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

1#

What is the correct unit 3jdihc2n)tusa d+:q; of work expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there isa-audut2*w)s0vpti*r rcx * ) wnsc5/ 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 d;(5 2a.uls ne hgo k4yyyv+s3wall, the amount of work youe 3.(ynh ukl s4o+5dgvs yy;a2 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 held there. How muyam/l7xtl .oio*4 (ap.ckaj, ch work is being done in holdin/aa(l, o.l7 4ma xck*potj. iyg 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 veloc / x;g tbcau,vkj*y6/uity carrying a 10-N object, the amount of work you v uy/;xc/ua6 gtj*kb, 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 returned to its original pot o46 i2*a a,lp8yhvzrsition. If the total weight is 30 N, how mucp8a to,yzr4*62h iavlh work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the obz(0(mi d 9h;ay:woxhoject?

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 of the work done by gravity ecw x+m6zsscz :l9h0/ku8vzqpz27 k2while the bam 6sl9zc +8h27xzwq0suc pk ez/zv:k2 ll 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 Forc axi yr)o1 etv0s4+2fxe versus position (F vs. x) graph, representsoe+ iat x04)21vxr yfs

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 repr*wbexs. lzqa ve c3ylc)n(. (.esents the work done by thx.l*zcq b(esycv n).3e.l( awe 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, ok1g nh. vt6vv(ir( i/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, then the object's kinetic energ o7afxg(fv*e0y

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 od sjj6 ttj,0j*bject is zero, then 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 zd.l4ibc7im v ywq.*6r.4z vpas a car, and is moving at twice the speed of the car. Which statement is.p*6b wzmv7zc.ivdl iy4 qr4. 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 hashfw8 di*k9vm. half the mass of car K. The kinetic energy of car J, compared to car 9. hkif8dw*vmK 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+6ye0btz r+ ea of its original speed. What is the r+ be+0ey6zat 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 pebbqa-qptlf3mf-s* 73 lzle is moving at a speed of 5 m/s. If both objects h-3t3 lmflz7pfs*-qqaave 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 speed 2.0 mc4y6nr o* y7vj/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the yoj4rv7 * c6nygreater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a certaine0oe xrek6zoy .,iu7-1uh/8 u h1oqjn distance on a straight, level road. If you had been traveling twice as fast, what distance weoy-e0hquz7j/ 8 6xuo1ro 1,iu.enh kould 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 the Sun in an elliptical6o9;or2f7 ue :v kwyil1 )lcfw orbit. Neglecting any friction effects, what happens to th1l:6 9kur eo )o7fcf y2wlw;vie 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 principle.16+mb1 da e5 )nuvbdwx

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 enerp 3 52bgzgz6zz0q ixf0gy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. A sbh2ja-5* 2mb- uia pl*csd(zcecond object with four times the *b(cp lmz* d s5ai2chu-j2ba- mass of the first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causesigzkss;hxhlm4 h3l f,/ 4aw55 it to stretch 5.0 cm. If another 0.200-kg mass ,a4lmg5xhhlfws4 5z/ 3ish;k 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 ogbw:, mpwp+) wf 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 its7wmlq6 7* fuft kinetic energy K, to its potential energy U.7 *6qltu fm7wf

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--j / fkfwc1ch car driving 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 slidzlek 7g,5y9nt ing with equal speeds along a level frictionless surface. They both slide up the same frictionless hiz e,7gn 95ktylll. 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 em2, teiu rf4n v0kj(0w8 sj7h$m_{1}$ 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 energhfnqsq :*r/iii-i; g-y for conservative forces.in;ig s*fi-q: rqh i/-

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 frimrtbr+uy l2rdc44vdi;.v(*w+yy h h4ction is present), to the ground below. How does the kinetic energy (K) j4 vyurv; ldmhrc(yy24hd* +w+i.tb4r ust 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 gajl8 i;n 4d crk 67bcw.fbt00hmins 30 J of kinetic energy. Do not ignore air resistance.b;l r.n w7d40 jhmcf06ti8bkc 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 loses 30 J of gravitational potential energ tk2o26t79uz:elz0ct i-m pbyy. Do not ignore air resistance. Howzut -06k2leot2 7t cz byim9p: 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 conserv+:0tygvic*6./ e +twoyzlxi vation 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 ismd2bi4x m5pm7

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 poaf9)nti+ark4 cu-uw 3 wer expressed in SI units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit of pj)iq( j:c* doyv4xh07n;dvm iower?

