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

1#

What is the correct unit of work expressed 6 lndtm b1;rxg4,d/lj sj.hv2z1ty,i 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 is nobk+3 ymk82 zao 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 work y pwakyi8f/euc/86 r5akcai ;* oua8ic8*e6/w i a5kf;/uc yakr p 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 there. How m - l gmig2run6yu2q;,much work is being done in holding th2y lnggmm,26ir- quu;e 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 horizont9wf o dg/jwz/5peo w.)ally forward at a constant velocity carrying a 10-N object, the amount of worg o/)w5e d/.wfw9opzjk you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertij q3wxlet1f(55+. 6yqfigl+xo zox9tcally 3.0 m then returned to its original position. If the total wew.5oj 5q+lq9 ylzi(tgxe6t3of 1+x fxight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on the obx*(.3v s7ehv lolx.y gkqq:ug y-.4xg ject?

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. hqth 6)mficv 8y1fo+t oc,7z2 Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goesf,ctf+iz 6 vh) o7co28qtyhm1 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 vswcan0/ttv;3 (bv*8l;e hiaj j. x) graph, representsawh0;8 3 i(entvjl/ javct *b;

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 repqb5(u s:vq j*s)l7kkpresents the work done by the force Fqvq* 7(:k5s uk)sbplj?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object's k5czym::y jmsk j(;s2d9. j3my d,gx hlinetic 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 negative, then thehx n2 zqtkhr,*y s6 +0km-uhy8 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 kinetic ok-t fy e bz(+9b*0vrqox9f*dfax1xf- d5 i+xenergy

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 isxwm c7(;.fce c +p1awl moving at twice the speed of the cm 7( c;1cfae +cpwlw.xar. Which statement is true about the truck's kinetic energy compared to that of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of car ro .0/hu1s v/ml q.frmK. The kinetic enm/ m.1lr0ou./fv rhqsergy of 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 izjq pw4 g2pm71o97j xrts original speed. What is the ratio of the final kinetic energy to the initial kinxp2jj7 mwprq17 o4z9g etic 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 anyv le4sl)doqj ; +d2 la+em7t7d a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio os2)qd mo;7dle7l+ te4l ja v+yf the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is moving wgh k7mlz c/)nacf(pl 3k1 r5 +iorqj5by:+o.rith speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the i+:5m+h7zkqo 3pfk( )y/lo1lb5 gcran j r.cr 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 parwljq4:6sr iyn;q/1 8zc;wl )y:bie unic, and skid a certain distance on a straight, level roaziu6lrneqyb4; :1c:;rqjw /wi y)sl8d. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbitdc+d z-p-nff, s the Sun in an elliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic energy-+z- fcd ndfp,?

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 p0hjlyz (eu:9,5 xhtj59*q t8ouzqv pxrinciple.

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 86mw3 sbb l*dlo 2vbp3to 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. A second objem29go4;rcn m9*lbr zjct wijmr 2 4noc; 9mrzg9bl*th four times the mass of the first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it to stretch 5.0 cm. s i-h xv5rr p*4a 2a0:t6shsd pt+2gwtIf another 0.200-kg mass is added to thdsah ts+ 6hravs-0p ir2:tpx54wtg2* e 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 syste wp2o azpnew*)qhtug8r3wy f61 /+6akm

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 kinezv7 d8;nnpcf /tic energy K, to its potential energy d/pcz8vfn7n ;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 drivilhu8tt fnb.sn 3 : rd006qkib(ng 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 cqw;z7*4 kjs(r*nm eyb qh-7c0kvf+s heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rey 0ks7n-;cb*4 (rkjzfqw+7 vs*mhcqises 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 +4yn,r( ;sdofrgxf :q $m_{1}$ 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 consecx l: s5y-+pcfrvative forces.cpyx5f lc-+:s

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 preszlvg,jx,lz,/j0+dkp )d af7 cent), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?p,)ljvd+z,azlj kgcx 7,0f/d

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 o.v.*,i8nhg10kyc t in bxx4ls .uepx,f kinetic energy. Do not ignore air resistance. How much gravit 4. t leb8hux1n,x0 ncvp *ixk.g,is.yational 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 rrpslp k w*-1 su,nl-0i)5cmsand loses 30 J of gravitational potential energy. Do not ignore air resistance. How muchw*r5lpsp1 uc0lnsmkr ) i-s-, kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conserv7,)+98y0 tiimvtt xgsv(p oo uation 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 isqr+ops * *kzz) 2jiua5464 ldbhdpt6y

