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

1#

What is the correct unit of work ex/v, +lw+ taqkbx*-3dp6 scqqopressed in SI units?

A.

k g m / s^{2}

B.

k g m^{2} / s

C.

k g m^{2} / s^{2}

D.

k g^{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 if there is no mo,3 b dmt(xcsu/)g axy,tion?

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 station; 49sft +cnaxsary brick wall, the amount of work you da f st4+s9nc;xo

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 beik12rju3 y 8bvcng held there. How much work is being done i k12cu3y8vjb rn holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horuyg*lbpnvx(z .f4(gm5 -xx y( 4mcz e-izontally forward at a constant velocity carrying a 10-N object, the amount of workb n4-gmy(-m xpgz5x((.vuy4e *zfc x l 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 ver 28iki /5cjuzztically 3.0 m then returned to its original position. If the total weight is 30 N, how much work was doikzuc /25z j8ine?

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 w-dk m/bdrjw.1 ork 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 straighczv g *m5rezgth ( 9gncd2;je0/ o3r)ut up. Compare the sign of the work done by gravity whil( e 30gcd9 r r*o5g2zhz;jenv )mtugc/e 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 p 0lrr6o;b+13mqza,gh 3a-2v nviof du0 7oraaosition (F vs. x) graph, represents0ifqav ,aavrz 0+au1 6nrlo-hb7 mg3odro23;

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 positi1j zdr2ia/p1bon (F vs. x), what represents the work done by the d1i 1jz/2bpa rforce 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} m v^{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, thrphjy)mw 7n:yu 9 qjapi (gt( 6ev+l44en the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, then the ob-lcte adbq2.rg 6gu,4ject'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 thb t)si3qrmv*v9sqmqd47,72mmdko9 d 1 - suche object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car,a:iz4rx 9ae6nis0l4mkpp : z: and is moving at twice the speed of the car. Which statement is true about the truck's kinetiri:k6xl4a4m: nzpa:is9ze p0 c energy compared to that of the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mq;fd;yhq:1qz fdam271 xgf9 rh1se, hass of car K. The kinetic energy of car J, comp11zhfmqqr9;s1d:gf fehyx aqd 7h,2;ared 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. r mj5k+y0nn kej+ oz1,What is the ratio of the final kinetic energy to the initial kinetic enjnzoyk0+ke n m5r, j1+ergy?

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 i198 oi j2 6h,bvfrodvbs moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is2fj 9bvro i, 61bd8voh 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.)wa0xum i0h;ex0wd +7 upq-fz0-kg mass is moving with speed 4z aued-hx u )0mp0q;wxi f0+w7.0 m/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 .45t3gzoycu n8+a b1tpfmufe3nli75certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skim38i7u3le u no55+b fnctpa1f4tz g.ydded, 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 ellulq4 )f /kgzrh- lsi7x)o b1l(iptical orbit. Neglecting any friction effects, wh)qg- /ou )74(ll1zrkfxbilh sat happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy pr74aayvev7 z-fux r fb 8ilvwc))l (5(q9sbyn8inciple.

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} k x^{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 systej;lbciw6 yr 5cq4k2:j m to have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the x0zxmu 8t:4knae)0boground. A second object with four times the mass of the )kzto 4 u0xnx:a0 be8mfirst 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 causesqgv9 *5k0(v kqc.zvfs it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential en*(5q09 qcvzf v .svkkgergy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of kdtv: o b. , 7xkg3t),gotvt3ia 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 (wv9lg4 gp k5e;a0y tvyto06pits kinetic energy K, to its potential energye y0 0yt 6v( 59goavpgt;pkl4w 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 hily(k7l )0f*zrp f y-kv6)jnduxd:s e:8ua9vrnl.

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 eq6k h1zrzw: j;wual speeds along a level frictionless surface. They both slide up the same friction zk 1z6whj:wr;less 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 :d1+cpit 77v;kv qkg k

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 mechan) qxwvky(hx8.hj 7 od4ical energy for conservative forces 7)x kxoy4vhh(.jq dw8.

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 t ;gr/lr b l-rm+nqz -v q97i704gqqqgjhe air (air friction is present), to the gr7 r-/ql 7b-4zn;0vg+m rg qqrqjq9 iglound below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic ener:x*lb+s6bv;0 dtz a wk b;;acsxpr03c7*i htmgy. Do not ignore air resisba 3s a xs+*:v cwrlimzpb;0;0k 6t;tcd7x*bhtance. 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 distasad1 t7na/lh 6 f2ayc;nce and loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic2 nalsa7hd 1;6ft/ac y energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation ofos(j8z m.ev5o 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 isbvu2,84m39 ucr,uab yv t+l.qab;n nt

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power 3 wh*)ra mghw0expressed in SI units?

