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

1#

What is the correct unit of work expresvh1vjq5n+,b ig;d zu7 sed 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 at64 n. j(qsjcf system 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 agai4qfukbw 2j, v-o(ot9inst a stationary brick wall, the amount of work yo bqt4i-o j92 u(vfw,kou do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held th ;rh/hm.rae6r ere. How much work is being done in holding the box rm/6.hha;rr e 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 horizoq3smp)wrl+ + occnpwv1 rn888 ntally forward at a constant velocity carrying a 10-N object, the amount of work y8pw wn1 lsc)pcnqm8 v +orr3+8ou 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 retur;n:r:wwu9m6 t zft+nrned to its original position. If the total weight is 30 N, how muc+ 9r6rmttfnw:;nu z w:h 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 8 vk57cg ohxnj-uu4.jthe 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 straig4b+7u zjntxh;.vi q4rht up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by t+hnzqr7jub 4x. 4i v;gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) graph, represedy;.(2dt nrf cnts n(tcy2;dr f.d

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 pos( stp7ye v8p4zition (F vs. x), what represents the work done by the (pzsv87p4 tyeforce 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 positiwqyys8y0ob pm 9sa+v(/ zh vj* m4*a3tve, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is negaom7bkv/(ep +7mgt jgan 0a6 +ptive, 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 s8o9 0uqmudw8 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, uo0)s t cv gk9keyfq -8co96i;)owk;land is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that ookk8 w k;f9u lv-6 ycego90))ciso; tqf 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, o0l5qh-bif 1r+ic vo796zbhg 1kv qf5 and car J has half the mass of car K. The kinetic energy of rc5h7f+zl ihv6o ik 1bov- 5qfg901bq car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speed. Whtn 8qkt xw+6mywm9m45at is the ratio of the final kinetic energy to the initmtw n4mqm 68k+5yt 9xwial 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 atdl7 fkhf 846vak)k2nr a speed of 5 m/s. If both objects have the same kinetic energy, what isk26f 487a rhkkl fnd)v 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 gmhh; e plabs(1a(:0b2.0 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 travels the greater disteal a bh1s((:m 0hbpg;ance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and s f.+loq1 seigjd37h f1kid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under 1ffjlgdo3e. 7 i+qs1 hthe 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 elliptic pdy6*tdoux -;fdat*lv/h( 6e8fefk vry-r-6 al orbit. Neglecting any friction effects, what happens to the planet's k*rdep* hfyddtv6 fe ;-l6kyf8u t -xao-v/(6rinetic 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 princy0 uqaqd6 * r5h/9s++rx yghnwiple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

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

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

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system j-0.7plo dnb xto 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. 9 c nqh625exriy r-el8-9tgby j- d1sa A second object with four times the mass of the first if released from the same height. The potential energy of the second object compa2 r8 qy9dixjg 9l -rsca-nt615hbyee-red 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 stretch 5.0 cs6a, wattp,g l jm758cm. If another 0.200-kg mass is added to the spring, the pot,a7s65twc l jtm gp8a,ential 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 e e*a+- 0xa y+wi/wircynergy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to its potentwz*+lj1 -ixp v(nzn: zial energ( izlvz * :-1xwj+zpnny 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 kt ; yhub+7n73*qjl z uldtf46a 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 he5ekl+ g, 4-tnhd o(jyvavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. W ,-nk v(tjylgo 4e+5hdhich 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 qg2w * ji age3m3b*s-t$m_{1}$ 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 conservative forzk c)oa+ uo.j3e:as3;um q/nfces+muca e 3ns:qok/.3o;)zaujf.

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, through the air (air friction is pe,hnvv:1 ;ce8*hor87d v px wcresent), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the p: vxo;1e,* w8hnr pvc7c8h vdeotential 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 anu 1 gt1:mjou(id gains 30 J of kinetic energy. Do not ignore air resistanc:uumgti o1(1je. 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 los;c.k ryp) up(89ke kfbes 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gabpeu rf.p9y( k)c;k8kin?