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 p h.;mr(yz 7xkpower 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, whi-z;o6 bol px5y ntkod7p92 1ejch is not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third the time. 25c gjaey; -zdTo do so, your power outpuaye; g52-dcj 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 act0kl2j0q4t5c.ceh c xceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If the object we (, z.z5tk p)yihog/je i5syk-ighs 90 N, how muc -(s,keyy5i zk/hpitzo g)j5.h work was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a dista478imvitlwlh 5-fg -5 rr.jnince of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by ill-i4r58nw jt -vrimh7 fg 5.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 f4u.o mqmefb00 xs :6jwor a distance oq06jwxs0f u.:bmm e4o f 50.0 m. What is the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a 3 nkalux*(h;a distance of 50.0 m. What is the work done by the weight of the ela3 nkx ahl(;*uevator?

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 ( o*ul+udj8n jgon51tj pzv;+pulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work dn+j 1g8pojjt5*u (lun ;vdzo+ one 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 a4iee27qg n(yx9, ey p4zfbwz5long 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 ramj4a. n hdnyc9-p, 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 surface (assum8qox 4 i:tuq,fw )j4cei;1ycy e no fri;j fw1xt:y qoy4 ue,qiic48)cction), 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 dirp:x wdou6iy 2 *pej(m-ection of the force. The graph in Fig. 6-1 shows the force versus the object'uyiw-:j de mpo6x*( p2s 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 directioya9892b n: mfbg1cinmbvp 8 6yn of the force. The graph in Fig. 6-1 shows the force versus the object's position. Fi2n8a8bmpy gf9m yv1cn: 69ibbnd the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the forcep :t( ni8k1i,: e+a0gmrsfnwg . The graph in Fig. 6-1 shows the force vers, n:0+1i a:wekfpig mgns8 r(tus 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 of the force. T1dh8e. )y nsakackc:dg/nh 76i:kdkp7-9 dzt he graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the ob:kdkc in:1a7y h7kd tdn)a 8h-6g9.cd pk se/zject 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 reston0 cy cgvw*)mj jx5nu70c/3s) across a 10 m level surface. 0jo0 y7ncvn xus*/g5ccmw)j3 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-k,m (m2jg2jgt v8hta7u g cart (initially at rest) across a 10 m level surfaceguv gm,a h27( m8jj2tt. 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 xqhskmo3r l8 bg d7i31e7 ;zj xshoc0q0 00l-nis required to st0q 0hjh8s1073bm7o0en 3qcxlsgz loxi d-rk;op 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 stopn*4m8 u 0bc b4xkmxxc/ a car initially moving at 25 m/s, what distance is required to stop a car movinnx u*84mbx4xcm kcb/ 0g 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. It is cocked by exerting a foc dhghwllga 8a)-gt (v3+4jof/ njq0, rce of 20 N over a di+vcwang l gtjgh(-/,q3)of4 a8h0j dl stance 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 horizontal component of 80 N and a veryal8p nh 6s;v.tical component of 60 N. The foy.6nv8lha p s;rce is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale oe n6cio0 dc/ :)zh5qlgf 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 force acting on the arrooile5g0z6:/hq )nccd w?

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 )nf to . zd(mme.3rqvvc1s q(5a floor to a height of 13.0 m above the floor. What is the change in gravitational potento v qmnzr.q 351vm(( ste.cdf)ial 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 4.0 mig1aqmg g5 2*m long and rises 2.0 m. If the plane is frictionles*a2igg1qg5m m s, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring poo 2b./ oyi:s s*ed5gto stretch 2.0 cm. What is the spring constantosip d5.oso2 gy/eb:*?