A.

k g m / s^{2}

B.

k g m^{2} / s^{2}

C.

k g m^{2} / s^{3}

D.

k g^{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 powerlh2t+ fx)8/cz7hl iw g?

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 w;do hk7qi)fsq7k0 3z w2j)gc york in one-third the time. To do so, your power output must q c2)z) 7k7fokq;dsj0wgyi 3 hhave 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 accea7o ,t3ltcl:n2gtag- dor 01/fe1 mkeleration, 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 heldyxja p8gux,8zu.5sl,.r3 zk j there. If the object weighs 90 N, how much work wa,al gk,j pj u53s.uxx8z.zy8 rs 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 dist/x qfu;xvnp.faw 88 lvju74f jw/tw 4,ance of 1.0 m, at a constant velocitjp7w v4v lwun.ft wf/x,afu/8x;jq48y of 0.50 m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constantr8j9mo 80kvu fbtj: n: force of 5500 N for a distance of 50.0 m. What is the work done by :nftjkv o0 b:j8 r89muthe 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 force of 5500 N dagij s.p8m2:for a distance of 50.0 m. What is the w:gmp d2s8.i jaork 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 u)ci r8+kex) vipward with a constant force of 5500 N for a distance of 50.0 m. What is the n)vkic +xeir )8et 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 along a w kh 8e6( 90o)yjjprbi

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 slm9g p(btc6sgk *ju6r 6ides 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 g*ip kw 0:uw3vicy surface (assume no friction), with a force of 60.0 N a*:igkw3w v0u pt 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 1v/c q5*+9dn8 x ame+ki hcdgwin the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 2.0 1e8+/5c qwg dv+nmk*ahxidc9 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 for*zdhs ol8a3ekwd 61w x.uk9c*ce. The graph in Fig. 6-1 shows the force versus the object's position3zu* e o.w6l xs8*1kh9ackw dd. 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 y+,:mrvxv q0d of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the v,r mvxqy0 +d: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 directirq)hfaf x31j) 2kr4 wdon of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 6.0)k ffwh2 43dqjr1rxa) 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 (initid *gn(k/8xwb.lzqf +zally at rest) across a 10 m level surface. What is the final8 flwqnb* xzk./d(+gz 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 move a 5i9ym m. 3vk k*foa+ka95-kg cart (initially at rest) across a 10 m level surface. What is the final speed ok+a.m *v9k a3imky9 off 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 a(s;r05swq6gid i lju): 9n wfwith a speed of 5.0 m/s. How much work is required to stop the mass?i w05qurj6n: )s;dg f(wai9sl

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 c9pk bj40qnwr .wqczkx:v85*zar initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s wz4k vzxjb.w9p rnc80 :*qq5k under the same condition?

A.

50 m

B.

100 m

C.

200 m

D.

400 m

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart. It is cocked by exertinc(: uajhee1c/)ogdnsy- 0q 4s g a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring h(u: descnoge- /caj4qys01h )as 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 horizot-0:q sb akbd-ntal component of 80 N and a vertical component of 60 N. The force is kbd-a t0q-sb: applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart'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 iqez - azj4vm40s shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/szezv0ma j4 q4-. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A.

45 N

B.

90 N

C.

180 N

D.

360 N

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height o upm(sn8kdi.2 f 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational potential e2m i(kdp.s 8unnergy?

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 incline,blk)kvrw o/-bxa jii0s638 b d plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done bwrk) ls/ jik,xib36bbav o- 08y 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 2.0 cm. bgy25 yeeaf-:fs-0pbWhat is the spe -fafg5ys2 b-ypbe 0:ring 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/*1usoe(:r:xhv - ywq5s4zbbqcfq6 3s m. How much potential env 3 sqq6:zsxysubh cr e(:o4w5* b1q-fergy 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 uncompxkvb9o 8a0 xf9r0qe;r ressed spring with a spring constant ofq0 809xf ;o ravrkb9xe 25 N/m by 10 cm.

A.

0.10 J

B.

0.13 J

C.

0.17 J

D.

0.25 J

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N/m fropjqeb7 so*f+3m.z n nuzv9s65u9v em9m x = 0.20 m to 0.25 m? (Assume the unstretched z9feu9j+*m5 9 bv ou6 7zqes.mns vn3pposition 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 tk 9ra540a bpyof 15 N/m is initially compressed by 3.0 cm. How much workb p9t40ka5rya is required to compress the spring an additional 4.0 cm?

A.

0.0068 J

B.

0.012 J

C.

0.024 J

D.

