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

1#

What is the correct unit of w. bjv el2,e-fuq1fnjih :m, +cork expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a e* xngx9+pmmzeb ;zr2;g s65y 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 against a stationary brick wall, the amount of wor7ovk/wpf3ey-d ,batxl:i ix/i: s+ y2k yo vdobt/se w+x: /3ykai27iy -:xl,ipfu 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 liftl 2 76lnlacqmh 0.zxgo;l0 2dbed 2.0 m vertically and is being held there. How much work is being done in holding the box in this . xb0anq ll lhgc27o0d26l ;mzposition?

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 carr8 7ghfmgsji(,;goby- ying a 10-N object, the amount of work you do isi 87go(ysgfj;,-b gmh

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 verticall cce69ae up)w66gl ,cey 3.0 m then returned to its original position. If the total weight is 30 N,)g96 p6eewc 6ela ,cuc 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 wor,d rb zc/0:stlk on the object?

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

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

C. No, because the object has constant speed.

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

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign of (e .6su3nuz0ygkqh t5the work done by gravity while the ball goekn5g0zsuy6qe (h.u t3s up with the sign of the work done by gravity while it goes down.

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

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

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

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

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) v8d87imq (de feis4h4 graph, representss7 dq h8i44eidm( fv8e

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the work donv -e5 eyu/w0n; q/wtree by the force / we-;ty0vrwq/e5eu n 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 posi+)z 8/u*n04pmzbro8 ei gabtptive, 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 negatn-3j92tw v(h,hf mrt aive, 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 object's kin4xjv04j.xvnv(d h 4mp i9)jubetic 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 mucht si5:n atwwoh+l9+f - as a car, and is moving at twice the speed of the car. Which statement is true about the trucka n9hl +t5s -wfot:+wi'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. sv bqs)2a;u8c The kinetic energy of car J, cq8bus)av;s 2 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.0j fd16gi lkov-yh(n+ What is the ratio of the final kinetic energy to the initial kgho vf0j(-yi +n16kldinetic 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 movl:k9 ah btc8 c,xij4 a 1f;4e-hjve2yying at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass 1v4y hxe4 ;-ic 2tybfa lacje9:8h,kj?

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 movingdh0wv9n4j g )e with speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braki04ndj 9g )ehvwng 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 in a panic, and s)5v t :7.ve elajbm)tdkid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have sl )mv)5:ted7vj b.ae tkidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elliptical orbit. Ne;i pb p ukc6uam+r)kmr +2(qdu7cp /b:,nar2 pglecting any friction effects, what happens to the plane:m2n2,p bkb + /pdp( 7ur) ccqkaura;iur m6+pt'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 p6)w2bkb w.ggnrinciple.

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 to have negative potential energ/ e 3 6n:)u+cwbomwfajog,d g/y?

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 hmjg-1 wx ;l r09d2jvmh above the ground. A second object with four times the mass of the first if released fromm9v1gdhx ;j0j wrlm2 - 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 caf mz5)+if9pztn/x1m nw;wfo 61t9r bjuses it to stretch 5.0 cm. If another 0tm1 n96f wf 9xp/wi+n51)fzzrtjb; mo.200-kg mass is added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a +8wh;f9p fwagsystem

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 tre inyxdwlzx :y u14+70ffw/e-y e. Compare its kinetic energy K, to its potential energy U.-4u/y+x 07i wd:xy1enwzflf y

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 wjxfzr+0 7-n)i6isenmn a *:y a car driving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are slidml qoepxu-x0p -;gisn 2 ggn/o000jm :ing with equal speeds along a level frictionless surface. They both slide up the same frictionless hill0-0 e/-m o0n gjo02gpu n:s p;qimgxxl. 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 4.g/e5xpg hyq-9rru 6 )lw dlxuch:,g$m_{1}$ 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 ktdvuttl. f qjna97 0046pof mechanical energy for conservative forcesp +dnok6090f. lv4 ajt7ttqu f.