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 ,u/fld(ohgh( 3 times the work in one-third the time. To do so, your power output must have(,uh(/d g olhf 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 cad qbc;z **ae;yuw 3p:pr at a 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 ogfil8i13z2 e vgs* l*6dk 9xafbject weighs 90 N, how much wi2f9lvxg l8 1a*36s*e d ifgzkork was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at a c 52p*cei8vf b9ngn c9wonstant veloce5fp8wi*2cn c b v9ng9ity of 0.50 m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant g6xlzq)vqj)9 *rzkevkn4 i/ *force of 5500 N for a distance of 50.0 m. What is g qvljke6 v *qk)zi4x9)rn*z/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 a constant force of 55zwx)x nl.6/7/xgw7eu .b a8wg.1 xm pha2sqcv00 N for a distance of 50.0 m. What is th7xcxx.w 6ew7)/a. 8sg1 nmgbp z.lhuw2a/q xve 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 upm h0hn 2qvyo0;ward with a constant force of 5500 N for a distance of 50.0 m. What is the net work v h hoq2n;0y0mdone on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up a)eoql -to b(k1long 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 dowf03 :ixj m x0dchk 8n:z:3rsdpn a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on azdjj i;qmtv ht :2h03 83/dapen icy surface (assume no friction), with aj t8a; h:23mjdt/z3p vq eihd0 force of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. T8a r )y0dwby5/k ubg,ehe graph in Fig. 6-1 shows the force versus the object's position. Find the workuk08)wyy, rde5a bbg / 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. The graph in Fao9rjw ,4phw2z(a 3u jig. 6-1 shows the force versus the object's position. Find th(z9h,aouaj4r 23wj w pe 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 i:rz ,ndiy ,r4d.n:jldirection of the force. The graph in Fig. 6-1 shows the force versus the object's p4ynrij d:l rz.di,:n,osition. 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 directiolx 6*xh5yd rmn/e7(xq n of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to5xl7n*qmdrx xh 6y/(e 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initial 6utft er20pyxjp5(5bly at rest) across a 10 m level surface. What is the f 5f0e56(tjr t2b uppxyinal 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 movb;0n .o8w reete a 55-kg cart (initially at rest) across tbw8re.n;e0o a 10 m 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 speed of 5.0 m/s. How much work is t z+:.hf wo3uorequired to stop the mass?uf+.tz :oo3w h

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what distance w6qq/ pfgx d9k8zd s, ayd7a;otwky+ *j 65s5iis required to stop +z5*,add6pof y s9wk digaj;s5t8 q7/6yxkwqa 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 cocked by exerting a forco5aotrpt,): dk gr*bs: ey-/b e of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assumpok/ytd - srbb*e5ta :)ogr,:ing 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 N and a vertical cov 5shinuo a 002(pvz4jmponent 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 horizoihn jo (vz2 vpa0504usntally 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 horizontally6ty8js(7niw ujyo 3f4 into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the ar 7yjuw3so 48t(fn 6yjirow?

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 height o e6 rg(apmk d6)c(bp5bf 13.0 m above the floor.(ba(6 kdr)5 gp6epm bc 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 plan:da.o cr d( wt2iup:i, j: h4jya0oca92rv4c ae. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much work was done byadcr2aj(iph4d: 0c4y: au2woj, :c9 ao trvi. 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 thw(pt6(gm uh krc4 +2b6dgsz)2izb3ite spring to stretch 2.0 cm. What is t kd+u(bgw(t s3 2pbg6z4cr 6)mzi2ih the spring 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 potee, h n/eczy*c e7icc octs;.-+ntial energy does it store, when stretched by 1.0 cm?/7-e.cetcno csec+*hiz; c, y

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially .ewi(vb 5)wuada45axs0n. zjuncompressed spring with a spring constant of 25( ib5uax..0sa4 zvwjea dw)n 5 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 constan : rg/o+vyc 7rbfq/l ,o)jyp b; yupq,je7yu-4t 40 N/m from x = 0.20 m to j:you/f7l ;g yqo4berr,yj )/ vp-,uy bq7+cp0.25 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 m*(lbk0qpe49spw f 5l/njri*x1g j -d3.0 cm. How much work is required to compress the spri9p/ r4l (s kxnwfeg0*pbm j i51lqd-j*ng 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 50-8,lpbzsg, kw,5r9 ks 0dl zd(dm high slope. What is the sp,0z,k( gs8blkdd rz ,lw5ps d9eed of the skier on reaching the bottom of the slope? (neglect friction)