0.030 J

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m hiyha71eg * r u;w3as igg52-j-v mse2kogh slope. What is the speed of the skier on reaching the bottom of th a2;e--rvkse7wmgj 2iaug1 os*3yhg5e slope? (neglect friction)

A. 22 m/s

B. 31 m/s

C. 38 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial speed oo35qct p63u qo4y1 qxezjg: j58z bl,df 4.0 m/s. Neglecting friction, how fast will she be moving after dropppe85ldox,31tbj o5 z:g6y 4 cqjz quq3ing 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 bottom, id*ntk+ 9doex rsp/zmv)5 f :v9t has a speed of 9.80 m/s. W9z rmd pvd/sfot+)x:*ne9 kv5 hat 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 hytsh ,o..rb+ the floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. H rh..hsbto ,+yow 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, bla h p 7ypp;p1l,eisq*uk6cxcqd1*3 x0jsts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To wqq7lsp py6hx0 jp*e*,u ;c 1ixkdcp31 hat 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 7apxiqrj+e:o zr -61zthe ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To wha-qerarx: jzzi+71 po6t vertical height, relative to its launch point, did it rise?

A.

\frac{220}{m g} m

B.

\frac{120}{m g} m

C.

\frac{100}{m g} 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 r:pmky,p4ty0j z1ksk4;s )pdm est at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom o)dp, ;0mpk : mp4k4kstzyyj1 sf 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 startsd 6dgd-dc dh30wec;t) 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 top of the next slope, which is 30 m above the bottom of the 0cd)6ddd-;g d3c whte 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 b0 f*en j g,p,u jnn0i/edjr (:y6mr7ybottom 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 botten,7g uijye,f6/jrp(nyrb 00 j* dmn: om of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball f6z xg f)+cfh)tynk d +/vec92at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2-kg pendulum of length 50 cm isr wrrfvo*/**h)vxzq6w 1du9 o pulled 0.29 m away from the vertical axis and released zwo1w6v*f) r*9/u*orrqv dxh from rest. What will be its speed at the bottom of its swing?

A. 0.404 m/s

B. 1.078 m/s

C. 1.618 m/s

D. 1.348 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 horizontal spr9nvtbi)z ;np9ing with sp)p tn bz;9niv9ring 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/s3i46n vh(uoo: rp(ra zsab9 6r, slows down her 2000 kg car to stop for a red light. What work is 6n 4o b:(iz93rsrvaup( oh6radone by the friction force against the wheels?

A.

- 2.2 \times 10^{4} J

B.

- 4.4 \times 10^{4} J

C.

- 4.84 \times 10^{5} J

D.

- 9.68 \times 10^{5} J

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force betwaq -mf vwgk-thxh); 2im:;z,o een a 60.0-kg object and a horizontal surface is 5i)h-2 ;wovz:ax ghqk; t -mmf,0.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A.

15.0 m

B.

30.0 m

C.

375 m

D.

750 m

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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, l;q - 9vb9n0gi0 w h;wumfm8mssevel surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far will it slide 9n-m; uw89f m0shwisbmgq;v 0?

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 rwa89 ;n i7:rezre;ae to a 2.0-kg mass on a level surface. The coeffea8w;9: rnz;iar7ree icient 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 tqe.6c+p g:iz che top of a 50-m high slope. If the work done gqei: .6+pcczby friction is

- 6.0 \times 10^{3} J

, what is the speed of the skier on reaching the bottom of the slope?

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane.sl qwrz3*m3(q 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 l* 3sz(rqq 3mwaverage 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 th+eyir -hsg5mh7) y/ kne top of a plane inclined at 20e above horizontal. The coefficieig/sy-5hr h)nm+7 yke nt of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and s*: h/bq .l-moxocgkx4trikes the ground with a velocity of 7.00 m/s. Whx:xomc-k/bqg.* olh4at 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 he runs uc6, w f(8d bfw*r,odla)hipo*p a flight of stairs 10.0-m hd*lr b6a*wio hdwo8)p ,( c,ffigh, in
8.00 s?

A.

75.0 W

B.

735 W

C.

4.80 k W

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 fj93zi d0wd m-of 5.0 m/s. What power must be delivered to the object by 0w-f9jz dd mi3the 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? (1 hp )0gnpj(1betc/ -:w g qb-uxge =pg-jxt b-)u0:w 1gc/b (nqgee 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-a pkw//tz -cf of 500 W while riding. How much force does her foot push wi/z-fw c pak-/tth 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 todcf0xqm 5t/g) 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 htxcf)m0d5 /gq p = 746 W)

A.

60 h p

B.

70 h p

C.

80 h p

D.

90 h p

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