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

1#

What is the correct unit p,8tc4n hhww;of work expressed in SI units?

A.

k g m / s^{2}

B.

k g m^{2} / s

C.

k g m^{2} / s^{2}

D.

k g^{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 imi)uvk68;xi*qa3agx 6+m m m if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

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

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

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the amount o s i4aq(x 7gwxc8xk g38epq1fb8lf/w,f work you ligafgx q b c p1w8s4kf,wexx(73 8/q8do

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 th 5b6u7uh.gv/h /behkzxd ku): ere. How much work is being khg6 u7:/bh zu5)ubev/x dk. hdone in holding the box in this position?

A. more than 100 J

B. 100 J

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

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constant veloc :urfc+ vqpn16u lsz;;ity carrying a 10-N object, thq6c f+1z:vpl u;snr u;e 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 ,syd4rn9yio -m then returned to its original posit nrd,-io94yys ion. If the total weight is 30 N, how much work was done?

A.

45 J

B.

90 J

C.

180 J

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the7*ito(4tc - hi /ay6(lnh0 l-lgautrz object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign of 6ka26 :k +d 5nvia:v +oc bv/szrdqz1fthe work done by gravity while fdb z6 5a/vv6+kvc 12:zqaorsid:kn +the ball goes up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve,+fr* m5lah /ps on a Force versus position (F vs. x) graph, represents*h/ pflasrm 5+

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 versun1u19pg17 dderah.ec s position (F vs. x), what represents the work done by the 1hdru1p.eecg1 ad97 n 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} m v^{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 o z.uoy2 j ebf w;mn8k 7u:uqueixg(1*)bject is positive, 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 ob/ms7szig;s+ykp 2/qei / sac/ject is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, then the or1hci8s*vc uy7 tw,ds0 z5 .msbject'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 an )wl m*mp0+qt5hl sab* w ph77g1+sugs much as a car, and is moving at twice the speed of the cawm 5h lw*sbsn 7ap)0pggu+th+l17*qm r. Which statement is true about the truck's kinetic energy compared to that of the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of3kinsr qt7 od2 ljg0o04l); wi car K. The kinetic energy of car J, compared to car K r)4 3toglwk7jd0;qos2lni0i 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 halr-b6eir6rfpk) q+dd/3idr5a f of its original speed. What is the ratio of the final kinetic energy to the ddik5 db6 6)rfqr e-+rpi ra/3initial 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 pebble is moving at a speed of 5tnb312 (s hrfg0foz:dg4 u (tw m/s. If both objects have the same k (s(b:fthgrwz234d gt1o0n fuinetic 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 2.0lw p (k ng9qgsmn-g -pk.p *4)ou+(twq 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 browgpt o4(psgp+ kk*(ln nmq9. ) w--qugught to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of yv1by+k3 992j smltjmqour car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fas sjvky32b9mm1+ tlj9qt, what distance would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elliptical o jm p.8qmx luz,7g0xa2rbit. Neglecting any friction effects, what happens to the zuq p207glj8a,m x.xm 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 n 0xbjiye 91cp2l.u:l principle.

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} k x^{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 negati *lmu*yv+h9 m ztpgho /9ok04ive 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 /vh+ g+hzu2mcg tn8-al 5i +zohot5ljnl* 40yrest a height h above the ground. A second object with four times the m g c8t uhn 5va h-4*+ozt 2igzyl+l0hm5/+olnjass 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 causes it to strzap*20zg(bktg: v w ;retch 5.0 cm. If another 0.200-kg mass is added to the spring, the poten2gwatgbk*v0; pz r:z(tial 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 oj 7psjt y*08oxf 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 kinetic energy;)jsvhf;q nx*ks cy67 K, to its potential energy U.;j6snyx*q )kh sv7cf ;

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 drivingd4 8;;3itihrrj5 xwr x 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 object3 yjw3w (4awv3c3v pxq are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises 4 3v3 p3( q3vwayjxwwcto 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 3k2 nalsi ra*;/tudb -

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 mechanicwaxw9,s2mfq/ku n ,2iit ,27xi+ebyu al energy for conservative forcesifw9y 7iin2xsw ,,2e2, a/umbtkqu +x.

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 buildza)xsci b(97sm-8 jpc ing, 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 pot cjs7cp(s98a- zxbim) ential 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 9a9ymlhv/ixv0+(mmz gains 30 J of kinetic energy. Do not ignore air resistance. How muchav/ (m09 xh9mvly+mzi 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 grav uu/j+56uikl ie7lwe)itational potential energy. Do not ignore air resistance. How much kinetic energy did tuuujl) i l5ee7ki+6w /he ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation of energy.ui awe9p7te la:01ge-

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is j54api/ netv,

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 i:fusgcabq+0l )xub9 h *)ph+h n SI units?