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 conservu*uyh5tc4,h e ation 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 isfj ;gvywr 3+ rz-p8e3g

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,b)p;;th 4sq*s-5s aax i bf: jaxw7ix of power expressed in SI units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit a6wxhii7 *veqt6 ukm55k ( l+kof 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:kgq.a3mwk, ujqs4rv:f 6t 4m, you did 3 times the work in one-third the time. To do so, youkj f4s3vuq 6qawt4m m,kr: .g:r 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 con09mfjq/fn-;beedm;- jq4 tuz stant 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 theyj 6h ).xsfaew7eb hpg-8. 5qnre. If the object weighs 90 N, x6wh5bjsg7p.8q f )en. - aehyhow much 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 b9 ia)ijtv-6lup in the air a distance of 1.0 m, at a constant velocity o ivti-j9l6 ba)f 0.50 m/s. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upjy/xm0+(he b6e gi*qpward with a constant force of 5500 N for a distance of 50.0 m. What is the worke( eb*/pi x+ 06mgyjqh 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 lb kswp 0cj4h80 i.oak/u- ob2a constant force of 5500 N for a distance of 50.0 m. What is the work don2kb 8ow/ip.s uoc b a400-lhjke by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 55-qtn(8tt n+wb*t c:b br9 :wkq00 N for a distance qbwb* tt(ctnn:wrb9k qt: +8-of 50.0 m. What is the net 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 u9 x cwpd u8o)ey 6+edfzb3 9ie7e)6/ibwof6 lsp along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp, inclinedkovzn.l 8te;f:i::x) jzzmwp 6r9wh7 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 ) vrvtq)/fj(ub6xl4 o ;0mqkia sled on an icy surface (assume no fri4q) ;0vfbquk)mjvrtl 6 ix(o/ction), 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. oif -m /q9fy 0u1kubc4 The graph in Fig. 6-1 shows the force versus the object's position.kfquyfu19cio0/ bm4 - 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 direction of the force. The graph in Fig-nz25. x xgrbh. 6-1 shows the force versus the object's position. Find the work donegr xn-x2.bh5z when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of a-t b+7bzfb9kthe force. The graph in Fig. 6-1 shows the force versus the object's position. Fb+ t za-b9k7fbind 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 directionwn(kx64n3 x+l e)ksy k9ivab( of the force. The graph in Fig. 6-1 shows the force versus the object's position. Fi3 4( x(abw kx9ise6)vkn ny+klnd 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 res. sj gp-j 6*q;:jpbczjt) across a 10 m level surface. What is the final kinetic energzjb;6sj. qj:pgc*p -jy 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 (initially at red1kj6x bk 9pk+5jt,fz st) across a 10 m level surface. What is the finaljxk pjk k5b19f+z t,6d 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 worxdf4.pn9u )ormfw.n e/wl-t 6a x 2iv/k is required to sta.-lidpxf.mtw/ n4 w o/6vu2n)9 rxefop the 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 moving at 25 m/s rv2rilpv-) b(*7ka8hz)hnku, what distance is required to stop a car moving at 50 mbu i87hzpvl(n k -v*rark2) )h/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 guy,j*gf ed hgfu zcje*p6i(e 6,(a1t4z n propels a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will thegdugz *t1* h6jeiff, 6z(cy4ja(,epe 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 hwmx7kz4j .(;pnup: ya ua8 p:p0s4x fvertical component 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 horihxwx;u(n azsya4. j: p0pupk784: fpmzontally 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 balev vjs1 ae+) l.q:db ey16pav)q of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping fospal v6v dvq)+b1 1.)e:jey qarce 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 h4;4bjj rm+w z 4zuxiq6eight of 7.00 m above a floor to a height of 13.0 m above the floom44;j +b4quixj rwzz 6r. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is. xk/nqh x/k)x0 hd2kr 4.0 m long and rises 2.0 m. If the pl )/rq2 .kkh/0 dxxhxnkane is frictionless, 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 spri6x 7 , nqt u6f,fjtfp98rybu (+zhgx(lng, causes the spring to stretch 2.0 cm. What is tht( lrxx6+tfz ,bjp6fh9uuy (7n8 f q,ge 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 characterized5rsvnr 2)zh g: by a spring constant of 60 N/m. How much potential energy does it store, when stretched brz h)r:52nsv gy 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 uncompres 0k3da vy+wiz;sed spring with a spring constant of 25 N/m by 10 c +izdwvy;a 03km.

