Physics Unit6: Work and Energy - 51fly国际课程 (51fly.win)

1#

What is the correct uzsap;ujbx*u sr-*9 (3;.esetrvw q7 dnit of work expressed in SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on af1 qy*1q*nll qnja g2y.gw14p system if there is no motion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard aga qf- oo p/nwvy9lqco,r)7;u5uinst a stationary brick wall, the amount of work you do)yo95oq q ;pc,/wuvu o f-lr7n

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 heumuyt0)l9vhd;w*o /c*zv1 elld there. How much work is being done in holding the box in th uv* ou ;*01c9wmdvy)/zle htlis 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 forw(xx :hh5w,k yeihs0ot* y,j/oard at a constant velocity carrying a 10-N object, the amou koyixxt5 *syh:e,j0,(h owh/nt 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 jvpl( ;nge4 rx-08ipqwo t9/, q*htuvits original position. If the total weight is 30 Ni0 ut x-v9 h,q(jnrl/e;qto*w4gv p8p , how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do work on ktht-z3 og*5 vthe 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 straigh99 ka ici0tq -ew-7vtdt up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work dotk w c99e-td -i7av0iqne 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 p;l zy (,dk ;yatcvv px,080fcyosition (F vs. x) graph, represents v (0ycpyx0vdc,ky,z8 l;;tfa

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 workghg/ 2h)/w leol4q0:q bat5ed done by the:g/ola54e l g2b0t)/h qqh ewd 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 an object is positive, then4f 2a4be4j zstvw0kl3 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 negative, then the object's kinetico(ub /kvye501rg;eaid 4x7 l q 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 kinj 5 of uu1vc/47-wmjgnetic 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 ofvn02xbf sw )u4 the car. Which stf bsw0v)4 2xnuatement 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 4qzuy,6ftm w4 bnw;o(3b;q kf J has half the mass of car K. The kinetic eneryuo4w3z f6mqb f ;;n4w,(bkqt gy 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 with8cbg.r g35lfr;b2 /:b bnzi jb half of its original speed. What is the ratj 5lc 3ibr.fb gbbr:2zg/bn8; io of the 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 moving at a speed of 5 m x2b(qn1c h/w e,vp+mo/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's ma(wm,n+ pb/1o2ve x hcqss?

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.4y,vw1 ;nxalx,fj xdty;/)99 ucwyr p A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same ,tua y yyxvp19;wxlj,cnx 4;f)d r9/ wconstant 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 your car in a pan-a y9 kafn 8caucdszuj5+7e5: ic, and skid a certain distance on a straight, level road. If you had been travelingfs 59u+j7u5cz:k8 e d-yaaa nc twice as fast, what distance would the car have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

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

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an evfy+vlhfq6 y m(0 7j+mlliptical orbit. Neglecting any friction effects, what happens to the planet's jm+y m(y f flv+h76q0vkinetic 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 prsi;c j hqd:-f l13;tckinciple.

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?oh6phmu (m)p0

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 vwa;gu) fhe *3height h above the ground. A second object with four times theh v3faugw*);e mass of the first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end ofrhr,tqecmncs +*-buy k 5e:8: a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potehnk*:,e -e y q8+ur cm5srt:cbntial 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 ener0 agr)lcl- v.27uaam0x1mytegy 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 vt);ve e+m9 putree. Compare its kinetic energy K, to its potential enerevv) ;pu9tem +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 drivingj3zy780bhtl)lb x j2 a 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 slij 6)bb+ogle9n ding with equal speeds along a lj+)9 eoblb6 gnevel frictionless surface. They 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 yz. f:kxyx d2*kigz1lk sl88.$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical energy fssw5-u 1( l0j2 rafneuor conservative forcesu2-e1rua(s 5f0 wljsn.

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 frict0vv-m wzx,ycxrrvk:s-+ c 6z.ion is present), to the ground below. How does the kinetic energy (K) just beforevk+0v rwrx:xmc-cy,6.-z sv z 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 distvs x2*h o(bhzf9 .fm*wance and gains 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the bw xzm2svf*(h *ho.b9fall 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 potenti)/owyd gsuf 1ic*:.(tb6 dgcpra 15kx al energy. Do nogu 1/cdra o)*:df6ibws1tc y.xg5(kpt ignore air resistance. 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 conservam j4kq2ttx 49wirb to;; ;g5ixt f/0mction of energy.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is. k 6(j-hq2l wqaqvkp/(8lr dn

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 +z5 d8ytent60 (wcpm wbqoo;+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 uprlv).kb jr;, nit 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 timc9,sqnh(x/ott p3 uh.es the work in one-third the time. To do so, your power output must have huos xt9np3q,ht/. c(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 acceleration, the car's engine mus*c6fzckr 0)vf.ax5 *yseuyn *2u li l.t

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 v66 gmfmeuzf:z 4 s5j vveix:59ertically 2.0 m and held there. If the object weighs 90 N, how much work was d5svm6ze:6fx 9f4em:i vju5 gzone 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 physic 8u29q(yaee-*fqq iqas book up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done by the weight of the boo q eu2qyqa-*a89qif e(k?

