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

1#

What is the correct unit of work expressed w,y1x /2)x /79oiwz9(owkfhwyoys tuin SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no mot8dj+g 74h+d qakv mg/dion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the amount of worpev:: 2p9kt 4 oxh9iknk you dp9tk:vk 4p9e: x oihn2o

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 gjr0hu5zm .) b4d/fvw m vertically and is being held there. How much work is being done in holding the box in this positiobfz/.gmwhv5 r )4 0dujn?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constant velocity carrying a 102t xs3l ; da,w8.uzefx-N object, the amoun 8uw;lde3xas., 2x tzft 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 verttuz *y v+l i7,ra6aa3wnttj/1 ically 3.0 m then returned to its original position. If the total weight is 30 N, how muttar6uaj3 t7/wz1,a l*i+ynvch 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 wnvurbo.8o 7xo8w(q 4d ork on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball str-g5r/g y)p apuaight up. Compare the sign of the work done by gravity while the ba/p -5prg ygua)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 Force versuses wona)o-yo0)b1 h 5i position (F vs. x) graph, represents-sa50yo ni1h) )wobeo

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the work do. 0if,sp0heuone by the force f0h.es u0oi,pF?

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 kinetic .b8qegr a d+:w3r .ajbenergy

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 objeczxyof60v.l8)4jyrv g t is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on,j62r6(ivny,2d q)rrgyas j ubd4w4h an object 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 as a car, and is moving at twice t;)(3)gvck4avyxem pma 6, ljc he speed of the car. Which statement is true about the truck' kaajgmp vly3xe(c6,)c) 4mv;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, and3lwqi fuh6v n/0f5fh 1 car J has half the mass of car K. The kinetic energy of car J, compared to 1nvqih f /hfw5 ul63f0car 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. zedn(u q6uzx4rv7 )p5What is the ratio of the final k nduvxuz(eq5p 476)zrinetic 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 0e5f, eheq ns(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 thee(5 f0ee,nsq h 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 witmm qu5 d+ozw:;h 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 m+udmq;wz:o 5rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a certain distanja7 bs; ylxh./ce on a straight, level road. If you had been traveling twice as fast, what dis 7bj/ly.a; hxstance 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 the Sun in an elliptical orbit.du* 9w(nf/fz(otr p i4 Neglecting any friction effects, what4f/* d(t9orwz i upn(f 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 principil2 bk3 l,va+sle.

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 afqvx58+6t2a/ ad rr fq system 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) .e0 jnn0t i2vkaw0diuu1*turnz);i . A second object with four times the mass of the first if released from the same heigh t0za *j0k2)iiwed ) nu0nurtu1v.ni;t. 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*+gzqvi sn ghf7rc/(knbzdx 6x72y6) spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring will xy xf6c)67q*hgb /+dkz 2ni g7(n rzsvbe

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 l,+-x: xn lgpm)zha3dof a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kie,ykqxhn;+:yb bsf n2:;5 iz5 c/bdxn netic energy K, to its potential energd ;:e n;b+2in:y,yz 5s qb5nxb/kxfhcy U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving up a hil k*pcj3h9twt/*k5jg xl.

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 qyr9bj10dmo+ xe ebgj41, r( pobject are sliding with equal speeds along a level frictionless surface. They both slide up the sa0ybj(remo9bg 1 4r+1d,xjq ep me 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 6l+use0tk4 )u*yc f w a,;gayl$m_{1}$ 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 co*fao c5tttgw+i ,u)vspb,22n nservation of mechanical energy for conservative forcessw+tb f*tnu2)aocp2 g5 ,vi ,t.