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 th3b//2oljv5.okexb) 3 injdx ke air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare t5jbo kb.oj/ vx32x3ln d)kie/ o 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 anda,-ji6. cu ,icx9qq r+x7gifx gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitatiocqx ,x ax 7jq9,fir-cug. ii+6nal 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 andb2g5qukg c:e4 jhcj 0) loses 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy diq4j2gbh 05:k jg) ceucd 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 conservatil g.q dc, 9*fzjvo90oton 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 is daq9*ceb;05+uol. c -ibxijd

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power expressed in ol 4 gu.fb0f 7yd*z(fySI 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, whi yodc,. b6tx9hch 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 one8ma,l 5 dekh26tg ;sbl-third the time. To do so, your power output must have beheld,tbl6 ka g5ms8 2;en

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant acceleration, the car's engine mus n/dto rv xy.zzw7.r92t

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 2.0t7h ne+q-bg1ia3ej6 )kt or q7 m and held there. If the object weighs 90 N, how much work was don j+7qi hg76t3r tb1e- )oakenqe 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 a distance of swvgu3q(3 ,dk 1.0 m, at a constant velocity of 0.50 m/s. What is the work done b(sgu3v ,q3 dwky 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 constan acw)xgh 5nm73)ud1b0rkiw7nt force of 5500 N for a distance of 50.0 m. What is the ww n07c)db)a i13gwr5nm7 huxkork 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 dfw*g;b-4ss : zcsqd)gistance of 50.0 fgd* zwss;q) -bgs 4:cm. What is the work 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 constant force of 59en,l/l z vpn+ evj,0a500 N for a distance of 50.0 m. What is the net work done oe nz+pvnl9l,a e0,j/ vn 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 mqp c pxow/8e yqpn+pj.;/ex 5245dvwu 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 down a ramp,m tyi6i).cf gl6p2u *x 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 sle:g*uq.0mukxh d on an icy surface (assume no friction), with a force of 60.hqu*g0x u m:k.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 fle,4+u s9 m:t hw xlmr7vzld.(orce. The graph in Fig. 6-1 shows thee(7 l4lhu xmr:t.wvd+9, zlm s force 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. The graph in Fig. 6-1 shav(v5r 8znb3o ku7f(pows the force versus the object's position. Find the work done when the object mvf 5p7o8bv3 r (uzn(akoves 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 dirh efys(:; ti/..ux pfhection of the force. The graph in Fig. 6-1 shoht:.i/ uy;hxp s.fef(ws the force versus the 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 rhl-xg4 s*lprux d 4;/ ,z+itlof the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object mov;rltu4z*xli h-xsgpd + l4r,/es 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 av 3)dq,hkojl8u5w 1e89 lq9 ykbv6d wi 55-kg cart (initially at rest) across a 10 m level surfacd w 9ljh yvu o)bdi6kk8qw5qe3vl 981,e. 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 (initially at rest+ lcr9:.lxukr) across a 10 m level surface.lr:.lr+c ku 9x 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 5.0 m/s. How much work is requiregad ln50flqr9e v8xb2d60*qv d to stop the mlg dqa 5x6be2l0fn* 8qd0v9vrass?

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 is requ uo56dyx8lhi3ired to stop a 3udxh6oil y85 car moving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10-g dart.fk+0nv;ea d b+ It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible maefadb 0v+kn+;ss?

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 7 jt *qcpre/r9.,x)9 pvxzaei6 :gflfcomponent 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 from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinet* v.zprpfe ,t rf 7jqixlc9g:ex6/) a9ic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, striking the hay 9d8gjg2gpkk 0j3zxl: with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping zl jxggk3k9jdg8p: 02force 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 bck8glrc a1q/)l.4re+ p;s5 akv,g z xfloor to a height of 13.0 m above the floor. What /la rxcrvgk 4g .es)lk5b ,;+ zq81pacis 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 inclx(82to2 ttgi mr2q. soined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how mucm22or o8xs itgq2 tt.(h 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 ontx*up)md3 4a dko a spring, causes the spring to stretch 2.0 cm. What is the spring cud *3x)p dma4konstant?

