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

1#

What is the correct unit of work eqk dt:l x5;hz82ihonysl. )v1 xpressed 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 sys 2p7 ft5 ,ax8pq4awvll5br 1jktem if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick /frfwqq s tfn,)b/*(n0g/jfgwall, the amount of work you/fnq0b/q*, j r/wngt)f sgff( 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 h mh4x5nb - 7nyra);-txp6 eb)qjrn-w ield there. How much work is being done in holding the box in this positibbmrnx)qwtx--4 nan56 h y;r 7pej-) ion?

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 c .kis98qfbd j3;*oadat a constant velocity carrying a 10-N object, the amount of work you do i .dc;a 93s8f* odjqbkis

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 the l 2(-st ntm7jaa91qqf/1 uheln returned to its original position. If l1 12l atjhqestm nf7aq-9 (/uthe total 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 acti0,* fqz iqsh+obq/u2 ing on an object do work on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign ofcbktl lh t6q7a76ccf9v1 tr84(ttc( w the work done by gravity while the4cb7v7ltclf h at66q t(ct(tkrc9 1w8 ball goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x (cve3*f*m tgl) graph, representsleg3*c* mtvf(

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 positidc 0o5. luygl:0 xsi3lon (F vs. x), what represents the work done by the force gllyu00idcl.35o s:xF?

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 positiuz5 cds- d 2s8*g,8rleiiu(wz ve, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negative, tyimhv (k0d;a2 jv7u6lhen 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 kinesi;2uylqc r sp3 q+e1.tic 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 ir. lfjuq0pb-4 s moving at twice the speed of the car. Which starpb-j4ufq. l0 tement is 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 car K, and car J has half the mass wt r (c,ix1il,)jg(i7 ffgty6 of car K. The kinetic energy of car J(rf(wg i 6ytj , ,ltcx7i1fg)i, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speed.pi n8 qmlqo1,cq(byj6( h 5s0t What is the ratio of the final kinetic enerbq(p( y5 jo t18imlcqn6qh ,s0gy 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 speea ya9wxq3b-/ ld of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the -x3bw/aya l9 qbrick'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 1.0-kg mass is movingrx+i 8,2 klljq with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object tkli rx8jql+2 ,ravels 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 s,zd: ym9zi 6 nvr*;o4 g(mcvr0aj,msekid a certain distance on a straight, lev ;r0*jcsraod4,z,zgm:vnmve( iym 69 el 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 mass orbits tp :a5s,.sy )4bbuth+c5m ff nmhe Sun in an elliptical orbit. Neglecting any friction effes.ybn mmbu t4,5 a)h:sff+pc5 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 principjx3t7 6 zrcuhtpu (m;,le.

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 ha5t t bg)pv7ycf:l2 ,zzve 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 ground. 5ec1yfex*q oo; q g 9nbx9k,f/A second object with four times the mass of the first if released fromk,b9f;e y *qooxg5 cxq/e 1nf9 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 ca.ni/.v j g+mlz/jjcy/ uses it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spri+ //gi njyzj.lcm/ j.vng 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 ene0x qxtvs*e8 sk5x/5u nrgy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tren,6g u- ixzdjxk5)ahf3i 9:x sfet/f 5e. Compare its kinetic energy K, to its potential energy U.gzk, jes /: t6 )a9xf -dh5i5ni3xuxff

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 up27eu l0ifd q; i ud) cy8r8ht:mb7obn9 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 sp(0hb-x52o jnla;j*col: eo5n j i e;cliding with equal speeds along a level frictionless surface. e - 0lhc5: l;ja ;o(jxibcjno5*epo2n 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 3z6j1o 9yth7,qqr khg 4wcu+q$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical eners- zbu klj.olw/ -,dp:gy for conservative forcesso pldkw -.l-zb:j/u, .

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 ao0 m1qde1jikf uf w-58 building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the ffq10dwe jo8k 5um- i1building?

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 energy. Do pi* i1isvthw q*x66r4 not ignore air resir6qi 4pwvtsi1 ih*6* xstance. How much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loseo- eu)*aph)x, 6guk oqkq1 vl:qs(ks1s 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did th 1k:, qlsoqa qeos g)hu*6(-xv)pku1 ke 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 conservationcf604.r yq +jkj oybs* of energy.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t ishqqu632alc j5qj+n qcr n((s/

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 unitnug7yx n k,*ct jqs.8:0qtl4q of power expressed in SI units?

