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

1#

What is the correct unit of work ltjmd,+ops +7expressed 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 there0e8mmaa;g;jv3i )ka i 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 workg3j0p-s em5dy+k dk y );5lxck you5kky5xk+3spe d)c;l-yjg0 dm 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 25e u;wg7pgu2z5ib ;kehrqv 8there. How much work is being done in holding the box in this;z uu2e5k;p 2vhb58g erq7 giw 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 1068 gbsqwy j39l-N object, the amo js8 gy69wqlb3unt of work 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 vertically 3.0 m then returned to its ori 9ixn3b fe6wk(ginal position. If thf9k6w(ei3 n bxe total weight 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 acti,/*yr v 7si(yjgz*bp6cb-cos0 gtb1gng on an object 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 thr+aalhftl x+dn. (,z mn u6g-(e sign of the work done by gravity whilem (ht agxd 6fa +ln+z(.,r-lnu the ball goes 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) graph, represet vhpb)b2q b-*dq3g2-lc av 2unts*)d qlb23b2gauvq pvtc--h2 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), whh cv.sfjas /q n/m4yg 0/wyvzx +r7)i8at represents the work done by thms w na yrsz/cj/hvq74 v8).gfx+/i0ye force F?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

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

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

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

A. the kinetic energy of the object.

B. the potential energy of the object.

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

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

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on (/g4y0gd wweian object is positive, 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 n3cnx5ba3*d :o+9fw;c pt(v vd( alba jegative, 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 yvx 9 17rq3icqis zero, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving36ez .po2q*fs fnz qg3 at twice the speed of the car. Whiczgsfqpzn3 .oe 3*2fq6h 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 gq:f 3*rg4b(it *hoqacar K. The kinetic energy of car J, compared to car *gq f: h(bt3ia 4q*orgK 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 witiuob,h w ) 8pkeyifq51.:/rjah half of its original speed. What is the ratio of the final kinetic energy to the initi5frp hei:i/jyqa) wb .,8o1kual kinetic energy?

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

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at swq akeu23 pz;9s y u;nlh3/s)*stlg4r lm44 na speed of 5 m/s. If both objects have the 4s*n44 t;sr 9kawe l l) qlu sh;3nyz/gu2ms3psame 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 dq3ul: d0d*k:isu7n n1.0-kg mass is moving with speed 4.0 m/s. Bot dud:sl inqd30 :7*uknh objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of youla esxs/t-,p0b*+ j kkr car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as jbe x/ sl*,s+apkk-t0fast, 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 orbits the Sun fvjnkkb l cq 93,f,e4;in an elliptical orbit. Neglecting any fric, vlqknkj,eb c;f9f34tion effects, what happens to the planet'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 princ rdcxampe++ m 2,.7bvoiple.

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 ha:g:7yw4 e6pkzz( lq eove 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 releasedbw)hkwh fih453,jf2q8)fwl w -d m hj5 from rest a height h above the ground. A second object with four times the mass ok)ffhw 5,jhwf)qi hj5dhl m3-b2w4w8f 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 stretijtn62v- b swu:yn)k ,ch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy o,2ykj 6tbvu snw: i)-nf 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 ene.f4uw ittr j+a8kc y76rgy of a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tq3j i nd3o*r8cree. Compare its kinetic energy K, to its potential energnq r* 8icojd33y 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 driving0 kq;pgbd1fw: 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 sl)lvqfnn8 y.n5iding with equal speeds along a level frictionless surface. They both slide up thevy5n8 f.)ln qn 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 m4-xxh6 ig:ch0 balh0$m_{1}$ 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 conservatib0; r :yecppohc1e/1cm al( 4won of mechanical energy for conservative forces.cpcrmcwhe0(; bpo1le :/a y41

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 fricys wfa ,9mv33e)tpkm8tion is present), tome3 st av9 fy8),pm3kw 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?

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 enerml; g xk d)lobpfh83:(gy. Do not ignore air resistance:ld;okx8ghf3mp() lb . How much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitational potential energy. Do db 7l m7gf0 y5ycbby-yy;le;1 not ignore air resi5yyc;f 1begy 7m7;ylyd lbb-0stance. 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 conservatilcsl4425vrv5wf6d yion 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 is3d7m-dw 73 g:orjan/v7fq zg u

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 rkghmh jjr2,;h0:6i srmtj smo18; 9n of power expressed in SI units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit of powe8xaqhab -8 j u) fm-xnbk2tuw2;e*2unr?