A.

k g m / s^{2}

B.

k g m^{2} / s^{2}

C.

k g m^{2} / s^{3}

D.

k g^{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, wh q4 3oc9y8q+ieyut+fsich is not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the time. To d xdskhm5+rr)7l) bly 8o so, your power outy7 lb)8d klr sh5x+rm)put must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your ca* m1 jsonerzp9 i9v-/zr 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 object weighs 901onft z 3/abt( N, how mun /b( f3toatz1ch work 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 *2gz8va8 mwge9(ywn la distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of8 ww2elzyg8vm9 * ng(a 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 withknpv1sp s)q3 -qe e 5ma/*dv2qpgrgs,1r0o :l a constant force of 5500 N for a distance of 50.0p2)vgnsrgkq1/03ospq:vmrs 5*ql,1e d- pae m. What is 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 5500 N for a disu pebpw9ol5t*yc62 m p*w 3s*rtance of 50.0 m. What is the work done by the weighc wpl9*y twop3m*s5e*6p b 2rut of the elevator?

A.

2.75 \times 10^{5} J

B.

- 2.45 \times 10^{5} J

C.

3.00 \times 10^{4} J

D.

- 5.20 \times 10^{5} J

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a w;q*x cxt h0u5tsh8p7distance of 50.0 m. What is the net wos87cxu5p qx h0wht; *trk 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 e4bh8 9uk k.ftm up along a

37^{\circ}

inclined plane. What is the work done by the weight (gravitational force) of the box?

A.

- 11 J

B.

- 1.1 \times 10^{2} J

C.

- 1.4 \times 10^{2} J

D.

- 1.8 \times 10^{2} J

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m downlpk8 55 +x,p sifayl(t 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 suvse0l2,2jkznmo y*ym*l d,o: rface (assume no friction), with a force of 60.0os ,nd022ylkeym ozl*m*,: jv 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 72j3z b eje4luthe force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work dejze24bl7u 3 jone 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 theuhua5-tn 5+o l94re. vn2ruqp force. The graph in Fig. 6-1 shows the force versus the object's position. Find the woae 2q5uu+ ov h5.4p-tln nrur9rk 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 directionfv /sjaaesl m.vd/fk( ,-ar-l 52/ube of the force. The graph in Fig. 6-1 shows the force versus thevka2 lul fa,d(/5rv-/./sbm- jaeef s object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A.

20 J

B.

40 J

C.

60 J

D.

80 J

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Theo2nq61yisf :g graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object m6:2ny 1 siofqgoves 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 cartuc(0bkhq-eex23ol vz i k) f)d8m5dz 6 (initially at rest) across a 10 m lev(2lk e0)- )v 35q fd8dzhk meuxi6zocbel surface. What is the final kinetic energy of the cart?

A.

1.0 \times 10^{3} J

B.

2.0 \times 10^{3} J

C.

2.7 \times 10^{3} J

D.

4.0 \times 10^{3} J

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initialo g2atp6nv.d/qe:mzq;6+r ymly at rest) across a 10 m level surface. What is the final speed of the car :zq;yv6rt qepm gd6/ mna.o+2t?

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 required;0lhmk -, 3qnqv8phcj to stop the m m,qqhkph v;nl83jc- 0ass?

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 ise;4e0 sll7t sq required to stop a car moving at 50 m/s under thele7s04st;e ql 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 pr*w3k 8gmzf qh5ga(4a e9i 3lxcopels a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm.*axgg54c zi(e338 wmlkqf h9 a 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 ofsoa ;x-vi,,xu 80 N and a vertical component of 60 N. Thea-,, xusi; vox force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A.

200 J

B.

160 J

C.

120 J

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hapf u95. sr5mwg c1lb;ey, striking the hay with a velocity of 60 m/s. It penet m5sgcw1p ;r.ublf e59rates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A.

45 N

B.

90 N

C.

180 N

D.

360 N

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to a height of 1 *un(wi,l 0e3b;mwqpm3.0 m above the floor. Whwei 0l(npw;b,3 qmm u*at 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 pv+ fdbww9p2 gy cj8g9l(b kw 1o+5tj6jlane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how much wo p++gl5wk b8j (dgcoj6 tfyb2wj19 vw9rk 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 o:iy, z5lkv z;stretch 2.0 cm. What is the spring coz;koi, l:vy5znstant?

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 conbtg *x-*a4xix stant of 60 N/m. How much potential energy does it store, when**gxa- txx i4b stretched by 1.0 cm?

A.

3.0 \times 10^{- 3} J

B.

0.30 J

C.

60 J

D.

600 J

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work requiredh,n o 0cpn oi7h/;pg+v1mfr +f to compress an initially uncompressed spring with a spring constant nm+rgh ,ff+7vo;o /npc10pi hof 25 N/m by 10 cm.

A.

0.10 J

B.

0.13 J

C.

0.17 J

D.

