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

1#

What is the correct unit of work edmxr6yn7i)+ehq6d4b ,c dz8 txpressed 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 no *y * po),yjofo :56wmibi;e vtmotion?

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 0i:lysplj99 q hard against a stationary brick wall, the amount of work you do9qjly i0s p9:l

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 verticalkbcno1whw843 j6w:nv2z 2nhtly and is being held there. How much work is being done in holding the box in thinw 23nw vn8k 6hhoz4bj:w1t 2cs 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 a 10-N ob g5*-fmml0 lm2d: 1toet qcxd e6mo+/xk8o.nrject, the amount of work yogrd1m ete lok:mc/8oo 2q 0*.5xm-dlmnx6+tfu do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned t mb4t-1t6iugxo its original position. If the total weight is 30 N, ht6gbi t-m41uxow 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 objectlrw9,w0 3 zucg3ixrk3 do work 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 the work done by gravdfu/;.g;vv( scwa b- nity while the ball g.wa(/d;v s;fug c vn-boes 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 Forc jp1rx5mh2a 5vg;9pi j pe4+nne versus position (F vs. x) graph, representseag x ;+n49m 5r2jipp5v1nphj

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 vhzg2ge/b /ls:ersus position (F vs. x), what represents the work done by the fl 2g/b/:zgsh eorce 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's kine3sncwt obwb f.(g0,x 6po) 54ck bc/nmtic 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 (u,tb/s wxj ;homb)6o, 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 kineti: vr2/-u aqwgfaem/z )x 7y 98o)dlojjc 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 twice the speed of the *(h 3-mi ccvavcar. Whic3 mv (-ha*ccivh 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. The arfu 7n6 m;bz;cx.m5u kinetic energy of car5czau7bm;xm f ;r u.6n 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 halkl+z a4ik;. :mzna5bv f of its original speed. What is the ratio of tzlvki :4.;bn+5aa mk zhe final 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 of 3 m/s and a pebble is movi 9uojikj +zd + 1drvt5kx(m-(bng at a speed of 5 m/s. If both objects have thi(-(z u9+xr v1mok d+jdt kbj5e same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass icw+. 3 g pfkljc+s8.bfwrsw4:s moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object+8 3lwwwc rsf:kf.4p. j+cgbs 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 skid a cerjpu1hdu (,di 7tain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditiohjp71 du,i( duns?

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 orb2t(ofx)g. xg(kk zq.hnc:ik( it. Neglecting any friction effects, what happens to the plan)k2.x. kknx:c(t ofgzhg (q(iet'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-energyw x 60)cj rdm2geo19jy principle.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

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

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

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; kx^2$ 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 energy?8y2zl9o h03anc jxw1c1aok 9k

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 objlq m0ml3,o8 xrhkgk3n f(hazo 9tm*t6 s02qx* ect with four times the mass of tq8 knsmm* 0k xlo0 *33tg2a9hq,trl(zmf6 ohx he 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 caus,94y6afdkua mes it to stretch 5.0 cm. If another 0.,adk9 myfu 4a6200-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 kr czx 91*dkz5a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its ki(qb 79hlobaqi+:a 9 yvnetic energy K, to its potential enerqy7b+bh q :9ai(vao9 lgy U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving up a hill.mk6u )+o.jd)fjq mg+y bw/jr/

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 sliding with equal speeds s 6;yead:km:o,.kdkh g)6rzl along a level frictionless surface. ,moh)k :a kz y66dgkd.e s;l:rThey both slide up the same frictionless hill. 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 olm/q.z f* bmtzr70 8.a eb-l(atf6ab$m_{1}$ 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 s b**;+rf kux*6rvlvaof conservation of mechanical energy for conservative forcesxaf6v*ubl r+*r; * vsk.

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 oyk9(z,qubm4is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the poom bk(qyz9u4 ,tential 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. Do not ignore air atc9 j7): tjdjp )uza9resistance. How much grz9tt:j9)uj)apa 7cdjavitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational z :g zr)*elu,hpotential energy. Do not ignore air resista gzu zl)h*:r,ence. How much 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 conservation of en0u:;z4fv 5 h vfhocjiji55 v(fergy.

