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

1#

What is the correct unit of work expressb8* mr xgqal89ed 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 nrz2 s* tli/7nhkvyob1ez8 ;7co 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 stationaryrwz55oz/*eq, enp 5li brick wall, the amount of work youpzz5n5i rq5ew,le* o/ 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 much wo 0x,2dfs naz+brk is being donnxf02,d z+s abe in holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horiz+v3;mzsehl xh ml 40fpg0zc8he:d :2iontally forward at a constant velocity carrying a 10-N objed0h+z:fm0e8; hhli p v2x3:sge4zlc mct, the amount 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 orig uzj+nkcq2k +nckp:6*inal position. If the total weight is 30 N, how +q kz6 ncun* kpj+c:k2much 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 e5v/fb.;s nyt 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.tz51:o hru-(wt u1jqj Compare the sign of the work done by gravity while the balt1jout(u1-h wr5q:j z l 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, repres5 kfwidwngr4j9c +78 uentswcd w75j4 +kfig9rnu8

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the worcaqf 7+b*kpomz1qcbpmk j /-69g 4 je.k done by the forcepqb4qo-a.kp7 ec/kj*+ f m9m c gb6z1j 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 kinetic enerf28 3m* mndmnqtosk+ b0 h/bv-gy

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 theu-1s+w7k p p cxgqf06v 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 objecy8 oj-g/1edr0ckh, lq t's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at twice the speyk t1sl. 5n/dxed of the car. Why5t/ xs .n1kldich 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 ca imiw,7iuj* +mr K, and car J has half the mass of car K. The kinetic energwi um+ ,i7j*imy 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 itsovxxm5g48 ro .m; m21bp0i xjv original speed. What is the ratio of the fi1 m8.gmbvpmjo5;o rx2 4x x0vinal 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 moving aa5 :mgw8hvnjy,-grrgm98v ca*:sa t 3t a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratrv,st a3 wmg:h88:a r*9vgynj gac5m-io 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-kpw : /nk*s+nlhg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force w/p: *kns+nhl, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a c:1h,k:glpzs29ra xte ertain distance on a straight, level road. If you had been traveling twice as fast, what distance:pa1x:9l ghrt2k, z se 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 in an elliptical orb06nrbm e+o990t ka-bhj6rtn mit. Neglecting any friction effects, what happens to the -9rb6m0t0oe+n t jrn bmka96h 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 priiy +4io, i7zeznciple.

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 hs)tlgn5ysqs .u/kl3 4ave 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 object wpdv nyl/5yb( t,:w ek:6v uf3bith four times the mass of the first if released from the same height. The potential energy of the second object compared to the fi /d6pb 35 f nykbu:vlv:y,t(ewrst 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 sunk7)r m-4x ,xxbvx (btretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potentiam urxxk74b(b n)x v-x,l 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 a4s d4f. ;cr/g pv8dmbdoh vda,,r1x 20dnt-yof a system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K,s2uxzpv4y )y xf7.z.j to its potential ener y.sfvzp7xx2y.j4z u )gy U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving up a5*si;)04ifs qe qy nma 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 objectz/7o c xpba:r, and a very heavy object are sliding with equal speeds along a level frictionless surface. They both sp7bz, x:or/c alide 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 6b+t0chsd k0g $m_{1}$ 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 conservaecns ,b)ua-ai rd; 0q8tion of mechanical energy for conservative forces.b,;e)rasu 8 qn 0a-idc

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;:hzd(oudt( cc d)9d -cjmm k7, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just :(7;)ktz(jdduhc dm -d 9omcc 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 i r)w)q-ufn;+pbrdh) and gains 30 J of kinetic energy. Do not ignore air resistan)p-q; w+)) rihfdurbnce. 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 potentiuos6k:d:n okafru j6a uq5*ab tk;n.l9w2+*hal energy. Do not ignore air resistance. How much kinetic energy did the bhjok:kd65;ann :k+bouf *9qtaluaw sur .6*2 all 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 ener:07 cqf 3fum;zmpyeyprl /*jutt60+rgy.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is;uhx, z6 uop1k

