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

1#

What is the correct b.r2fwto 0f+ bunit 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 systemy it(0*o8cwz w/r tpml cp2ax+d-68ck 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 stationary8 zik b3h8yx--bz :kwra2qa;v brick wall, the amount of work you d-8a-8v raz2 xih:bw;bkyq k z3o

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 much kt6imm8 )n) rlwork is being done in holding the box in tkn 68ml)mr )tihis 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 f*i+4o 51 gojj lkb)/;vshqqc at a constant velocity carrying a 10-N objo cgo/)jliv* +j4q5;fkbsqh1ect, 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 returned to its lx71bb,e9cu,1srf ey original position. If the total b9 yub,xce1s1l ,7erfweight 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 fo61qhjlte6kg;p5s zk qt;(e 0erce acting 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 h q ,jfb4zp+9f 8*1nsbbha83 mu58ilnchs2jtthe sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it 8fmlb98fhbn jht3z8ub2as c 5p4s+,i1 hn*qjgoes 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) grap bff34:dvg(v jh, represents bj:(fg 4d3vvf

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 p u16h4(-pr qs1mwr q 8r1x+w)cjx slptosition (F vs. x), what represents the work done by the forctwcwx- s)p4hr 8jqu6s1r(pmq+l1x 1 re F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

D. the product of the maximum force times the maximum x

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object's kinef.wgy 7gcmm3a0urn 36 tic 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 tbn 83cap0cr./;jrc k fhe 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 en :ev:hj;eknp6 ergy

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 3 idwuo-)g.h gch ), beg3jm6tmoving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of thehw c3o3u) bg )6j. eg,dig-mth 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 faste:prla(d rnaypd l768; -9 fxx as car K, and car J has half the mass of car K. The kinetic energy of car J, comp l(y8-l9rax prfd:76d n;e apxared 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 6/gh( m0g pm26+d zxb;dmkmr c /9ycufhalf of its original speed. What is the ratio of the final kinetic energy t6kxyd 0zp ggbf md(+m;2r/6 u9hc/mcmo 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 e.udhg71 s7u:bflq)mm/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic eneusb7 d :hef.gq71)mul rgy, 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 rway 5v9 -pcvapet.,8q/ n/bmwith speed 2.0 m/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 travelsve-5a.py /twc8,ap/9mq nbrv the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a cert)(a*vbo ,tsjj ain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the)aos(bjj vt,* 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 orbit. Neglecting anyn mx9gq xhe.+5 f+nm gx e.9hqx5riction effects, what happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

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

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principleqllp w736 mz;7ld2 qks.

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 syste;3zgwxn cz9 2ab54of ts:dm 8ym to have negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the ground. ,o+,bw:+nimd u* tgor A second object with four times the mass og :,on,rw++omu bt*dif 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 cp/e 10q;( ob3poxrcxf)ek/q gauses it to stretch 5.0 cm. If another 0.200-kg mass is added to the gece ;p 0/qq b1rx/ 3)o(xfpokspring, 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 of a sy uy-3ie 7 *e*qv3m-dkc7umaamstem

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to its potential ej bv8h9 p7y3kknergyb 3p kjkv7hy89 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 eu( * hv 8jaheyg3,+.kn *3yxeqbazf0of a 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 h-obm:9af7pb p5 vvcy( eavy object are sliding with equal speeds along a level frictionless surface. They both slide up(vv7bmp5y9 bao c-:pf 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 j1qqes0n5 4o1i-hjki$m_{1}$ 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 energy for conserv:v42 a,hcm zxts 6kxa;ative forces.ash am2 ; 6k:4c,xvztx

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 to82ko -77bvxj lso8hiap of a 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 energ87x8ok hjvl2 i7-bs oay (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Do not0 tqutr+e. harp alc12u2fl fchw9 u14a */x.a ignore air rc l+ w. 02aafu ruea9q2a. fp/x14rtlt1h uhc*esistance. 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 30iacs /dd. mv8c b-d:urm)/lnc 5;fq;o J of gravitational potential energy. Do not ignore aidl dc-bc./uq mamrv ;:of;/5 ic8sd) nr resistance. How 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 conservatioywqeqkym9+h/ r4 ; cgsi;o1yi7cm(h ;n 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 isrk+i(.,iv l h9dy yru:k :3qox

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 expressed in SI unel. 0x3 x(fvm lmcj5b9its?