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 b9. w t u/:k9upnrfa8n6/gdzx 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 wb.u6/png 989u:k tnzf/arx dof 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.momik7z-m 8) q Do not ignore air resistance)k7qmzmmo-8 i . 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 potw12f fai*,8 abj ; raj*wkmgn5ential energy. Do not ikjm *wwi2g1ra,b;nff 5aj*8a gnore air 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 conservation 6r7 hy*irgs wygnfe+j2xd963ue)( m c 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 is3o/j 78mcgp:v j9jagg

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 exp*fkp 6usg(+51m,w tnfnvn; qi ressed 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 power? o6ctk5e:jjva/9j ofbi r1b;:

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+g1rcug;; howbl64eb hdn8w 9, you did 3 times the work in one-third the time. To do so, yr8ul9g h 1hww ge6on4;b;c+dbour 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 q7up0e( i0l2 3uivjyhmust

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 vertidwfgp29v f+/b- okrx-cally 2.0 m and held there. If the object weighs 90 N, how much work was done in lifting itx-k9r2 /ff-gw o+d pbv?

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 conjb8buyji*;omc 1y3* tt+h(vj rt7n)jstant velocity of 0.50 m/s. What is the work dontjbjy*iv +(y;u8)tn c7ro*j3mh t1b je 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 fz suo ,glho;4:or a distance of 50.0 m. What is the work done by the 5500g ,z4o:o;uh ls 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 pulledci-1 m+n v6vias9o5 w* fjut9j upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight ofw-iusjovcmat i+*j 19v9n65 f 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 upwardep q4g q*8pgz, with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the eqz8q ,p*gg4p 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))- alf8k6 n,v rmfea6nj tycu 5esxhkcd 8.0/ up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit ku;t xpibsjjmms hu25b,zs 17n,7zfw8 37i x, slides 8.0 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 c-1w hjmw.(ly sister Sarah in a sled on an icy surface (assume no frictionml-jhw( .1wc y), with a 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. The graph in Fig. 6-1 s:*mka9+b c cskhows the force versus the object's position. Find the work done whensc+k b :c9mk*a 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 Fs,m.d 5bxe1 iautme5 x/n0dr4 ig. 6-1 shows the force versus the object's position. Find the work done e5x4atu. xdne 5r0/ dmm,bis1when 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 dir6;2c2a zj8b rt/uo phgection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the objecbo g az2jh8; p2urt6/ct moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of th0u 9djzba ;8jcrd o63ze force. The graph in Fig. 6-1 shows the force versus the object'b zr8 uz6dod a30c;jj9s position. Find 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 3m5urb:q3hmv*6wa m c cart (initially at rest) across a 10 m level surface. What is the finamm3rv:w*abc h5 q3u6ml 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 55-6fq- q)cvbau ye81itctkbd.6u 5v8*l kg cart (initially at rest) across a 10 m level surface. What is the final*qtad1 -tv86vqe)y 8bufc.u6blc k5i 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 8qcgpm w7wugq0n.2 h1much work is required to stop thnwqcg10ghq8 w p.m72ue mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moiei 4x a 4 *wedz),h 8kbx5oajdi69: ,lxzke5gving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same conditiaiez5,*i 5 ,kd8x6b)a 4od9zxeewj: gx lkh4ion?