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 iswprd tkc s*sldx5e 8311-mm1a

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 exmq8:t ( 6buqrqpressed 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, whicz4+lx1f*f eiy -r f7hgh 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 yesterdak,ldd+9+i 1qsp4 s x5dkswc ;iy, you did 3 times the work in one-third the time. To do so, your power output must have bs qsw54l+,idxip; +ck d sk1d9een

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, 9lw*t:.aqgssu k n8z+8jdv -hw o/v+c 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 auvzvpek )so2,y+5q, 2.0 m and held there. If the object weighs 90 N, how much woay+sv,e ,p2)kqz u 5vork 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 distance of 1.0 mt( a8* og)vkcorr8ae-, at a constant velocity of 0.50 m/s. What is the work done by roac*8-)k(tr e8vg oathe 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 constan3km+z1fr ajrq nha.3 .t force of 5500 N for a distance of 50.0a .h3za k+nj.r1mf 3rq 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 1- v-aj9 jv-ipri *ckcof 5500 N for a distance of -vp9r1jjiv-kci- * c a50.0 m. 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 pulledzk ,qwmd mb+1 g7;dlasg)e3w - upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the elevaqk3s),-gz ld;bwedw a7 m1 +mgtor?

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.w(bo,)nq v97s n nk.vz0 m 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.me31 5aurem-ukm. r h.0 m down a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icyevfjbl7f4 +w j *bwl:* surface (assume no friction), with a force of 60.0 N at b:f47*l bj fje+ wlvw*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 t8dt 8kyo4 3etep;uq:eaob/ / rhv2w *jhe force. The graph in Fig. 6-1 shows tho;b ey qr/ed8t/e*pvthjuak 3o4:w8 2e 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 thwd x5qu7*doq* 9mv5 gfdmx o(zfw,-m: e force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work d g9z,fwud x(-dd5qm7v x *o*qm5ow:fmone 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 force. The graph in Fig. 6-1blg/r to5/ (zfa(mu5h shows the forcmbflh aor/ uz(5t5/g(e 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)jvxe if33 mj) of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object m j3e)i3j xfmv)oves 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+,ksu8.eu1dkw8 s2 ;yw xh9/txg kcgt is applied to move a 55-kg cart (initially at rest) across a 10 m level surfk,hwwc1 us 8d2+.x t8/ yseukx;tggk9ace. 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 g j7 otbg+ckyk )2f1ob* 2(njjN is applied to move a 55-kg cart (initially at rest) across a 10 m level su f2) joj(y1+bg bnto2k*cjkg7rface. 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.blm,fh +,5 prt How much work is required to stop the masft,5+ml p rh,bs?

