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

1#

What is the correct unit of work eyw()b o8zk mm4hsos*9)u -nnc xpressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is1 8 vu v+d ub.+*bly5xlk:eqfd 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 s39o g0ul4koe ctationary brick wall, the amount of work you d4ougc 0ke3o 9lo

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 uthr 4360 kqx0ll0grlvertically and is being held there. How much work is being donetgrq l6 u004kl0x3rhl 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 velocity carrying xmg,f* --uhlg a 10-N object, the amount of work you do i x-ggfmh-* ,uls

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 6* zolgvz1iik-),pdc y/ic1x returned to its original position. If the total weight is 30 N, how much work was done?yo* c1cipl /6 gidv-zzx i,1)k

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 th f-cfpdkm 3.xaw;*/rye 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 h1ulp;emsj35wt (7t o sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while; ul ph5j1 t(smtwoe73 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, jv*c e::yz6n p1h5cpq on a Force versus position (F vs. x) graph, represents:6vc5n*p1y p:z e cqhj

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 poszohwhw+5k jxyz74ve6/ z6 ,vnition (F vs. x), what represents the work done by the5je+wz khv h/6wn6,7xzo4vyz force F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object',rdmyfv 8f0-ds 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 negativelt:q sdulw ah*j- *4n*, 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 donei fl:h5q6k:bojq+/v b on 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 u4*sam zhl ),box-9 0atlcjc)twice the speed of the car. 4 -sl,x uc 0a )bz)9tj*hmcoalWhich 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 of car K.4 cf95 /yfl9ytsnw myl)ac c8* The kinetic energy o49 wfa) 5ccs/ly8ylmytfnc* 9f 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 wituj6).:vbp 5 bfmshs- wh half of its original speed. What is the ratio of the f .vhj)u- bpm6 5wsbf:sinal kinetic energy to the initial kinetic energy?

A. \frac{1}{2} \;

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed qm6.cz.uxq m y t27ym.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 the ratio of t z.u.m6mcxm7q q. 2yythe brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A+e a-bs4nryb; 1.0-kg mass is moving with speed 4.0 m/s. Both objects ensr4b yb-;a+ encounter the same constant braking force, and are brought 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 your car inc)h;bf3h- r s7dowe) 5wh: 9;liskhnm a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skiddkn;5));ilh73 eb sws 9hhwmrho:d fc -ed, 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 Sutieh4xp+*7l0at t 9gnn in an elliptical orbit. Neglecting any friction effects, what happens to the planet's k490a+lhn x tgip t7*teinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

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

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principle.vhi,j8+dpq ) /)ypha l

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 tzb 18v z (k-ww bdnb34p7izlk7o 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 res8nm.bo:53(kjtqv;((yu s eyjrd e2v dt a height h above the ground. A second object with four times the mass of emk :d(tunqb2 v5.j(ydroj3v8 eys; (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 sfkcma.m .3uh5t:v.j5rct 6 cry q-:dmtretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potentim.r6.c.:c q y53:av h d- rjfmmktcut5al 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 enepxr ,,6fk).ieotk b1p rgy 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.zp v, sqs0a.e dwu37ob 7)og4x Compare its kinetic energy K, to its potential energv47uqsa )z70eoowdp3,b xs.gy 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 cvg),2lx; yzkzar driving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight objectu+njn-+sy0x :je0k ne and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. jkj x:0n-+e+0nneuy s 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 4rtyee1av6 +4 bz,mvd zg-r3v$m_{1}$ 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-mt3 tnrpv3 f/ ta tg2v d0t;+n21xshd of mechanical energy for conservative forces mn t x23nshrtv;pga2-t f0d/3d+vt1t.

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 :-jh:dnkq rp jkv.9 5ofriction is present), to the ground below. How does the kinetic energy (K) just before striking :5k -rjjvdp.k: o 9nqhthe ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. zz)b3 wapz-g / Do not ignore air resistance. How much gravitational potential wa3zgbp z)-/ zenergy 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 distanceqhrmb jn4):g 6 and loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kineti6mjnh4q gb: r)c 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 of energy8 owdl1;fl5 3(gbod2laxbrl;b m( d 9g.