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 pr ys xi/nh r1817v6dbjx6pz(dart. 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 sp/bdsh r167p yrv(1ji 86xxpznring 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 coz)o6fobg1kc+pfv) , 9s bfv, rmponent 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 horizontally along the floor. What is the cart's final p , v6bkf1),sboc9orvffg)+zkinetic 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, striku,71oq kjw0) zbsr-p kt72yrl ing the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force actiyzkr7j-qt ks1b7o u 2p), l0rwng on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to a heigw(zt d mdn94m4+or 9ktht of 13.0 m above the f(t4od9m4dt +w kmrz 9nloor. 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 incequw/t 9o8 ha8u)q oq sk.o0t9uba5s6lined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless,s.u0o/o 5b6to qs98teaq8u)ah9k quw how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to str8+ 5+; opvieeo4bq howetch 2.0 cm. What is t;+i5ph4 ev 8o+obqoewhe 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 oytbqr6dt, 777p vdix5f 60 N/m. How much potential energy does it store, when stretched dyqb 5 ,6p7x7r itdvt7by 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 spriv ,0xkkk uj/6bng with a spring constant of 25 N/m by 10, /6k0 kkvbjxu 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 fromm 8hxve)4 asuuq;g9 6n x = 0.20 m to 0.25 m? (Assume the unstretched position n4;a m8su6guq)9 ev hxis at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3.0 cm mn8fa7tnerbh.:zquh1f 2iq 0nji:7,. How much work is required to compress the spring an ad,i7e qanf8fnb. hhjqu72:int1 zr0m: ditional 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 tor4b kn f:7th6up of a 50-m high slope. What is the speed of the slier on reaching the bottom of the slopf:7t6bh 4urkne? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg*36y6 k z nbnaj++6y csbn+ocq, pushes off the top of a hill with an initial speed of 4.0 m/s. Neglectin+s bzy c 36+aj6q+6onkncn*y bg 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 incsxsc + wi,y+pg 5q-mi3d0q2xhlined plane. At the bottom, it has a speed of 9.80 m/s. What is the verticapyix0 is+ cq g,h-5+mwsdq x23l 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,m+p;:cb4s kvbps xz s ;)6jah7 its potential energy exactly equals its kinx 4am:j+;s p6k ; s)cv7hzbbpsetic 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 fro jl73a0rp 7lxzm ground level with a kinetic energy of 40 J. At the exact lr3j p7za 07lxtop 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 energpr)sk ;07c9 l jvfw7jwgu9q (my of 220 J. At the highe(f)u;7srw9j w0kc9 pv jmgq l7st point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a yw5swuj./qq 3 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 thw/ q3j5uw.qsy e 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 g0t(5n ,p 8peazt; cova speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Net ena,( 8p0gztcp 5ov;glect 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. 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 withn2vbs te 321mf/hm kx; 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 above the bottmfxv2s t;bk3/ 2e1hnmom 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 ota. ,-sws;0hxb) /hnmjc7 yx pe4pgo,f its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and reltcsgf:v9h 0 ;j 8zvfk;/k ;tc pisj7x:eased from rest. What will be its speed at the bottom of hp;f8; izc vk vgjj07tc9t/x;:k s :sfits swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed horizontalk x9wp5yuo4ujc t6,l 7zn8-il spring with spring coypwi8j4 tkcxu7n5-lo,lu6 9 znstant 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 bt1h a(bvb*p + l.zwj7to stop for a red light. What work is done by the friction force agal1tbvj bhb7+ (wp*.zainst 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 9e2ni+exp o7c lf91gp and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slig cep29opi 1f9n 7elx+de 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 kr5 es00b/v8v-t*90vdk etazm4vdady 2 djwv 8inetic energy. The friction force on it is a constant 0.50 N. How far will it slide? 5dbesw 0vaek 9dv2d*vt0azvt m-r 84vy 0j/8d

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 horizontall fkiafzvh :87jfvsp5n. 1my95 y to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 108 pfvmks:y. j7zi595 v1afnhf 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 a 50-m high slope. If the work x;5oxn0l-wosmm /z 9gdone by frin9z glw oxom;/x5s0-m ction 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 up an inclined plane. The plane is 4.o exnsy k f:/55,0fnvm0 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 averagnv:55skfyf me/x0, one friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined at 20e above (0 ztqoo,pb3e*1 bseg horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. 3pe, b01g q*z soo(ebt What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and strikes thwl;itmb (f17b e ground with a velocity of 7.00 m/s. What average force of air friction acts on it as it fallwb(lm7i; 1f tbs?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a fligp tcwl-a40yw *ht of stairs 10.0-m high, in *-cyat04pw wl
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constantmqym .q 4f5.x-m2pp ra velocity of 5.0 m/s. What power must be d qy. -24f.mmmpr ax5qpelivered to 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 foj4x*3 .gn,ska pd23z7a9 kilvgod8 fsr 1.0 hr? (1 hp*,4 d ovd 8jxksafgs97lz 3p3in2.akg = 746 W)

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

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

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

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while 4q4f v)jawnw9zjawu zg8 5u..x8y( y criding. How much force does her foot push wiyj89w (fzxw .4a z5vnag8)q.y wuj4ucth 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 fr-;+7wan3ken rg mh f/oom 0 to 25 m/s in 7.0 s. What is the average power delivered7rw- k;aof+ mng3/neh by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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