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 thy;i c(ov6(f o d 6rp.7qxqpvo+e work in one-third the time. To do so, your powerio6p q7pcx .qvr dvoy; +6(f(o output must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a constant accy8 2ywxzyj;:xbv v+evj;9bv5eleration, 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 obj)xn h0- gn go 9j7sj07y:enodgect weighs 90 N, how mucx n70s0 je oj-g:oyhg) dn79gnh 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 distance of 1.0 m, at zi r14az/4, xew 7zl u-cmt.wua constant velocity of 0.50 m/s. What is the work done by the weight o4zwcmx/ li1-zaztr.,uu 7e 4wf the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a di5e 1nymdtc bc on5q/h6r3/n /: zps6histance of 50.0 m. Whit536on:yd/ rncm n5 /hze hc6b1sqp/at 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 is9sb30b z7 uoasxj9c f: pulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weigh39 f7o zuj0s:sb9 bcxat 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 pul7 hrcgfkoq;,. led upward with a constant force of 5500 N for a distance of 50.0 m. What is the ng;.hr 7qkcf ,oet work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled v+j+ 8 rdd ctkvm-iee4j192td 6.0 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 8.0 m doquby/n 0/5aps wn 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 Sarahkoe.7 f2f0p oa in a sled on an icy surface (assume no friction), wi 0oe7 o.kfpaf2th 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 lu,v otrzoe::e:w28wdirection of the force. The graph in Fig. 6-1 shows the force versu,olw ee8wtzr:u o ::v2s 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 objsg4ho- x;i/dhb ,,ayqn 1j)zy ect in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done whenhb 4qzi/s-no ,g )1ha;xydy,j 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. j4ze*5g zl ffe-yjh)+g 3ctp -6-1 shows the force versus the object's po jpjf z- *gfl +z3c4)5-geehytsition. 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 obj6 xmhb4td mjq w0g4*fdpf.83vect in the direction of the force. The graph in Fig. 6-1 shows the force versus the objmfj8x3w0q.bmvf* d ghp4 d6 t4ect's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg ed1oen8b6a:a gi u0z2cart (initially at rest) across a 10 m level surface. What is the final kinetic enea6nzd02u 1e ig8e:obargy 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 (ini ij677 wis3idztially at rest) across a 10 m level surface. What is the f6i 3di7zsw7ij inal 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 required tn.hp 5rzbn*6jd; lu4jk dz r6w ;.nm0mo stop .;zb6ujn*lj6phn 4rrm wd5 0nd z .;kmthe mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what hk+ 5jpgvgya:p(ki 6eh/ app - *ms2w(distance is required to stop a car movinv6y p(apk pg+2w s*gpeh5(i/- ham:jkg 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 p:48t 4 dm lpwz8hvred6ropels a 10-g dart. It is cocked by exerting a force of 4 rwt 8dl: 6hpm4ez8vd20 N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a hzus+r (iu - nay8;:nwcorizontal component of 80 N and a vertical component of 60 N. The force ynszia:wnr+;8(- uuc 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 i/nt ea4ixr( ku10qvji8 dvq54 s shot horizontally into a bale of hay, striking the hay witheqq1 04i4tuni5v xkv/ a8(rdj a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m abo u(xckq1( q2mrve a floor to a height of 13.0 m above the floor xruqkmqc 2((1. 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 pushei))r aqs7ph* r9ubfe1d up an inclined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, how mus91aqrre7h* i )u)bfpch 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, caujdvw: ,8kj n6gses the spring to stretch 2.0 cm. What is the spring cjg:nv8,6 wjd konstant?

