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

1#

What is the correct unit of work expresse9 7d ea+w( sqdou-3xdhd 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 if there is no motio2 *jrg4g; hej1jpv(gqs nf(r1n?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, theh9ij )ptluhx a*--h g- amount of work you -xh-hji) ah -9*upl tgdo

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 liftyl :ze 6vwmf t2m52d+ved 2.0 m vertically and is being held there. How much work is being done in holding the box in this positionf lvm:e5twmdy6zv +2 2?

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 7ea 0k:vhts9 vxfvow,we(9 xgj. u(q5orward at a constant velocity carrying a 10-N object, the a,e0g v9shk ( 9uo5qaf vjwt :w.xx(7evmount 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,xmzls((iot8tp)h bm53 tg c( m then returned to its original position. If the total weight is 30 N, how much work gi 8xpm5omtcth ()t (l(3,bs zwas 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 wafbfij: p,;9z tcs 0o*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 straight up. Compare hrg-u /n:dvz( the sign of the work done by gravity while the ball goes up with t-h vru:gn/ zd(he 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, represe89hth gcjzytv *+*v4-(o)utw7 pfle ra:c gi9 nts e+v48oryu* *jvth9 iz7 t)wfpc:t(c -lhagg9

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 poskmc *93my fxc 4w- /;uq xsyjrbequ94.ition (F vs. x), what represents the work done by the34u ;c . yemrm99qxu sj/xf -y*qcwbk4 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 the object's kinetihy+x* + ixxxs.dsh)xsb 60pm2c 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 :c p fnbg6,m4o1) xfujnegative, 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, th1jxw(d4:gtc*kt t s6ken the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twice the speedd3tb:4jhj9g) 2q8qp r fn+yfv of the car. Which statement id29) fpbjhjq q g8r+y nftv4:3s true about the truck's kinetic 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 carql(cc 2c,uexr d;q3e- K, and car J has half the mass of car K. The kinetic energy of car J, compared to car ; rdcu cc-e3qxe2l q,(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. Whatv/m xv0ks 8(dy z7zxx5 is tm/58sxzv d xy(zkx0v7 he ratio of the final kinetic energy to 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 spedc,a8 nmk)f,ded of 5 m/s. If both objects have the same kinetic energy, what is the ratio ofc 8n,akdd)f,m 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.wum1b+ dud;8wxum:(* efh l ;a0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the (dfl;8 bhmwwm*1xaed+ :; uuusame 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 csu6y b;r 4/+w9 s5h knde0acptar in a panic, and skid a certain distance on a straights6 + 0 u/4cyne5srdh;k p9wtab, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant masn/ )b:f5mes( xk2zgfls orbits the Sun in an elliptical orbit. Neglecting any frictiofeg blx2 (:z5m)fks n/n effects, what happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

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

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy prepv;ko4 ui 0w2inciple.

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 potent:n 2fxrzlr :3nc.s*nvzy-a 9 xial 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 fr8j/ le6cocjs et 0m5yo e;x+j.om rest a height h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the second object compared l5o;.0c6cs jjx oe jee 8/yt+mto 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 th q;wm enh :o+q69totrx8bp b;;e end of a spring causes it to stretch 5.0 cm. If another 0.n t8 trb ; xqqoe;w;ph+m9b:o6200-kg mass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy ozkged wv*/:q r-g1uq2na29sz f 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 potential enyb.u8ngx g q8,w khr)5ergy U.ykwnr.h g)5,qgb 8 u8x

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 drits/z( s 7)ydb6mh g+,c1s7g5dcyh bak ving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are sliding with equal speeds a7f ugw8l :ixid6 f)7ialong a level frictionless surface. Tif8l d77gi)w:f6x aiuhey 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 mav1c4euy5 7g $m_{1}$ 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 consex 3pvln7p/i x2rvation of mechanical energy for conservative forces27i3 lxpxp/vn .