0.25 J

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N/ e4 as/bxj6in-m from x = 0.20 m to 0.26iaben -j4/xs5 m? (Assume the unstretched position is at x = 0.)

A.

0.45 J

B.

0.80 J

C.

1.3 J

D.

0.050 J

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3.0 bpvcx qz) vm8mg 1.xt,6fv; b ,u3s*jzcm. How much work is required to compress the sb6pvz s*qx 3bjf8;.,u1c,x z mvvgmt)pring 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-m high slope. What isx em* p9 y:t9i1a7seyd the speed of the skier on reaching tiy 1xasm *9e9d :7eypthe 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 kk3e6s:hc ,ss w5ee /rng, pushes off the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast wse3n ,k:h/ e56 escrswill 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 s0 q q4qwq( mb*9fdhxp .-,wtffpeed of 9.80 m/s. What is the vertical height of the planeq4,w *w9q.dh (x0-fftpq bmfq?

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. febk.c (v.um(91a*z2tf1iw 7hccmin 70 m above the floor, its potentia 1 nm.t2aum 1zbi(7kc.fc v*w(ihef9cl energy exactly equals its kinetic energy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from ground level with a kine q) xvleq a1 qsj-av/rrwkgfi;r96:67tic envijgf6r 1kxqwe6;qaa)/s : 7-rrlv q9ergy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A.

1.0 m

B.

10 m

C.

14 m

D.

24 m

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic enet wi y hgv-y c(u2vxe1(+e7vh2rgy of 220 J. At the highest point in its trajectory, its ky7w vxe 2+-ih1( yhu(vg2 ecvtinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

A.

\frac{220}{m g} m

B.

\frac{120}{m g} m

C.

\frac{100}{m g} 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 theiw: -/vb )d2zwrmcq+k bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coastv/ qbz+imwd2 -kr) wc:er 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 maj a1l2f33s3irp s-pr 8ntm)u/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster )8 na3si3ljpust pm-a3rr21 fat 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 bfm0w8y(cbt +a47 m6wyehg.mo fv 7a7 pottom 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 . vf7+yy60pf48(gacb77mh w e mmwotatop 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 speed9i,is jieg*, u of the ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2-kg pendulum of length 50 cm is pulled 0.18 m away1mhvk/ymn+6 g from the vertical axis and released f6y1m +hmvk g/nrom rest. What will be its speed at the bottom of its swing?

A. 0.243 m/s

B. 0.649 m/s

C. 0.973 m/s

D. 0.811 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 horir99pj ymh9co25sc ;ly zontal spring with spring constant59yjp;clscyh2 9m 9 or 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 i);r,tg-oox ga red light. What work is done by the friction force agar),g;t- ooxgi inst 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 6*+oby8iif rk1)q8c -qj ibrl 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming -qrl1y)f b kr j8iicbq+6*8oito 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 kineticz5(su 1nf3ct nxu1c1c energy. The friction force on it is a constant 0.50 N. How far wil1ccu5n(13 tuns fxc 1zl 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 applietm3e r mzn1s(9d horizontally 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 r3t1se (m zm9nmoved 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 a 50-m high slope. If the work 9bn7,yl; kmj1vbsl)9us id b) done by friction b)m9sllnv9b;)uib kd1 7s y j,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. Tgnn;j+ m lomd9+/j w us6zmm8.he 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. Wha+z+m6jws do8.jnm9;/ glm umn t was the magnitude of the average friction force on the box?

A.

0 N

B. non-zero, but less than 400 N

C.

400 N

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at tgaxqg71-2: bla4o utg he top of a plane inclined at 20e above horizontal. The coefficx42 7o1ag ugb gl:a-tqient 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 fromuns(3kf ui*+ bq(bjxdsc 9 42s a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average fo ndc jxi43u b2ssu(( ks+9qfb*rce of air friction acts on it as it falls?

A.

22.5 N

B.

75.0 N

C.

225 N

D.

293 N

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a flight kb x(p mz p+q53 h)nvg6vjvl/,of stairs 10.0- vz+bl nq/5pj(vpm,6kv )xg3h m high, in
8.00 s?

A.

75.0 W

B.

735 W

C.

4.80 k W

D.

48 W

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant vp*z/nm- xen 8qy olq2*elocity of 5.0 m/s. What power must be delivex2 */qezl nmn-o y8p*qred 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 runsqzi)v0*not.0 ).dsmx x q0ql z for 1.0 hr? (1 hp = 746 W)q *sz)0x.qd x lovitq).n0m0z

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 ratqz)kf ud/x qiwei7m45r37 yt* e of 500 W while riding. How much force does her foot puy*i4trq 7 )qz xd3e5kumf/i7w sh 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 u4iup vp3nf0n8mdo4 i8(z q,xthe average power delivered by the engine? (1 uq uf p xnz4(4op0 8nid3ivm,8hp = 746 W)

A.

60 h p

B.

70 h p

C.

80 h p

D.

90 h p

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