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+51j:yd8j mz42(etnjgslbxdp9p 3 xe spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the2 b:p8s5 jd1njpe3+d(g4t xy x m9jzel 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 1mv(,2wemn otd v16/xx 5 N/m is initially compressed by 3.0 cm. How much work is required to cnxt /vm2,wovx1(e d 6mompress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top s r/0xp4aid: +u,v2;jv icgmdfdi -/lof a 50-m high slope. What is the sped : f-xl0/ ;uig,v+r siam/jvd2 4dciped of the slier on reaching the bottom of the slope? (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, pushes off the top of a hill with+ ,qx ;f.mqn)l(ceq jf an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m in elevatj(+ fnfqx, l)mq; eq.cion?

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 sd(wp .y 3jw-zhg7g;ap zl v;,gpeed of 9.80 m/s. Wwzl(,dg ;py -hapz .wg3gv7; jhat 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 flooohw*)fd/91x e xlcvv-r. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it movingdo xv/9 -xew*l1)chvf ?

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 straight52rktr6 z/eidwh1a ig :1 nre; up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, itsr/in1;5: gt6rr id 1weakhe 2z total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energy acjpq*pz:p +0d64j 0onfzif 3 of 220 J. At the highest point in its trajectzf+* fpj ioqj6d:3 np0 ac04zpory, 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 point 45 m above the bottom of a dav4 v-0ojk2dmip (See Fig. 6-2). Neglect friction, what will be the speed of th20v4mvod -kja e 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 startpx;z+ /+ud(e7a3ox pk tsdmysa9))uts with a speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Negle+s3pk(x au ty7 p9e+td;zo))du /s axmct 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 botto)r6dt aa+9v bom 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 above the bottom of the)6 b+dra9avot 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 i/,3,j zxdlrdsa4;5p l m2ntld ts 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 lueyj ojnp/6 l :8n9zpcdbi;y8x*s)/h ,b x /nvertical axis and released from rest. What will be its speed 6ue;n,j *npl/9j8 s)nd:hb8 ypzboixx/c /ylat the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompreseiopl4skazqi bs2-/ 7)fj5q6q/4h ddsed horizontal spring with spring con2is4j-6p q)e ikz4 ddqfls75qo h/ ab/stant 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, / vfshq3scas.v)d y4.slows down her 2000 kg car to stop for a red light. What whdc / fssyv).a34s.qv ork is done by the friction force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg ocmj 8x be;/sylo7t( 4ybject and a horizontal surface is 50.0 N. If the initial sye( m cy /xjt;8bos7l4peed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, lg ixb2-xi/x m5evel surface. It has 24 J of kinetic energy. The friction force on it is a constant 0 xm2iib5- xgx/.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level s)6 wgi0spgpcjdzk ir61j/i1o6vd.a 7 urface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distancev1r6gco7z) ii jpisj16 gadp.6wd/k 0 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. Ifnfeou i;1nbc4t b f 2uw7*(cy5 the work done 2wt14 cynbbu(f57 ;o* ifnuceby friction 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 4.0 m long andh0 ius .b xp-uz:qb8-qfwq5czvq0,3 l 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 0bq,qqp:vc8w- szifuu5 q. xh30b- zl 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 the top of a plane inclin6 ;howwy7m h)ued at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. w;mw yh oh6u7) 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 the ground wit2sh*hq r./bnah a velocity of 7.00 m/s. What average fob ha2rh.s*n/qrce 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 whe(w:jx i w* kix* ouk;7j5dqot-n he runs up a flight of stairs 10.0i* (t;kj57oi:o-u qxxwdj k*w -m high, 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 object with okimy(wkv06 5 a constant velocity of 5.0 m/s. What powe yi65 m0(wkvkor must be delivered 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 tha4 xoz4u1 4n8 ;jxprrhors/x2w t runs for 1.0 hr? (1 hpupj8/ 4rno 4wx rx; h2r4xszo1 = 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 odtj9mrkps+q * 65s:-f x* *klyt/trnkf 500 W while riding. How much force does her foot push with when she is traveling at 8.0 m/r+pynkf9- m *qrltssj: * xtkd/*kt56s?

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 3- slxz4fk3osdom9 p:in 7.0 s. What is the average power delivere4sm:dp39os -xfl zok3d by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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