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 cons6ht of0*. u.spc biqp:nol *z( xnd)a0tant of 60 N/m. How much potential energy does it store, when stretched by 1b)c.6sp pfio*:ua0 xd.zl qh(0 t nn*o.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 initialla0 tbn5xe3 vj/le:mclgt0 1r)y uncompressed spring with a spring constantc arneml/00 5lgb:t )13 jevxt of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to s04+*avmv8 guf iibi2 ftretch a spring of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x = 0.fvi bfv 2*ia0u i4m+8g)

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 ini5;3a)c0v.rr)4 zbmgnk wokz ftially compressed by 3.0 cm. How.mkof wza)rb)n vcg5zr 0 4k;3 much work is required 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 fromv8 6()i vbqegj the top of a 50-m high slope. What is the speed of the slier on reaching the bottom of the slope? (Neglect frictio8bi( 6vvqej g)n.)

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, pusgtybxy+qd 1 v38ow06 .iztt 3mhes off the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m + zob3 mi dvgx6 qy8103.tttywin elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bottom, it 4)8 kzulw ;*ii ixncj+scm d06has a speed of 9.80 m/s. What is the vertical height of t4 zmcu; 0 cd)kj68wi+islnix*he 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, its potenwg (k2 3bjm s*-mvt6keoa29eatial energy exactly equals its kinetic energy. How 6mka(kmwb3e-ge22a j o*9vtsfast 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 straigg zo -*ob*uyo*ht up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it risozo *-gyou*b*e?

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 ry.lx3+s0pf-;w6 nm ojrm*cmm leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To rrjm m xsl. ym0wco3 pf+*;n-6what 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 pg8ye/bwxsf 3/ gfd-/soint 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what wiswg/e 8 /syfb xgf3-/dll 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. 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 point03*vhoa;a z (ju;app u 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 the next slope, which is 30 m ha u*3;p 0z;jpavaou (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 zo:;zf;e5 e kqthe bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the sp;q e;k foze:z5eed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottom ofm 87e/6 l(uds hpd5txi 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 vertica/bkb1 ga :gi 02zjhbv(hi4a7gl axis and released from rest. What will be its speed at the bottomgi:7 b/(v0 h z2ajgba hg1i4kb 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 hitsl:a4k ccw ;z9n an initially uncompressed horizontal spring c:;anwc k9lz4with spring 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 22 m/s, slows down her 2000 kg car to stop for a red li 3bn59sz.dwht)*uur z tu6+pcght. What work is done by the friction3rs5 .tu)wz6b9 ut hdpzc+*un 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 object and a horizontal surface isfy8w)x bb w 2nba3n9x0 50.0 N. If the initial speed of the object is 25.0 m/s, what distanc xy8fw2nnw09b3 )bxabe 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 k2q.nwt*st 6.pa(zt t 24 J of kinetic energy. The friction force on it is a constant 0.50 N.t*ktn 2 pws(t aztq6.. 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-k5 ik;t n)pvpr8(+vrzdg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kii8ndvpt r+p)k(z 5vr ;netic 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 slog/:6g -;9zs 0qpl0t tc;k,y uvplcdtxpe. If the work done by ,cv lgkg / 60u tx:;pt0d9s-ctzpyl;qfriction 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 and;g,k myz )qs6f rises 2.0 m. It requires 3200 J of work to get the box to t)skfmy,6; g zqhe top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top30bn4 bc*gq,cdl c;k( qheaj:mft3+n of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass aa+h 3ln;:jdtcbnk( qg c 43,bfq *0cemnd the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a heightk;0; dx+0yc5y r tcmjk 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 fallscc0 ky5yr;0+ mdkx;jt?

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 uspe+.: ,phc0jglb 483wwj;r ha bgr cm0w:u)iming energy when he runs up a flight of stairs 10.0-m hig 8rjm 0+ p: ui:me) ga,lwr0.cgchhw3j;bwpb4 h, 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 wijbat8ie omq h7;2 o+k3th a constant velocity of 5.0 m/s. What power mui;m8qak+7 h to2b 3joest 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 that runs for 1.0 hr? (1 v n3l,pyb802s.ak .sie7m f (vy 3chmghp = 737,enfk y3(8c.i.smbg0 y vsa2hvmpl46 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 riding. How much force doy(jr0vdxkm lw7mx.r)yh 4 a,,es her foot push with when she is traveling(wm .4,xjy7d r,xarmlyvk h)0 at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. W2/nh om; wu.ljz5:kte hat is the average power delivered by t:5uwm ;knjh .ol2/ ezthe engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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