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 p2+:yvedr*com 5;jvzu resent), to the zjvv+;5co yru2d:*m e ground 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 gain 1mrxcw0f vhruy3r/q;8(op kc.gar2p z/y.5 fs 30 J of kinetic energy. Do not ignore air resistance. hfyr(. .frv5g 1k/rm;u 3o 80/rzacqypxpw2c 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 distanc in+ fhv+3;e-guka xi-e and loses 30 J of gravitational potential energy. Do not ignore air resistance. Hhke-gui ax;vn-+fi+ 3 ow 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 conservation 0m,pb pty2 2yx vs1-ueof 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 is9- j)bdrim o24nx rpg bu6x.l.lo y2w6

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 e lmck:- :a dp c6699kjtnuoli+xpressed 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 poxd )z+.mrn-d mfmncq,jgl0 8,wer?

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 yesterdaylc-: kx+ 9dpt- mjlc;i, you did 3 times the work in one-third the time. To do so, your l jtclp +-:i9- m;xcdkpower 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 acceler7t)ts,hwb1yx ation, 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 held there. k+f+ymtsry 4y/if(q 71fhbf9 If the object weighs 90 N, how much work was done inq by(+h/t7f mfi1 f y49rskf+y 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 2uxf6x0;heq6 nuy1+z5ubxd- gdkwi 11.0 m, at a constant velocity of 0.50 m/s. What is the work d1 nx 665+ydx-u10uhge;d fx zwuqik b2one 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 constant f ,z86xd3rvijqorce of 5500 N for a distance of 50.0 j,xd86q vr3zim. What is the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with alawjuz;1wb 3 )wxj dq-nqy4dm74l,2 g constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight 1jn,z ;43-)qx 2ld47g d wmaww uqlybjof 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 ws 1jkr*jwm x1j(t)*er 5.yrg of 5500 N for a distance of 5mtrgrsyj.j*r)(wk *ej11 5xw 0.0 m. What is 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, t-t)firvi p ;t0nlr6 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 fruit slides 8.0 m down a ramp, incline*1-oogw* ru9nc ctcj/x o9i9k d 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 surfbrixng4kzx9;y98-fe ace (assume no friction), with a force of 60.0 N at an aifenk9x r-4x9b ;gyz8 ngle 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 i - +*br,tp/;cupycjptn 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 f ,p;y/rp+cp*tuctb- jrom 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 fori26 tu5b el8coce. The graph in Fig. 6-1 shows the force versus the object'sl 5ei8 tubo2c6 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 the force. The grapez uwtfto239*j;fr 9 th in Fig. 6-1 shows theeo3ftr* 9z;tftw92 uj force versus the object'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 directoy+g )b4(3xl(veu o0d o):kkda3ra ejion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object mo 3 (ebuklx:o +0ada)(4 jev)o3gkryod ves 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 i)yxj(vg4z-c e s applied to move a 55-kg cart (initially at rest) across ay4v j(zxc-)ge 10 m level surface. What is the final kinetic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-k8l2 pl sp*a67xm;ztts g cart (initially at rest) across a 10 m level surface. What is the 7pm zp sx*s;l8t6tla2final 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 5.04,;ydz (j ivhsgxa5e+ m/s. How much work is required to stoph vgy xi(jae+d;5, 4sz the 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 2i-ic :yynl4kd y6p7t uv.8/rt5 m/s, what distance is required to stop a car moving at 50 m/s under pt864 nii.7:d /-ulc yktyyrvthe 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 cocke0:di njvs5a:l d 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 h5 js:d alvn0i: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 horizontal component ofr0*5+djg;qpak p b8vd 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 horizoj+k ;vgp58add *bq p0rntally 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, spy3v yf j *4.oqn7j7lalsv i)5triking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm befooin7)a4l p.j3*ls7jyvq y5 fvre 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 yjei s k v4 c.a. h.kahaz3wfdqyf5-9d:ff0,+of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational po.a-h 5wqkef .f az:d yv+j3a ,0.scfkd y4fih9tential 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 4.0 m long and rises+nv f* w5x+ue* e,enrsw3 fom. 2.0 m. wv +s* ,+e ron. w*xfueem5nf3 If the plane 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 2.0 nlz,dbc. 1,aicm. What is the sprla ,z,.d 1ncbiing constant?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much pdvt y*b5z-e )yah e)8gotential energy does it store, when stretched by 1.0yh gz5edy)*veb8t-a ) 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 re;p3 f7pruclu -a1j4.f-dowghquired to compress an initially uncompressed spring with a spring constangu opf 7ucpw1d3;fr-4. -ajlh t 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 i**ow -ktws -ostretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretc iso-kw *-two*hed 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 consta .(6vto*ebr gynt of 15 N/m is initially compressed by 3.0 cm. How much .e v(o6bgytr*work 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 high slope. lfeaz4+2bw hyqx-1u-8f9 s gj What is the speed of the skier on reaching the bottom of the slope? (neglect frh1q+4x sj2 uy9lwgbe--z8 ffaiction)