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+ ceb u7axquivn0i- 72

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 iyn,y , e7ol18zuok+ j 1fdh1xpn 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 notz8c .e wbibu48 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 k;x/6bk qtj i/(ea az za1+c;ework in one-third the time. To do so, your power outpu ae;jq k6bzi/cx1ae+/ ;akt(zt 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 accelx ac5mu v -dy,g1l1b32a:ya(w2x gbkc eration, 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 t s.,5ney-w7:hxz hmsjdx 3pa1here. If the object weighs 90 N, how much work was done inhhz35ny e1:.xwxm j ss-7,adp 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 physicszin 04 v+lyng2 book up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/sy 4ignzn2v+l 0. What is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a distancub 5f6wj eh5uu:l 8l0we of 50.0 m. What is the work done byj uw:bhl e65f0ul 58wu 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 upwar.wn ru8 itrm :sgrf: y ootvv3/9b3bz (.7*kdqd with a constant force of 5500 N for a distance of 50.0 m. What is the wor3sv.:ktb 7tmqbyv.9f(groin:u 38r*o r/ zw dk done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a const0uj;f l2(zxhb*(vta3 xwf 9kn ant force of 5500 N for a distanchb( k 23* f jl9xvawt(nfxz;0ue 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 up along - c +/b v0dsdd0n9tjkhzr*(uaa $37^{\circ}$ 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 ram.lm6rwt68i /pqr8l kxp, 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 surface2w d5ni ,at(vg2up 89l nnuq2t (assume no friction), with a force of 60.0 n,g5nqiu2w(t2d8 p utalv n29N 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 ga*/7 rvyu ot3ti;,wem v0w2yt raph in Fig. 6-1 shows the forcee2*ya 3wtv,i0 wr uo/7tm ;yvt versus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force.,2a28i xlqg-jfdsl bj wsr/1 1 The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 2.0 to 4 lq-a2 fjj1 s1,2bglr 8ixwsd/.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Themlv2yjan b-n:7 seo-4 graph in Fig. 6-1 shows the force versus the object's position. Find the work done when t:mj s on-ba-4y7le2n vhe 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 f y+fuhk.a *eaie11 b;norce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done wheunaa1 be*1.hyke;+ f in 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 appliewe-y ixd9l8z1d to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final kineticz-w1leiy89xd 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 ic/o6gq k5cub 3s applied to move a 55-kg cart (initially at rest) across a 10 m6ogqkc/u5c3b level surface. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.xxehtz; 13d ;h0 m/s. How much work is required to stop the mass? x;tezh dhx3;1

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 initic62w*ml ;v odw+7jnafally moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under th*jw6vfo2dn wml;7 ac+e 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 prope;6uf9-kptg-cyu rle 0ls a 10-g dart. It is cocked by exerting a force of 20- gyptk-r0l 9uuc6f;e N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horiztd hi i(.ib9+)otn* i+ns cjy/ontal component of 80 N and a vertical component of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts j y).i/i bt+ ( inso*hn+dic9tfrom 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 srpx h7woh , opp;p1.b9hot horizontally into a bale of hay, striking the hay with a velocity oxp9,pw17pop h;bhr .of 60 m/s. It penetrates 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 flooabm )u7virb8 /pu x2,mr to a height of 13.0av 8ubp)ib2r/x um 7m, m above the floor. 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 euh;ae8ilh 95s0 /iq9 ( isokrplane. The plane is 4.0 m long and rises 2.0 m. If t;ei0 8rh/q ouks9ia(e l9s5i hhe plane 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 shhn*8fgr8 +ixo3r *9l bff1uu7nmac 5pring, causes the spring to stretch 2.0 cm. What is the sprininuaru31 ho8 g9fh+rcf m7l8 5*f*x nbg constant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much sygq* nu3n-(w potential energy does it store, when stretch3qu(-y nw s*gned by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed spring with r ciqnl/;14u ma spring constant of 25 N/m by 10l;m4/qrn1 ciu 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 stevw x3w kau xci9)4j5hlw,9y7retch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstkhcx,9eww yw3x)ju45 v7 a i9lretched 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 cm. v sl*:)qwg96p6 xjp bf How much work is rep :jbv9) lpf6 s*6xgwqquired to compress 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 of a 50-m high slope. W,k4 9vhpm,.jcruefjd;5 d, z:jjmd8 what is the speed of the skier on reaching the bottom of the slope?8mhkcmj5,, :j,ep uz jdvf4r9 .dd w;j (neglect friction)