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 93b0az ,rti xvexpressed 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, whichj/5usoy 24p24 xlwarn 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 evp ckl7bp2..work in one-third the time. To do so, your power output must have.vpp 2l.ec bk7 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 ac1m.k f(dmbx b(celeration, 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 objezaf pkt8(fxy-+:m 49 f ouk+ryct weighs 90 N, how much -kf (ort8+a+f4x9m:y uzk p fywork 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 thlzspl 7f nn/+2e air a distance of 1.0 m, at a constant velocity of 0.50 m/s. Wh+ n27nlfspl/ zat is the work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward/aixk5 np *t7)xb r:wh3i4eoa with a constant force of 5500 N for a distance of 50)wox aib73: k/h*ein5pax t4r.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 uafj+ /n tczo3bdk)9s*9 qpxd7 pward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of the e 3x j 7kp*9sa +oczqt)bd/nfd9levator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with ale oo ).lqdt):6pe,cc constant force of 5500 N for a distance o:o .eqd o )6tcp,lle)cf 50.0 m. What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up alz100f;uets y4c *ky wnong a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp, 9+a5nldo) ytyb e ,s3oinclined 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 Saray5 q+u .gw63ivts 9aiah in a sled on an icy surface (assume no friction), with a force of 60.0 N at 69qw vi.+tas 5ayugi3 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 kmz5ebpcq-yia 6/* )j the force. The graph in Fig. 6-1 shows the force versus th56p-k/bi c ajz*qm )eye 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 o,:am x+ pwbz6n*bwiy* 7oae2g f the force. The graph in Fig. 6-1 shows the fob+26*zowg nxpa7*e b:a,wyim rce versus the object's position. Find 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 dirn3m8tyn/ je8h ya o+2gy*8ncg ection of the force. The graph in Fig. 6-1 shows the force versus the 2tme88yo n/+ g8c ygay*hn3jn 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 objecaq48,ap ;q klft in the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the objlaf ,a8;qpkq 4ect 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 (i0 b8bj5kzq6mc8 m( vdiho0n: pnitially at rest) across a 10 m level surface. What is tvh zm0(6n: 0kqdmcojb5i8 8pb he final kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initi ww(bw.na 6bd9*j;fjpally at rest) across a 10 m level surface. What is the final speed of the c6 *p(; 9d .bwjbnawfjwart?

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 j g3 suy/ kpd4d1ib07nto stop the4s dbp kjg/n30u d7i1y 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 af p,:w6 dv3zjut 25 m/s, what distance is required to stop a car moving at 50 m/s under the p ,jvwu3dz6f: 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 exertinsfrih)y6h r0k5 ;/pgj g a force of 20 N over a distance of 5.0 cm. With what speedrji6r;hhs y)gk05fp/ 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 80,9rsdao 3a5vdw6qg sr 2ddlx.v j)e3, N and a vertical component of 60 N. The force is applied to a box which rests on a level fricti.gvsorw 6d q32esd,a d ad395vl xj,r)onless 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 of hay, striking th, w+8b(jf qdkae hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stoppinjwakb+(q, d8f g 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 aby j wp0og5;i,ad, -jquove a floor to a height of 1pd aqw- u,o,0jjgi 5;y3.0 m above the floor. What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m 4yx9, laz)kr9ajr r 3olong and rises 2.0 m. If the plane is frictionless, how much worky ljox9) ar4a3zk ,rr9 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;zgwn4 u w:+zsmjj3:.8dlxdl spring, causes the spring to stretch 2.0 cm. What is the spring consu;+gll w 3jdxdsjmwn ::zz4.8tant?

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

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

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. How much potentiadany-g (gs*,747i(pfu z hmyq l energy does it store, when stretched by 1.0 cm?(g m 7dhn( gyza7q-,*iyp4sfu

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 compng;iyo/ *9x o;ma*p5sm deq xd* 2c.axress an initially uncompressed spring with a spring constipx gx *omq;eo / y*md.s a5dn2;c9xa*ant 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 spring constant h: :omv:q-lto 40 N/m from x = 0.20 m to 0.25 m? (A v:hm:q -olo:tssume 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 consta1 vx;szip;k 9lnt of 15 N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an additional 4.0 cmk;pl9sx; izv 1?

