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

1#

What is the correct unit of work expresy;*b;- pb8qws)frnkx e *ikp, sed 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 i9asum .7:jc fpow.q j0f 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 az09v5he llgp o*m 6e4b stationary brick wall, the amount of work yo6 e50*4lhlvz pbe9ogmu do

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 being h3zid0vd d94 jqz1(ujv.vncq( eld there. How much work is being done inzv1(d9 n04( .d qduvjq3zci jv 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 horizontally forward at a constant velocity carryingyr91ao kgc6,dd s wcq:r; i -6dfi/r5k a 10-N objesd/ 9if,:cc gkwa-ik5qrd1;6d y rr6oct, the amount of work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then 3n.cf sed, ry 4nndb23returned to its original position. If the to4 fc3sdn. 3bdnnyer,2tal weight is 30 N, how 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 onv4tiwke6(g4hd bjs ) 9 an object do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign52i y- ,/orj 4zmjayxs of the work done by gravity while the bal szo m-ij a/4yrjy5x2,l 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, onswa *ph8nw -r7 a Force versus position (F vs. x) graph, representshw -answ8p7 r*

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 represents the work done by tp u p4:b-zlde8he force Fp dz4:ub-elp8?

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 o(lg 6v *8 qox0ceuq*q aqyy*a7uhfg37bject'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 o fcr*(0iukq0dk)jym w9 vtn 6:bject 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 kinetic ee)d7 z+ xc1gimnergy

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 speet ys z/dh/p8:hp;v28fwi/p kv d of the car. Which statement is true about the truck's kinetic phk8pv/vz8 d2f i:th/syw;p/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 mass oe, 6lw7tu.p ) 8lutqlwf car K. The kinetic energy of car J, compared to.w l7,e u put6tq8ll)w 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(ky3y7 p s7ibr original speed. What is the ratio of the final kineti7py kir37(y bsc 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 )zgfw: +a7f hca pebble is moving at a speed of 5 m/s. h+cw:zg )f7afIf both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speev1 v8aly8lgvmel -)u .d 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant brakm.evulv - 81lag) l8yving 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 brakec siv0 )yyf7a1/ jo*ces of your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would thec7yja)v*oi10 /cfy es car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elliptical orbiix,-1,:mreocb ot 6zyt. Neglecting any friction effec-z te,i6mor: oyb x1,cts, 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 prqqn (c l.z-s9kinciple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential ener;s y),4 )8e9 wili7isyzj yqkggy?

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 th4g t8r 1ui ywya0xu nn:5oc 5t5rde61je ground. A second object with four times the mass of the first if released from the same height. The pot1egr 0ny:cyw168 ad5x 54otiu5 ur njtential 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 s r)u **5vn ,dt3 rpate+e.jgoapring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring will bej5)r .tn etavd eg+3uor*ap,*

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a system sbg)q1s2 :9sds9 ka;b z:he3 .fqgosw

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 it rvs*-s(gef ( ydu)0potential energy*-ts 0rd)uvfyg(eis( 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 4bvg;ejbnw4 5 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 slidiqrpvf.waitk53o4iz5 r)p3 q) ng with equal speeds along a level frictionless s5fwqrp. p33r5v)t ai4ok iz)qurface. 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 mdbcv*l:)7zp j8p a .pi6qu342xwyvh uxr ; 1k$m_{1}$ 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 mechanicglz9 4-q9f)i6;eots5m4o uxu+sdzfd al energy for conservative forces.i;+fu9 l 6dxo4to- sqgz)5mef9us4zd

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 ail pz s4f7cx;:rr (air friction is present), to the ground below. How does the kinetic energy (K) jus:pcl fsz4;x7 rt 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 ki nq4zf9zw)xt5 rfm x6q7zk7e9netic energy. Do not ignore air resistance. How much gravitationaltx6zn k 9)f 4z7xm f7zqew95qr potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J jx:f)) lh;l. qg:s/mejq0 x imof gravitational potential energy. Do not ignore air resistance. How much kinetic ene.0): ejmmgxflqjx h qi)sl:/ ;rgy 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 of energy. bn5j2jhxa0n(