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 power6g1 )dxlzotjby 3ujv 62 xc;1e?

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 o /rou9 sm6suww0 62wlcne-third the time. To do so, 96uss2wu r6o/ mwc0wlyour power output must have been

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, the car's engine musty9r e*swpw: h(jkd 88t

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 therb*ynq+qzl m+vk v--v7( 2clkze. If the object weighs 90 N, how much work was done in z2 l7qqzvb-k +y v+v*cn-l(kmlifting 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 of82eaxnf x jtji 1vxq/ki-4.r* 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of thex xrqa12f-.tix*v j8jki/4n e 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 for a b/ l rg-8gdml)distance of 50.0 m. What is the work done by the 5500 N forldm- /lrb8) ggce?

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 c)hyj+6l* dycih-dgp a 8qa wuw.s,//tonstant force of 5500 N for a distance of 50.0 m. What is the work done by the we6 gw/8 -utl ,chp.ad/yjswi+qy a)* hdight 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 ofv t,d q/ wi1f2tdk5*as 5500 N for a distance of 50.0 m. What is the nettqk sw i ,f*td1vd/52a work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up azk:m s+ gj l7w+: da1,kvz2xfklong 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 :td.;tw)urtyz7i ; ro 2:pyg z8.0 m down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy -( l 6bzuoeu9w b 6bv*llg6nxcyrp,.3 surface (assume no friction), with a fo6nupbclbv( l9oyxrl g w6,z.e*u-63 brce 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 objf/wf g k- rn+v9 iq,lop/tq chz19:u-qect in the direction of the force. The graph in Fig. 6-1 shows the foq9kznqtq:9wu-l -h,orfgipv +1c/ f/ rce versus the object's position. Find the 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 dirvr cq,uj48thokrsw63w, .c b .ection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the objeww.6 c . hr j4qok,sc3br8tu,vct 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 foryof,jn5 r(ea65e- y fu 8oz+8cj, gtowce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 4.0 to 6.0,5(jyzg,88e o+ren oc fy-aftw 5 u6oj 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 in Fim33 wy* f 1lwe,rq7zdehyq2*hg. 6-1 shows the force versus the object's position. Findzw7f w d3r*me12leqhqyh3,* y the work 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 applied to move a 55-kg cart (initially at 1ks)aw b.j2tz xm+o8fsqlk0v; 6t2c 4lxe vn,rest) across a 10 m level surface. What is the final kinetic energy of the ca v s, 8exvafnsk124;j+ mt w2btkl6)c.qx ozl0rt?

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 appli +bof l9bufpu.5ls :u,ed to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the p,u.b:f +ufl l5so9u bfinal 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 requiredwshsbqw1+vs2y-i.1 g to stop the may1hq-w2 1sswib +v.sgss?

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, whayg-mu p)fk u78t distance is required to stop a car moving at 5f kg8)-upy7um 0 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 /uh mkg/qj dwhz:y(95a 10-g dart. It is cocked by exerting a force of 20(/jd9m5 hyuh zwk:/ qg N over a distance 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 N and a vertical component ofl yz:.+y 0txtt 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 horizontally along the flooy0. t+ylztx t:r. 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 horizontaz sbf7l0 jto+ 9byp;u9lly into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm be7+p yjb9;9 lbo0tu fszfore 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 ofz4bwj) r*rcqm b1r.- u 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitatiqb1w. u)4m-* rbj zcrronal 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. The59.pa7a ahlnine-7.h o1fa6hsq: w gv plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how mu9.6hafh -gv: einas7al qo5a7w 1.hnpch work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to stretch 2.0 cm/f ooll( 1vodbk7k uhr )44,lovy8u,o. What is the spring constant7r)v ub1/8okvoh l ko y,o(flou44d ,l?