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 disrx 5+ fd.t0 5ck+ilw;zyee+qo tance is required to stop a car mod+5 05 w et+l.xeir;fco+qkyzving 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 7n59pb +smv )4-sp se8cngm adv3d8am force of 20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has neglig dp)7 v384g-b a8 ss9nm p+vmscn5eamdible 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 vertical compk-zpnt wt/uy)l78a h 7onent 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-t pk hy)t7azn/87 ulw m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hayarg 6ugze(-3-uc(i kr , striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stoppu3k (gegc6(a-z urir -ing force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floor to a height of n8bnmb.jnf 3l :e* px;.v9 pgh13.0 m .gxfev; p39njml8bhn.b:n *p 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 plane. The plane is 4.0 m long and ( qio:z )4egytrises 2.0 m. If the plane is frictionless,4zyi( oeg:qt) 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 to*p 1o2cq-kuwbwx-;gu3m :kb h stretch 2.0 cm. What is the sprin-u- b3 w*;qbhgwkukc :2pmo 1xg 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. H /gj:a infz0i11tk7iuow much potential energy does it store, when stretched byfi/ uiag 7tnzjk11i:0 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 a ij sz2zbx9;hft,b9p9n initially uncompressed spring with a sp2ih t9zp;b b9zjfs ,x9ring constant 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 stretch a spring of sprz/uhty 9xca,0ing constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x tzhu ,/cyx a90= 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 e 8pvxt vy;)f8of 15 N/m is initially compressed by 3.0 cm. How much work is required to v vf;x8)8eyptcompress 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. What is1p ht.ancxd2f(gr qjw.c ..,w the speed of the slier on reaching the bottom of the slope? (Nega d.h fwtwgpxc1,.qjr2 n.( c.lect 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, puuw - 4cacrf2bu*sqg. ,shes off the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after drow 2aubq.u, r4gsfc c-*pping 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 frictz k4 ,ou7pwxwdfs w.6f8xe -9:pgh/uwionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical height of tu7pu-fsh wek. dw/pxo8:xz9g,w6 4fwhe 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 abo.qxrfyqs8 6y5c:jf 8 bb4/sgove the floor, its potential energ58q .bx8r /4s6fbsgj:yf yocqy exactly equals its kinetic energy. How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blahwk,z3p .(h sqat3i+fsts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy isf+iptk h.3z w3(ha,sq 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 grz -+fjgjwr06v ound with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To rfw 6g0v-+jzj what vertical height, relative to its launch point, did it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the botu2c 0m+ s5st0jfpsgdi;)qjf5: j :ep xtom 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 above the bottom:fj;+ spjefg:t m0)qs x0pi5cuj 2ds5 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 point 45 m abv/ )val :s.ary tci: mmh3)*ecove the bottom of a dip (Seey/ai:m:c)rh lms.a e)3 cvv t* 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 above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip with a speed eisl *o0yfw94 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, whi0yl w4ioe9 sf*ch is 45 m above the bottom of the dip?

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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 th+ k8f0ngxl*rc)h g;q65rio goe 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 thes tf1pp5, 5t:yt6lj ua vertical axis and released from rest. What will be its speed at the bottom of its swingp y5t:t,6tp5ju ls1fa ?

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 uncomprmz5dgd n+)/8qoi gzr6 essed horizontal spring with spring constant of g5 dimdogzz8n/ )qr+6$2.0 \times 10^6 \; N/m$. 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 bg pp rock1+n0 h:;f5e14aeip2 dk mh0gl v+s+kg car to stop for a red light. What work is done by the friction force against the wheel;11refcgap pk ig ok2 5 0e+lsnh0vdhm:4+ +bps?

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 bex ,96z; ps1 r g8 qdbof32nigaids.3qetween 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 . 33i 2gq98r,a 6os;qspedi1 bgdnfx zto a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J o.z7j m mlg49d :ydrm;; e)v8qazblyag 2g6+fcf kinetic energy. The friction force on it is a constant 0.50dmgm zvy 97lme6c.l;qa g;2zy d)8arg: 4jbf+ N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level surfac,vjo;k4q b. en/r1 ueye. The coeffic u1.k o4b;ejn yr,qe/vient 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 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 wort)5r5c qrci-l k done by fricctl)r-r5c 5iq tion 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 ma0jfga+t mf 6 7w1u9o4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to thetg7afm+m f0j91o aw6u 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 9:uzo ans/b .j5hu1j dat the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the pland/ojnauh uz1:j.b9s5e?

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 frp1/kb*3 djg,6o v0hkr hfg .ssom a height of 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force of air fricv3f/k,g bd h.hjgo*s s01rpk6tion acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when 5zc)gx0xz. n yo c55pof(qqj, he runs up a flight of stairs 10yqnoc5z0 f (q gz ,xc5jx).5op.0-m high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity of 5tjf,1q.x ckf+t6r5zs v(o0fx .0 m/s. What pfrfks ct x16j,vf +z5(t oxq0.ower must be delivered to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs .,skxno h)- uhfor 1.0 hr? (1 hp = )ox h,-unks.h 746 W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the184ha10 2b+dhwm n1 pzn w(ahwoo0 swo rate of 500 W while riding. How much force does her foot push with when she is travelin4pz00hdm1nawo ao 8sbwh 2 1who+1n(w g 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 fromgw a hpd -wmt+v,nk3h( 76liv8 0 to 25 m/s in 7.0 s. What is the average power dei lk6h gd,aw3vp tmwh(vn8-7+livered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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