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 6w6)h vn luf :.5n,cgpzitb ;7m0 N/m. How much potential energy 7zcwlv6thn:;b.ug5pfmn , ) idoes 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 initially uncompressa /x 2 l;z,g0,vkwoy/ gy*gdsyed spring with a spring constavg ylo0yg*/dkw,; xs,/zya g2nt 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 xni/bus0wm( l- /oo 0pspring of spring constant 40 N/m from x = 0.20ms bo o-/ /xi(pul00wn m to 0.25 m? (Assume the unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring con814/xryt w jgrstant of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an additionalwg1x t/48yjr r 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 fromu+e uzr 9 x s8k4+cbiok-;kc.+m4djao the top of a 50-m high slope. What is the speed of the slier onk. j+zk9s edu4+b4kuim +8- r;ocxcao 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 karuf. ;-+vi*: ee eswfg, pushes 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 in elevateu+ e-f;fs:vr* iwa.eion?

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 friop2r:o-4vgq ja tm a9uam7+k5ctionless inclined plane. At the bottom, it has a speed of 9.8+49mk:pov57ajo2 q trg ma -ua0 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, its popoqvb(+8so l0tential energy exactly equals its kinetic energy. How fast s+l0(oob8vp q 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, blasqrik4.ymj(k9 ts straight up from ground level with a kinetic energy of 40 J. At the exact to kkyqj9 irm.(4p 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 gro)9o8y-w 2ez ifeufqb (und with a kinetic energy of 220 J. At the highest point in its trajectory, its k-e9fbfi8q2 (ezyw) o uinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above the bottom of p rmc d+cr (egp*r 7c*rt7/6mna 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 /7t rr+cngrr*c67m* mpdcp( e 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 wit,cbfm4k n t3m)uzxm(yl1 auzr.i : p.;h a speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, wha:nub1)tac(xlp3zmm4r fizk; m y.. u,t 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 w qkpqnnn(0l )5ith a speed of 25 m/s (See Fig. 6-2). Neglect frict5kqqnn0(n )lpion, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the 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 ban1mkbosqn u 0fo /vv9o: nf/32ll 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 pulleda5 ot5 2xw*tu+7aho/ kb-gffu 30 cm away from the vertical axis and released from rest. What will be its speed at the bottom ofkhxfouafw7 -*/+ta5g u2b 5o t 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 hi;wtcb4wi* h znz/h/;2 2mfreq ts an initially uncompressed horizontal spring with spring constan ht;m//z n hf*wqzcw2b ;2rei4t 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 uz10 j,mlvlv. 8zaeq)for a red light. What work is done by the friction force qmejzz) 1vv,u0al.8l 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 surzjmi w annat)p9nn(99 vuo;93uxu6.bface is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming tonnj(nvp a)wn6;u9 i9.zu mobua939tx 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.9j m/zpto+gy;c -d nv2 It has 24 J of kinetic energy. The fricti2zody9+ t-/ npgcv;m jon 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 horizontally to a 2.0-kg mmwn yvuex/(vqw; y 7s,;jg58 fass 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 itsem;5y u/7j(w 8vsv;xng,f yq w 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 frl :j9c. 6 r /i60kfgloy9qqyz-ee(y olom the top of a 50-m high slope. If the work done by fric y09eklq.9rg(i/fol y:jly 6qec-6oz 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 4.0 m long and rises j(e2twx7 )c)r.lf bp b2.0 m. It requires 3200 J tr )wx(cb ebjpl2 .)7fof work to get the box to the 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 restey:;ohcl eq9vj(j av d1 8l,q0 at 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 ofjl;hy, dj(0q qlcov 1vaee8:9 the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, t7orp(s6dlv s5(l 0yland strikes the ground with a velocity of 7.00 m/s. What averpl0 oys 6dl57 vls(tr(age 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 energy when he runs up a flight of stairs 1i;iyh eryq0::uo12 qa 0.0-m high, in0:hie:q iyroa2; q1u y
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 tf*wiq0: p*6 3vtje:fv ,lg;y q5mteb to move an object with a constant velocity of 5.0 m/s. What power must be delivered to the o;3 mt: f tw6jf,y0t q5iplv:e*ge*vbqbject 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 hp6j q7otz kw34n/9bd wq = 74 q6tj94oz/3dqk w7wbn 6 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 rat:1gnhredx ax9j x3k; 7e of 500 W while riding. How much force does her f a g9njh1ex:3;rxkx7d oot push with when she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelera6s y(gvja b,3-lso*ittes from 0 to 25 m/s in 7.0 s. What is the average power delivered by the enginiys3-6s,jl( ovg*a bt e? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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