?

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 ocobv/4n lr/ 1 .uu)avgf 60 N/m. How much potential energy does it store, when stretched by 1.0 c /o1 /4vguc.ar bn)luvm?

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 requiqk*. jq7jza oxe,1 p)cred to compress an initially uncompressed spring with a spring consta* jkqc7o.,zqpaj xe)1nt 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 stretch a spring of *c)s h8trkoltt- l e3(spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched posoe *rt)8( k-llh3sttcition 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 wukap6dpd+,zvvhga/ ut 2)6p7yi)+z is initially compressed by 3.0 cm. How much work is required to compress the spring an additional 4.0 cm?ahzyv 2p7d66w /d+)z+,gi au t p)vupk

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 ds; hsph1ru5*, in*astop of a 50-m high slope. What is the speed of the slier on reaching theui d sh;s*rpn5*1s ah, 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 ofc)9wd dq u9p;q6iez)cf the top of a hill with an initial speed of 4.0 m/s. Neglecting fqcedpu9; z) dc6iw9)qriction, 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 frictionle8 lxbr s,3bj vkpkttvq 9ru83p ,9nc9,ss inclined plane. At the bottom, it has a speed of 9,pb9rbv8rq n3ks ,pj 9vu 9t3xk,8tcl.80 m/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 tmbvx)+ibge ;(hbrar;;k(r )f he floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How faxkfg+;()mrhi ;e brv;)a b( rbst 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 fromg g 6p3 g7ohk3dvlg88:lczd*d ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To who8dcdg z :*p38l7vdh l3 g6gkgat 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 grou3 t*iutt84l)haaf-5 1v.s( crvwu veq: xkxg4nd with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relativetuhv3(xvtwaail 5qc r8 f4 tx:.vg*)ske4 u1 - 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 rest hr waaw3ez5n.9tr7 6eban0r1at 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 slope, which is 30 m above tw0aw96 r5 zrra e3b7t1n .heanhe 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 vhxqb* y;rm)b 1ncwhm e)7*b /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 th x7bb)mr/mwhq) yec*;nbh1* ve 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 bottom of a dip with a se es jos:e:s68)wx2j0nn9 nqopeed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the nessje0n:w xn js98)o:6 oq2 eroller 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 w ccco b3t;wi-u(/b:pof 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 r7m/r3l0odm 5p *bqmqaway from the vertical axis and released from rest. What wil0r*qmdpl/qm7 orm b35l 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 u x y87fpc 4jkuzhg;+.at 25 m/s hits an initially uncompressed horizontal spring with spring constant of pfy; 4+u k8c7xzgh.ju$2.0 \times 10^6 \; N/m$. 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)+ i:vhr5h0ja6 pqwit her 2000 kg car to stop for a red light. What work is done by the ai6tv0)jhqh wp: 5ir+ friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horqoi 6j22k ln4f b,/flgizontal surface is 50.0 N. If the initial speed of the objej kn22ogq/6lfi,4 bf lct 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 kinetic en x*2-42pzhs l7ll.8y mezdr bnergy. *2-p8s .nzdbl2rez l4 yhx m7lThe friction 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 horizook1f) i lm:h+kntally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mas+hl mo)f:1i kks is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high l d(y1oy:a*x jslope. If the work done by friction is l dy:j(1xy*ao$-6.0 \times 10^{3} \; J$, 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 planjsbc/ wy 9s)30 g+evmqj, (ware is 4.0 m long and rises 2.0 m. It requiwr/+ea mvj93ywsj b ) g,(cqs0res 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 rest at the twz yxduv: d3/35mq.f;dul) flop of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass a3vulxu .d)ffzd:;5wdmy 3l/qnd 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 ground withc2b0y yc7 onu bb;p*:+rjzg2 w a velocity of 7.00 m/s. What average force of air fric 27zy: b;cjc pyu nb+gbro0*w2tion 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 usin:f4b4 84dbk jqfdcc 4yg energy when he runs up a flight of stairs 10.0-m high,cq84y4bdk: 4f4 bd fcj 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 an8 aj8, efyufjbjw0 +ezx4z75 i:k+blb object with a constant velocity of 5.0 m/s. What power mus,7j8+kfbx 0yzz af 5jiul4b8e b+wj:e t 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 usedg835 rdhr2 gn urjq*c8, ef*dt by a 1.0 hp motor that runs for 1.0 hr? (1 hp,qd8 gr rucgrtnjde8 *2h3f*5 = 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 much for ,ym- 2vy+twn54r1t uegtr9z tce does her foot push with when she is tre,y t25t9gryw+m t vuzt14nr- aveling 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 power 4it,d2v+zzmr delivered by the engine? (1 imt2+rd4vzz, hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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