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/j;zdr7n:p c m1iy 0eb

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 expressc:m.ai)nkggx yp:1n5 ed 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 p0 6h goqp/t h1*h)yi 5/xmzuytower?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the timis*e0*xw9(rxqc1syt e. To do so, your power outs190teqxxi*y( c rsw* put 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 4sp jjpyn5;m z-:lc*jc/l t3+l xx 5rua constant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If the object weighs 90 N+bwv ;s4ucv/lv* 4rsv , how much work was done in lif v/4+ rcus*b4w vsv;vlting 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 iikbiogy) g9 er5 1t4 tblaun81 e1(a*an the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is th4in) 1tgigb y1bku*5e at(8aral 91 oee 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 pd1)xsgvpu;. *af8e mtulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the fds ;pm8 .tx *)gv1ueawork 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.7pph4x4at2tn t yb*c a constant force of 5500 N for a distance of 50htct* n xptay24p7.4b.0 m. What is the work done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5 sjbai8 ;xb67q500 N for a distance of 50.0 m. What is the net worx8q;7 bb 6iasjk 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 r u 0)wn53)jtynnd2(b gu9tye 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 az-jvq f59)ewh 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 ve6j- 5smotf 6eob c*7/uu+c q)tm;dm icy surface (assume no friction), with a force of 60.0 N at an ab6tm;5oeccf dm6ej)*oq/s mtv +uu7 -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 in2d 5y rd:ofc:ktrd9qdnxc )+rny51y: the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done whenncy: kx+y)ctr: rdr1yd:f5 5d n2oqd9 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 2np+w*- 5n h+k qklev7ln) arbof the force. The graph in Fig. 6-1 shows the force versus the object's position. Finp*keqbn rhn +-l5l7aw 2+v)knd 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 dir-v(kou+ i xjj9ohf8 x0ection of the force. The graph in Fig. 6-1 shows the force versus the object's positj+hjx809oki- fu xov( ion. 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 direction of the force. The graph inqtl5+idc *3ztt 8-b hy Fig. 6-1 shows the force versus the object's position. Find the wh+di3bttl-tz* 5cy q 8ork 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 apploeq lvnw9.gwari*b). ei;(s; ied to move a 55-kg cart (initially at rest) acroni*eq;wi o.v)e.r w9gs ;l(abss a 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-kg cart (initially 8j b8* hvjqkk9at rest) across a 10 m level surface. What is the final spee8q j89*j vkkhbd 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/8zdb-:epbjp 0bf b/u2 s. How much work is required to stop the /20bp-bbe8jfpzdub : 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 25nihgn4k u0.(a9znkr2 m/s, what distance is required to stop nikha9 0 nnurzk.(24g a car moving 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 propels a 10-g dart. It is cockes tp)+ki85y yzd by exerting a force of 20 N over a di+y5 zpyskt8) istance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N9lj6 lerz ) +4ot:a/tbgskgr 9vsm :q: and a vertical component of 60 N. The force is applied to lgjrot+bs49:z)te 9 l: /qsm:gakrv 6 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 is shot horizontally into a bale of hay, striking the hay bgj z+e, qmdul61 l exc-e;t42with a velocity of 60 m/s. It penet+ qtc;jbdex l le214 6,-guezmrates 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 of 7.00 m above a floor to a hei6pq)zz a,l+j l pt-)poght of 13.0 m azlp),p)oa-6p tl j+ qzbove the floor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m long and rises 3c8zgj/ 5i) crxfjja;q e3/ to2.0 m. If the plane is frictionless, how much work was done by j3 f3cix j5a;q8re/zjg cot/)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, caf9j wr4wm48m8g gv4f;hx/qd-d sbkj*uses the spring to stretch 2.0 cm. What is the spxrbjfkv 8gjw/q8f *44wd;9 hsgm4 -mdring 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 poted c52q(s c xv07*serkqntial energy does it stores*x 0s5 vc(cq2k7 erdq, 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 r pj1 ogiek7q4j.u36(zt8nigr equired to compress an initially uncompressed spring with a spring constant e7otj npgqgzu.( 4k 1683rjiiof 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/u/gha 7 ,etjs aig.y0/m from x = 0.20 m to 0.25y. sjg70taie u/a/gh, m? (Assume the unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3.0 cm. Hui6*axq4mo l+ be8/ ky8a730puwzuz m(uv q9wow much work is required to compress the spring an addixauuy woe /3qw9zi7bzk 8 a08vp* u(qmu+4ml6tional 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. What is 9:d2:pnlno pnje14d0 phu4 zxthe speed of the slier on reaching the bottom of the slope? (Npe:p914h dup n24jndx0:zno l eglect 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 ofqw*zug8oc l6d*1r;x r f the top of a hill with an initial speed of 4.0 m/s. Neglecting fri rgo*lrcxz8q duw;*1 6ction, 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 frictionless incr6gq 7 * 8aq5v ,blsqake5 sdv,gr4yz)lined plane. At the bottom, it has a speek,a qlgr*var6s 8 zyq5 qdgv4) ,s7eb5d of 9.80 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 th md oavjf0 z0/t)+nux2e floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it movnfu02ajtoxm /z vd+)0ing?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground levybs;fgnx 7da6v.5rz5m f qkr10 )rr9w el with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does itrafz.xb 5 ;)m1rfnqkdr gyw9vr5s067 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 kinetic5z76)1amwpn)n, n bhhekvid, energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 h,7) dihbz ,1ep n mvn56kan)wJ. 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 from rest at a point 45 m above the bottom of a dip (tn.qbsqw3k60c :vw d p28d zh4See Fig. 6-2). Neglect f.vq8 2hn:wt 40d6dpz3w sq bkcriction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m abz0 nax3h (gy4bove the bottom of a dip (See Fig. 6-2). Neglect friction, wx(0nah y3gb4zhat will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom 3/0 xo73ppa 2e (fx0kvfipqujof a dip with a speed of 2/ i vxu 7j3 o(peqfpxfp2300ka5 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 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**zzbt (tr8 we of the ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 f3mai8q cz)xu *4pa;xcm away from the vertical axis and released *3) ;axaq 8uixcz4pm ffrom rest. What will be its speed at the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncomprescth( h:7doqzv 95dd/l7wy 1eaj7po9osed horizontal spring witho h7cqd7a1lv9y jdpt h75/e9(owdzo: 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 redj:i* eb6x9:cvc y;pzp light. What work is done by the frictpivz*6e j;c9xyp:c :bion 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 60mfqb1dzp6n5 8tjq)cii.)ff + .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 before co6bf8iztfqq5)d ci+p mn. j1)fming 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 surfauvd1wup50l hmt vg)-q99c7noce. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far wilm50nvv p79d)-l ctg19ohwuqu l it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level surfa*h 0a9x.ev iooce. The coefficient of kinetic friction beo hxav .09io*etween 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 resj( gnut,p*p0i7 yoh5l e:mc*st from the top of a 50-m high slope. If the work done by fr0pj,mo 7tc*yeh5si pugnl *:(iction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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教师可以抽题组卷或一键复制本试卷，布置为在线考试或在线作业，全自动判分成绩一键排序导出，省时省力