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 mtsohqp-ld ib5l 8/ a9ws6 hz9*uch potential energy does it store, when strltz9/h a5wq86lipsh*-dosb 9 etched by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed springto0lmi1s :,cq with a spring ci1l, qc:o0s tmonstant 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 vuuvk. 8u,ia /pn* qs-spring constant 40 N/m from x = 0.20 m to 0.25 m? (A,/*u-us.vu iapqv 8k nssume 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 c 2 wdid.s-(q3 4sblipvompressed by 3.0 cm. How much work is required to compress the spring an additional 4.2d (dqs lw.3iv-p4s bi0 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 sldv dgl h5lh.pk8e+7jaj 3zy9 .ope. What is the speed of the skier on reaching the bottom of the 5..pak+8 yll he3djv7 h 9jdgzslope? (neglect friction)

A. 22 m/s

B. 31 m/s

C. 38 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off thr bx ce *g/bc(njz/(hxiu(k26 e top of a hill with an initial speed of 4.0 m/s. Neglecting friction hgbz/*(r(ixkx2ebjcc ( /6un, 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 bottc54p +srr+dj vbf; yk1om, it has a speevf 1; 4+rjdpb5ysrc k+d 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 the floor. When it is 0.70 m above the floor, ipjtt69 kcq 4x,0v oztv-z;4 kxts potential energy exactly equals its kinetic o; 9kkcvxtz ,-pxtqv64z4t0j 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 from ground level with a kisnkajc /v40 y8nor;m1netic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To wh;cjs o0/yva41nmk r8nat 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 lehc mv54kpp zs *r.)z)aaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. ) z .5kspa4c rv*zhpm)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 poim5;nji ss4hc:rvkuqrq+-kjl k 0 75 r/nt 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, w5: h0vqn/kirsk4j;cl-q u+ 5rsk7 rmjhat 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 poink odgp f/ 1wue)5tlhzg8z1a/7t 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be th gzf/wo pt5zka)1 lh1dug7e/8e 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 3vw1 y) vl)faj-) .mjbt0 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m abowaj.yvlbvt)j f)m 1-)ve 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 swing (poina2,thkn7lo 4 r*jx( plt

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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 0.19 m away from them6n32br d2 oodvp a.kygq8z6. vertical axis and released from rest. What wid6rv2a.np86k g2 .omybo3zqdll be its speed at the bottom of its swing?

A. 0.257 m/s

B. 0.686 m/s

C. 1.03 m/s

D. 0.857 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed hori* : lsqsaawyqqq.pt:v88 (ed,zontal spring with spring col., 88qqd(ts q vsaw: qa:*eypnstant 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 redp i+p drp:y a5s.w29ej light. What work is done by the fr .9 irepj5w2dy:ap+psiction 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 ob4sanj1:.eql ka)3(x jee1bhxj0 q24iinrhj :ject and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what dis 2r(h khjq i3e enq:ix1ebn)j. j0xs a1jl4:4atance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J of kinetic eneru dv,kpq8b e55gy. The friction force on it is a constant 0.50 N. How far will it slide? pbq 5u85e,dvk

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 ev(ni; )jba 9(yl-enjsurface. The coefficient of kinetic fri(enj)jnia- y 9lb(;vection between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of ay,mo-asdyg // 50-m high slope. If the work done by fric oy,-dm /gys/ation is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane:rqm9ad9/ zs tx. qgw(. 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 force on theq9az(d.g9m xt/rq:s w 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 of a plane inclined at 2ls p7l(kvxkj99.2mq l2p sj:*rjzb2b0e above horizontal. The cq2j :xkpj *r2bbj7smzl9 kllv(9.2spoefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a he::d; ueqvstyop 9ttpk) +9( d5 zac6keight of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. stkud a 9c6ky 9::5p)e(ztovd qt;p+eWhat 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 boyn3) ekdmms):tl c0e n. using energy when he runs up a flight of stairs 10.0-m hmkstn:ee0)m.ln 3)dc 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 ob()8g omzy3su zject with a constant velocity of 5.0 m/s. What power must be delivered to the obje)osu zz38yg m(ct 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 b9)l,iv)orrpg:o 1j ; u6fqqv1.0 hp motor that runs for 1.0 hr? (1 hp = 746 Wqrq;)bjo ,6vfrgoi)v l :91pu)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while ridin18fj 7mtxgx:f1y o )nkg. How much force does her foot pft: j g17nfm81yxk)xoush with when she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is the avehj.otrl db, -yoc:p0(rage power delivered d:.,b-tpc oy o(j0lh rby the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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