A. 22 m/s

B. 31 m/s

C. 38 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initialu q/wcs0;3pe-0q rydo speed of 4.0 m/s. Npc / us0qq-yowr3e;0d eglecting 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 inclined plane. At the botto2x,4exv r fc .1jlia:om, it has a speed of 9.80 m/s. What is the vertical height e,vi .2 jlrf:4axxo c1of 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 ther ih3c oal(;4(qm9lh r r+vlf7 floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How fast is + fao rl3(4r 9rh7llq(ivh;m cit 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, bi8 uudy:hmame 5k2sg3 / vw.9dx76jqwlasts straight up from ground level with a kinetic enei:7swg x2 vd5muem j.89 kqdwy/6u3ahrgy 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 kinetex ooufy2vem 8v-:g-0 ic energy of 220 J. At the highest point in its trajectory, it:f0uoem vyg-e2v o8x- s 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 puk+x-9q1 zhd ioint 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the rolhq-zx9+uidk 1 ler coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a pov48ow sx b)y3rint 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of thex) b4 oy8s3vrw 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 aboj65xmms.pb, 3ag vtm9ve the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above thebmp6 5.v agsj xm3t9m, bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the bd9d l738-so phdcgju ;all 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 0.24p2 h3p8 ke *u9mmun*dp m away from the vertical axis and released from rest. Wha2p 8mkenuu* dh3ppm*9t will be its speed at the bottom of its swing?

A. 0.329 m/s

B. 0.877 m/s

C. 1.316 m/s

D. 1.097 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 hitivxf*e8: 9 lwa:x)jws s an initially uncompressed horizontal spring with sprieixslj9fw* :: v aw8)xng constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 2swac1 5z+ x*/yx hw)r-t gwir;2 m/s, slows down her 2000 kg car to stop for a red light. What work is done rh) 5 czsaxy1t+-wxr* ;wwig /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 jm m77ryc7.hm a 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 to a .7 hcmmry j7m7stop?

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. d:q. sf-xn9x ay);nw a It has 24 J of kinetic energy. The friction forc;n x.qs )n 9fa-ady:wxe on it is a constant 0.50 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 mas3bc1aw pc ,3i bi7imp+s on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is movw1 7bbcmap+i, pi33 iced 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 h1 e/l,zpqdr 01sj wd0ligh slope. If the work done by fd 1ez slj0 0/qlr,1pdwriction 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. The plane is 4.0 m lm39 ymi z.p xy1,qy5ow9n bal;ong and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction o qpn5m9;3 yyl,9.iyzm x b1awforce 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 abov y +u7c+do/apxe horizontal. The coefficient of kinetic friction between the mass and the plane is x u+/oa7cpyd+ 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 froncts u-q . ex7aus)1m1m a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it as it fal a1su 7n.1utsq) ecx-mls?

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-5v,n bo4pa7 9 +m fs3lmhft-vnh0dqdn he runs up a flight of stairs 10.0-m hdno0- fm bsv57n ,f ad h4+qhtml39-pvigh, 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 a constant velocity of 5.0 m/s. Wyjp4 i-zq82mtx ts/n(qh) x( 58kznqc hat power must be delivered/(m8c5sk(qqiztz x-p 4)hx t2 y8qn jn 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 fz8:u* b0dl dlrbq fo02or 1.0 hr? (1 hp = 746r2qfb:ll 0z 8d*0u bod 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 riding3 aj iz6lw*tft-p.4s a. How much force does her foot push wswt6a. lz*3pt- f4a ijith 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 tomfui1sw* )t.n .sa fj7 25 m/s in 7.0 s. What is the average power delivered by the m .f 1.ns)isfwut *ja7engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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41	42	43	44	45	46	47	48	49	50
51	52	53	54	55	56	57	58	59	60
61	62	63	64	65	66	67	68	69	70
71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90
91	92	93	94	95