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 cons. ;nnpvwe, 5hjv:frj6 if7q4jtant of 60 N/m. How much potential energy doeh4re; fp jjw6v,ni.q: v57 fjns it store, when 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 required to compress an init lqa 83jt2mq; :9ewghrially uncompressed spring with a spring constant of 25 N/m beq :j a2w8hgmq3 9trl;y 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 constantn ab/ihqc,l/g1nw07 uc6 l.u f 40 N/m from x = 0.20 m to 0.25 m? (Assume the unsnnl 70au.//, 6buc1wci gq flhtretched 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 3.0k)m-gmy; hdlclm)+/qw v4k;z cm. How much work is required to compress the spring an addi4 h/+;cw ml qd) ylv;mkzg-)kmtional 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. Whatd sheqb9qxf y,)*-b a6 is the speed of the slier ohqb sbxaqe*6-f 9d,)y n 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 avc+ns u4 8rj8ln initial speed of 4.0 m/s. Neglecting friction, how fast will she 84 jv8scrn u+lbe 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 planew*fal kd 7+;kt. At the bottom, it has a speed ;ldt kfw *ka7+of 9.80 m/s. What is the vertical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m above the floor,8z sn6fbwyo,a cxw;s:7rzhx-4 gr)x : its potential energy exactly equals its kinetic energy. Howx-7a ys ,cwb: wrh;f)nszz4xxg6: r 8o 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 zl(ey c/51m+ w:lxsuistraight up from ground level with a kinetic energy of 40 +elwlium:/1z( cxs 5y 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 grounduoaw :g-f*yovv+zp cu0z-1w:)5q so u with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic)c-u oz:vq 1w+ o0aufu o-w 5gvpyz*:s 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 abxnd:g5ibt du( jzu c9 l8i(*/zove the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which (buzt9 cni8*zudjdl gx5i: / (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 (y h2t5rzd8yj;idhdb 6k6w a8at a point 45 m above the bottom of a dip (See Fig. 6-2). Ndb(i8y;52hd aj y6d86 rkzwt heglect 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 thp() r0kn/otyi5wlw) wiz3i 7f e 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 the3pi50 i(rt )f7)oyl z iwwwn/k 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 spen yr(t1+alz6b0 qjpv*q,e8uved 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 pendulum of length 50 cm is pulled 30 cm away from the vertical axis and r3wz4 krm7,japeleased from rest. What will be its speed at the bkm3rpa,4 jzw 7ottom 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 uncompressed hormsu aen ( lwy)3/29ev.yy c-svizontal spring with spring constant v l3 2 y9nvec-y)/a(us. meswyof $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to stop for a red,ri8+2ei *okwxe k:ng light. What work is done by the friction f r 8e,e+no2:gk kiw*ixorce 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 object and a horizontal surfmj 8uzmxio 9v8h0q/0aace is 50.o mm00/ux v88jiq9 zah0 N. If the initial speed 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, level surface. It has hpaz:yiqo yb6z80l mk ,;b+xh4;b 9hh24 J of kinetic energy. Thex,hzh bam 094; 6 l+qbh8yy ;kobhpi:z friction force 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 horizontall452lh f dlk+rl2 j*rpry 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 masf52p jrlkd hl r*2lr+4s is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. If the wo1inwmd56) jcd4 jnk)hrk done by friction is4dicd 6mn n5 )1jkhwj) $-6.0 \times 10^{3} \; J$, 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 an9fz/lv :im-yp inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average fry/m 9vlz:p- ifiction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a plane inclined atjt3m l4z-ud;c h oxan.c3:7 eion2 /,1h luyqj 20e above horizontal. The coefficient of kinetic friction between the mass and the 1tjc .ou: qm4 ln37nc2/3djl ;zih-u yoh,ex aplane 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 froev4v p)aeys)6 m a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What averagaye64p e ))vsve force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using ene,es io0 du:/82jl uvxirgy when he runs up a flight of stairs 10.0-m vd 8l2s ,0u/o:e ujixihigh, 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 w2qg fd 9ap50inith a constant velocity of 5.0 m/s. Wg5 q9f2pai0dn hat power 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 my uh 1a7t+1gd3p.k y b4 s ;f9y0/;rfhxrholsare used by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 74u0b.df f1 yhkg at9hoph4y +s/yl; r1r3m7x;s6 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 5ze zub*a c,t(t ex v98,ug:w-a3t ouewhile riding. How much force does her foot push with when she is traveling at ,t 9u:x ct baz,eve-toa (5w3e8gzuu*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 4knttljz9w4 + 25 m/s in 7.0 s. What is the average power delivered by the engine4t kt4j+9wlnz? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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