A. 22 m/s

B. 31 m/s

C. 38 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushedead j jiw)g 0sa+7 9dx k7n* v+4tz6tjk/4tyxs off the top of a hill with an initial speed of 4.0 m/s. Neglecting frictiont476dw)9ak7 0t/vd yjsd jx+gx k+j*niatez4, 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 s5 g/uy-js mrlz./ nrn8peed of 9.80 m/s. What is the vz.rn8ugm l/n 5rj-y/ sertical 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 03zip b 6;rw8 bx*-pjql.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast isp 6xq38ibpjz lw b*-r; 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 from ground level with a kineticsg6uc o4k;4i b energy of 40 J. At the exact tk csio;b64 gu4op 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 energy of 22dbchw;20 - aa8i wyp.gnsp14 b0 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point- yg4i p w pb.a2b1nwh;a80dsc, 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 bq aopv8ri1 of/p- y3z3 2rs6leottom 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 thez pq36 ryr1/svai2o 8p-3eo fl 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 above the a ma.4jzqf k9bh,2,og bottom of a dip (See Fig. 6-2). Neglect fricti ,,f9jmg4azhq2.okb aon, 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. 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 we24yw( h srwru: 5hk,vith a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the s,r2:hrh vk45swwe(yu peed 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 ta5zyf 9e qhc40(avx ,oh* yoo1he 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 0.11 m away from the* ipunxm9ilus3k 9ld 9e)e.-lv+e0 km vertical axis and released from rest. What will be its u.3u nkv)9ldl0l ime9 k msiee-p*9x+speed at the bottom of its swing?

A. 0.147 m/s

B. 0.392 m/s

C. 0.588 m/s

D. 0.49 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 uncombf/g+2yi0)h,eglx fk pressed horizontal spring with spfy+gbl)/,i ekfhg 2 x0ring 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 *pofbp vz9c br7wikj-93g ( t(22 m/s, slows down her 2000 kg car to stop for a red light-bv fw7p ri (b3j(zto9gp 9*ck. What work is done by the friction force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a7 jvve,:y5xdy 0vyzrhi bn:4 k(p1tx9 horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a sto t ,:vyxi ehrkdv091:jbxyp( 54v7 nyzp?

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 movzh hxb (h;v-ur5;2 6agq buti;ing on a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far 2g5 ;uiu6vr -;thzahbq;x(bh 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 horizon q,mu*6n-as1d t )goeutally to a 2.0-kg mass on a level surface. The coefficient 1dq6aes,*gtnu)mo-u of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest fru54tetbyc z0uh0 e )jkkk x,2)a8u r1rom the top of a 50-m high slope. If the work done by frictitk ar5y c8e4),uz0h)2 j kxuektrbu01on 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 up5 ;ktzqmq fu vjfws p(u25rg7 ).y)-mp 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 magnitude of the average friction u-p75q )(m 5sujptzqg;rw. vy)fm2k fforce 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 top. c c:ps*;4lzr6 yzwgtb4 lkb1 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 o1. *t6bl44 yc gz:ks;zprlb cwf 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, .r+-yt kw1 wcb t+oh4v; xlz5qand strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it aswh 4kox-.zqt+cr1l+ bv5w yt; 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 runssbjk i3o/75 6xe s2fgk up a flight of stairs 10.0-m high,si kok6/f s3jg725exb 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 tz0:s dm9q ;/bel 6zfljo move an object with a constant velocity of 5.0 m/s. What power must be delivered tm jd9:6ll;ze0fzs / bqo the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs for 1.0 hrah+0y n.m 6b-n0cw,l) o2uaqc8 etcrr? (1 hp = 7-n ,wc+l2) tq8 .cme ou0r bayrhca0n646 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 atyn:sr h8w+;ry(2ak ln the rate of 500 W while riding. How much force does her foot push with when she is traveling :8k2srhwl ynr a+(yn ;at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is5cd a+ad4o *e3es(fa j the average power delivered by to *ad43ea efs(cd+ja5he engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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