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 a9o10wxg5 a/1yyztc m rest from the top of a 50-m high slope. What is the speed of the slier on reaching th/ g1oc5z 0yxm9ta1 waye bottom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top ofsr vd,-iq4v:p4b-epp a hill with an initial speed of 4.0 m/s. Neglecting friction, how devp :p ,--qpv4 ris4bfast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the bottom, it haf s1 wdub*5yk+s a speed of 9.80 uyw5 ds1b+kf* 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 thnfq8 m7.3w.kwa0l heje floor, its potential enerqj 0ae7wfl8.kn3w.hmgy 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, blasts straight up froojjp aypi9j45 yum2- 8bgz*0 xm ground level with a kinetic energy of 40 J. At the exact top of its trajectory, i p92pjomyx -u0j b*ajizg8y 54ts 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 leavesw4pu t6j;ub y t1gc lts//nn ca/16rf0 the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its w /;r4n1u y /b up0snlttfctc661 ajg/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 a dip rrfxv 6z*m*lna--db8j b8l-l (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 of th8l-zma d-8x6fr j b *l*bv-lnre 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 abov9gp1p a*ku1t xvz,.yge the bottom of a dip (See Fig. 6-2). Neglect frict1x9 . ,pag*1pukgtz vyion, 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 8ahx(h(v u6oh0;pe8tkk w9 vaa dip with a speed of 25 m/s (See Fig. 6-2).(9ux08(;a8 vtpoeh6 hw kvakh Neglect friction, 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 bak* ir,fx* ap-ell 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 pulled0kvvbl+f*h 5(6xsis w 30 cm away from the vertical axis and released from f x+vishw 5bsl06v(*k rest. What will be its speed at the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed h6zb qr,o/mg3d*qy3o t orizontal spring with spring constant*/3,myg qzrqb3o od6 t 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 dowsw((ntk e(q k-)m1okc p37oxen her 2000 kg car to stop for a red light. What work is done by the friction force against the wheels?)7(soxketokmq3p e(w n-c(k1

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 is ch7iop9: a gh9z0 *:eadt(isn50.0 N. If the initial speed of thes o: d*z(ta7 ipc9n0e:ihg9ah object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rougf 98 .mx)o o/,xvwumg;8uyv lh/aw( snh, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. How far will it gno/8; 8ulwxmv(uf.w v)oy9x,m h a/sslide?

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 surface.ltvnpwo2,xns f1 :q :3 The coefficient of kinetic friction between the man:wtson v2: 3x pqf1,lss 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 i dm2s1etafevf7z : uhu,n;0/ rest from the top of a 50-m high slope. If the work done by frictise2 t7; 1m nf, ehzdu0v/uf:iaon 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 lwgrrr*0 s cxd07.km x*ong and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. sx g7c0*0*rdmrwxrk .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 top of a plane inclined at 2j.xz o 00wd 66ykz/rmm0e above horizontal. The coefficient of kinetic friction between thezrdwz6 ./yo 06jmkxm0 mass and 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 height / hyxps;w7o.wof 10.0 m, and strikes the ground with a velocity of 7.00 m/s. What average force o/wswp o.y7 hx;f 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 o1dz 6z1(j oawygvi 9:kf stairs 10.0-g9zzo11ak: d(j6vy iwm 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 mo9o n9wjo1q y6nve an object with a constant velocity of 5.0 m/s. What power must be deliver 69j o9yn1qonwed 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 use cn6y2x+2oe uxtu07bz d by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 7u76t0ey n z+bo2c u2xx46 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 forctjidm)+v79q1 (( qsufz jz o,ke does her fouizt7) +fj1 qmzv,kd(9 sj q(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 accelerates from 0 to 25 m/s in 7.0 s. Whaau* 2n *c3rrp0ddz*6thx ++ sieim /nlt is the average power delivered by the engir0ht ms2+e/**ndd *nir3a z+pcx6il u ne? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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