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 cjc ofa8o. 6nc4e uw:)pl48wz speed of 4.0 m/s. Neglecting friction, how fast will she be movczc eu8p8f:.cjanl ow 4w4 )6oing after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bo* )x1fonkq* 7- rcf9 dvk47s ncrsww3uttom, it has a speed of 9.801r77* sfdk9cf*o34 s)w unxn r-qv kwc 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 the floor. When it is 0.70 m above the floor,0torak a8o-u( zc2n7a (ha. ly its potential energy exactly equals its kinetic energy. How fast is it aau(72-k har8a. y(olt0oczn 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 fro-+s8ceg aqa4/n6mh elxd88w cm ground level with a kinetic ener/a l8wehgn8dm6c8 eqscx+ -4 agy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic enee j;mcb+64 7v oz-tvvvqo/7dzv-jj8 lrgy of 220 J. At the highest point in its trajl 76+j ot8mv -j7;cqvd-jz/zvvb4eovectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts df6u-f*6c5-om p9a epha - pf mvtb,d,from rest 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 6d- p*9 haa-mfetf,c pump,v-5 d bof6of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a pointlrn e lzk0qh xg21a80a)pnwsm. + v0:d 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster av0xs. d2+e :kgzpn)mrlla 1 hwn8 0qa0t 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 abovez5cax9fwi,wma f9, 2 r the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what w59w rf,xcaifwz a,2 m9ill be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of i*oo m.t 8a* xwwrr/y-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 2-kg pendulum of length 50 cm is pulled 0.17 m awa; s:tts ;gi)tzy from the vertical axis and released from rest. What will be i t;s;tz)t s:gits speed at the bottom of its swing?

A. 0.229 m/s

B. 0.611 m/s

C. 0.917 m/s

D. 0.764 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 initpo-4arm+/vjfj *u)t ne:ml/3-jb tk vially uncompressed horizontal spring v:k l opf/aebmmtjru*v j4 -t+)/j-3nwith spring 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 rtpvsjr9w) 8p cf2)9c7h jp2k ced light. What work is done by v)9thcppj9pw28)rcf sj72kc 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 fo)g(szcq b9x5v ;os 4mirce between a 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide be9b( vc ;zo qsim5s)gx4fore 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 onmv g:ambv. n ma9 t-g0m9x)3blmi4ev/u7jmw ) a rough, level surface. It has 24 J of kinetic energy. The friction formm30itbvv9l/gaa7g.m)mm4 x -mn9b uvej):w ce on it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass okro2f: 2ctm*;yr9r*w fpiu(en a level surface. The coefficient 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 iw:;f9 2cu** (2rokry rfpmet 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 slope. If the,ovox zfdd.n3 (bl 0u* work done by frictio 0uxv(*.l3ood bfnd,z n 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. The planau c;r0s 2dr-oe 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 p2 rcuosrad;-0 lane. 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 re8exfo xp31a) 6-zghhxh flx6 8st 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 speed of the mass after sliding 4.0 m alonz8h3e xhgxohxpf6)8x6-1 flag 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 drowcd328x umv b,a) 7hrcpped from a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s.87h3c da, )b rwc2xuvm What 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 whenv 535cq1 7ov hmbh+vh-ab3-ndjzk ml 2 he runs up a flight of stairs 10.0-m high,cm3lh bjqvvbn5-v odh23hmk +57-1az in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an hz4p)q9cg u3o object with a constant velocity of 5.0 m/s. What power must be delivered to the object by the4zu 39c)h oqgp 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 run cvsmz56tesm a.-t* 5vs for 1.0 hr? (1 hp = 746 * .565vv-tsmezsctma 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 mucv+i729 kiw 7dos4zqk ah force does her foot push with when she is traveling i+viosa747 qkkzw 92dat 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 7.0l t ,5(thh*( a64b3egf ;okelfef0auw s. What is the average power delivered *hehka( l 5 4faogw ,0e3e;b6utflft(by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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