A. $kg m/s^2$

B. $kg m^{2}/s^2$

C. $kg m^{2}/s^3$

D. $kg^2 m/s^2$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is nou8*z/adsgw k l0ehl 77v.tk :xt a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the time. To do s1 :87pkebdofnt1 9aflo, your power output must h71fdoafetb :18 9n plkave 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 acceleration,q u yip0/c7si, 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 vertic-ghy1p a7rj2rally 2.0 m and held there. If the object weighs 90 N, how much work was done in liftr2 yr-pgj1a 7hing 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 inh--sunhl1+q yn 1cak636ukp s the air a distance of 1.0 m, at a constant velocity of 0.5as1u3hnyc 66kpnqh - 1-luk+s0 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 constant force of 5500 N ,tq7 rciv z :,cz3zqclq,0ea;for a distance of 50.0 m. What is the icv 7;alzqz ,,q ceq3t:0r,zc 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 a constant force ofl k. m4npg2lk+ 5500 N for a distance of 50.0kpk n+4.g2mll 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 5500 N for a dirs:t /m 0gqt4xiyga 6*k*5qnustance of 50.0 m. What is the net work done on the eleva/kqrgn 5*:y6i*0gtsu4 qtx ma tor?

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 r+,k*pt7l7f cxi v8lvup 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,vs0 e7(q cn4-7gnklx sl:+q vo inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy surfao id8k/9.ak1 3o,bk o8wlnvn ice (assume no friction), with a force of 60.0 N 3v/o8 i,9okklai 1n.okbnw8d at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of thepkm54 j3t hc+z force. The graph in Fig. 6-1 shows the force versus the object's position. Find 35k t4+jhcpmzthe work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. kshxsm,2;(na- .p 3mubvceac((-0vz cyo j m -The graph in Fig. 6-1 shows thej-v (--ks (mcv ;m3. occmanh0(uaz,ex2byps force versus the object's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the ffmu w* 7ygtc56orce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from u*fmwt7y5 gc6 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. The2xm-ydyf f.-a 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 -xm2.-fd a yyfm.

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 200ewxdqzag:)oma9175 )v fmh -h N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface.mf-e: dwg) 1hxzo5mhqa7) a9v 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 x-1u56l u juand8)*qkxzce : lcart (initially at rest) across a 10 a8: k) dxqu6e*c -jnu15xl uzlm level surface. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a sp2-uwno *l z /o5kun*o)wax(fw eed of 5.0 m/s. How much work is required to stop the mass?nwlu w-wo/ fnka(*u*zo25x)o

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 1:y, ij4djd32 fmwc--ao dukg car initially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s ud3:mc4yj 2 if,-wogkadj1- udnder 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 darzyev 7pixl )42frh4 y.t. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mi)vlhf4 247yrpz yx .eass?

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 N and a verti9vn9xcpvphss e 1v 6t )c8a rh2q*0z6dcal component of 60 N. The*d1 62ac hvstzp)xqs8v hp06r99nce v force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along 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, e6 wsxrwl c;xf62h7v6striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. Wha7r66cv x f6lwsewh;2x t 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.v +b9 lnd,/+, xvhpgyu00 m above a floor to a height of 13.0 m above the floor. What is the change in gravyd+ux+ l,pv 9bn,gh/ vitational 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 4jm6jus7+xpjh9: v st- .0 m long and rises 2.0 m. If the plane is fricpux9mt: jssjj+ vh7- 6tionless, 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 3x f+bhhnv;wglhd 771 xuq)9t the spring to stretch 2.0 cm. What is the spring constant73 7wx l+un;1xv9t bhgf)hhdq?