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed u(6og- .flu4ebbxnr z5p an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitu( lexzo4rnu6fgb.5- b de 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 tv6 rle)njkv 6/op of a plane inclined at 20e above horizontal. The coefficient of kinetic friction betwj v/ekvlr6n6) een 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 strik5eo, :czrwkjy/ nz05kes the ground with a velocity of z50c nr:eoz jkw5y, /k7.00 m/s. 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 when he runs up a fl51dc ft7iedg)wp 1oh*ight of stairs 10.0-m hifhcgpd1t )o71wd*5e igh, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocit4db99utvs rat1anp,u2u i(g* y of 5.0 m/s. What power must be delivered to the obrbsaut t(2*v uu4g 9,pnd1i a9ject by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp mj*mz8vbb 7z pa-d q2-qotor that runs for 1.0 hr? (1 hp = mp* vqdaq78bzzb2- -j 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, d2os.pk mkuvqs+-j7 d0 5ryv W while riding. How much force does her foot push with when she is traveling adov5r-s d uyqpk0.jmk,s 2v+7 t 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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教师可以抽题组卷或一键复制本试卷，布置为在线考试或在线作业，全自动判分成绩一键排序导出，省时省力

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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 t5tj ,v)yp,ty p 0:ejsco 25 m/s in 7.0 s. What is the average power delivec ,jsjt)e 5pvyy t0,p:red by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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