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. Howtyb3e h09-+v0w7kgs ko-2x i hvh,b fj much potential energy does it store, when stretched by,b7-vhh o bx02k09j-h3 wsvk gy+tfe i 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 tumksgw2 4 62cvo compress an initially uncompressed spring with a spring cong6sm22wv4cu kstant of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N/m from x = 0.+ f swvb7x/g b67ag34v sa)pyo20 m to 0.25 m/) aag37gov4bs +7pfsxbw6y v? (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 1j tvrlv36s:beka 4n **5 N/m is initially compressed by 3.0 cm. How much work is required to compress t*b kjn36e4*:vr la vtshe 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 om xax 9w4dw.n. 2 psq*b6it8rnf a 50-m high slope. What is the speed of the slier on reaching the bottom of the slope? (Neglect friction.nbqw dx*w m2pxr4ia68..nst 9)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial speed of fntm a+s0zh-c;g 65*qcq-mh w 4.0 m/s. Neglefhzht +a;n5- *c0m- 6 gqqmcwscting friction, 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 inclined plane. At the bottom, it has a( cy ccjo 3nel:2v49vv speed of 9.80 m/s. Whatc3jveo 4 cvcv:l( ny29 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 f(t 5 serz: h,4sww,zealoor, its potential energy exactly equalez( a sz,5r ,t:4wehwss its kinetic energy. How 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, blasts straight up 2ywb mbrs/ +x6 vf uni91v,x7vfrom ground level with a kinetic energy of 40 J.xv6v7,1i r w x/2u+bynm9svfb 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 kinen.5,q dl*pot h8xs pg/y7ybg1 uyrl0nl2- t+wtic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, di5yny t1*l p,g2hbw/q8o7s x g0+.udrl n l-ytpd 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/bffz8 j06,/leg i,cyf vd,vp m above the bottom of a dip (See Fig. 6-2). ,gl,z jp,d ciff /6v/fe80vby Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at aw+p mgs,f 77yw 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 nmgsw7pw y7+,f ext slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip witv0 /urdu2h- pk 6t7joch a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at tc- 0rtk2p vd7uo/6u hjhe 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 the ball at the bottom of its kk(dgjf)7stzd 7;l +3 ka:d/kkiiaw7,e(fzx swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from the vertical axis ande) vsmbkg99y 84t5nf m released from rest. What will be its speed 495tg ) k8fvysmmbn9e 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 an5; q -pp qpml/ptpyh(0 initially uncompressed horizontal spring with spring constant of /hl (m;pytq p 5pq0pp-$2.0 \times 10^6 \; N/m$. 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 rede ri 995co n6swzt/xxp;g x09t 2+asyk light. What work is done by the friction force k x0xetco5y/pat 9ir69snsg;9x2z +w against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg objecm:ey0 4qpm am5t and a horizontal surface is 50.0 N. If the initial speed of the obqmy5a: mme4p 0ject 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 oniwncvd1axf ;j7 sd; z.e2ds:7 a rough, level surface. It has 24 J of kinetic energy. The friction force on it is dv2nsj ;xwe.c7d i da:z17sf; 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 on a level surface.ir8 y ytwhue y;(1fszk4 k. q7zrdn,27 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 isyrkk8zy;t,q1wz742fh7n rs( e.y d iu the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. d *:g mhh.jgl:.mgj m2ash)1z If the work done by frg:j ) da1gm. mg.*hhhm:z l2jsiction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed upobqdy ,y/v-sbi ye.1 u 0tx38e 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. ix,1 .q byvdy-t/0eu3eysbo8What 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 rolb xy:0gchs-f;4)x g7og4v h est 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 l h:)4cgyhov; fg -s o04bxxg7sliding 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 droppekegknh)ld )tm/m7q4u+kh8n o--2 k nr d from a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts ohk7grm)ln+k/n--4 odeqm28nk u) kh tn 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 enfj41l 0w qfbox.r:f/wergy when he runs up a flight of stairs 10.0-m high, lf14o 0/w: wjbq xf.frin
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 objec14tsf5 bcuv3x t with a constant velocity of 5.0 m/s. What power must be delivered to the object 3xstvb c4fu51 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 motor that runs for 1.0 hr?9hfcbqzkj/36z8 csr1 (1 hp = 746 Wzs 6jf81/ brz39kqch c)

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 ilnxi+.qhk9xuw;y6n :y5eej4t 1 xj+500 W while riding. How much force does her foot push with when she nu6q. iihtjx459 wnxy +xee lky:+j1; 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 0q s iiqlc7a5mw7,zy0 nv2h9x8 to 25 m/s in 7.0 s. What is the average power d0 9zi5yqmxvca7l 2s8,qi7h nwelivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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