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 wit2gg08 g4wsdo sh a constant force of 5500 N for a distance g4ogsg2 0w8sd of 50.0 m. What is the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for 9n8caalsqy orw-k:69qs5;z c a distance of 50.0 m. What is the work dqasqca8c9zr9sn oy:-k;6l w5one 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 n de(4qr +sxn;., blxb 0aoi4zpulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the elevat4zq0b n;e.dib+s(oxn ar,4lxor?

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 upwem ; hnie1;mne,i-x3 along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ram3 +zjlynj0(ua p, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy sur 6 cfk y73e9 xxwfg7)au+de/bs /caky6face (assume no friction), with a force of 60guc 76) y // a6 byfxxk9+sc7ewfaked3.0 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 ini. vzb+w;ppj+ the direction of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when pp+iv+; z.wbjthe object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Thhcg5p0m+ ieg8 e graph in Fig. 6-1 shows the fp+mgg ch5 0ei8orce 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 direction of the force.ez .4mhlbehd dmq; 39* The graph in Fig. 6-1 shows the fo.mh94 ;meqd*d ze3l hbrce 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 of the fc fk8)7i3msvlb q5j(fi,yj- jorce. The graph in Fig. 6-1 shows the force versus the object's position. Find tj7jbv5mcfskji (3-qy )f il8, he 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 cart (initially at jnx/jbce99 pks1wj2l, rml 9+r/3px e rest) across a 10 m level surface. What is the fi bmj ,wl3ern299j/x ejp l9sx1rp ck/+nal 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 movw5a.mwoaozn1tbtr -8((zvt 6 e a 55-kg cart (initially at rest) across a 10 -wt zo8va ozmtb.w16an t ((5rm level surface. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much work is required 56 bigeexbd h5yn9j,.h) t/gvto stox6 tn5h5h bde)i9j, ./ygbe vgp the mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car init h4ih7 .wk gk4 imynib7c2qe 4ye),bi1ially moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same conm 4 qk2b4w 7kiy.,ih bgc nei7yihe41)dition?

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 mgrab6dh bx;l+**f n010-g dart. It is cocked by exerting a force ofabmgbx +*ld6*r;hn0f 20 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 horizontal component of 80 N and a vertical component of 60/ksfob+;dm7yl u4xgma,m m )nx wi6; - N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's i 7kn mx )ul dabg64/;mom m-s;wyx+,ffinal 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 the hay e2shhb ,r76dg with a velocity of 60 m/s. It penetrates a depthb, hd7hrs6 eg2 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 above a floor to a hemvzr+nlm5 ,xn:oc 17 bight of 13.0 m above the floor. What is the change in gravitational polm5b+7,rmxc nv n:oz 1tential 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 rise i r;bo8u.cre;1 c7puvs 2.0 m. If the plane is frictionless, how much work was d;ru7 b8.pio1r cveu;cone 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, causx iw*6bqz*z kg2c*fk9es the spring to stretch 2.0 cm. What is the spri 6 *xqfg*ik2wc* 9bzzkng 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. How much potentikjy(u/.q)hvz , mcv6 :iq mnb(al eneh(i/ mq)vq(6 ujk:vb,nyzc m .rgy does 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 v83 fg3q on(o9xv+w/ rgnol9td6 ym4hcompress an initially uncompressed spring with a spring constant of 25 N/m by 10 cmn6vl3 +(q g4 8wf d39xvoohg9rty/omn.

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 sp6z im5 b5njyc:ring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched pos5n:y5 cbm j6ziition is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant oh.w:gfowp s z y;n7;j6vn(;eo f 15 N/m is initially compressed by 3.0 cm. How muc(;ozp f6;w h og;js7yvwen.n: h work is required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slopej. i :ibunbwl8;f3r7u . What is the speed of the slier on reaching the bottom of the slope? (Ni.ruiw3j8un:f bb;l7eglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial speed of 4.x3 (qf c x6fa4shfd)e,f4lk4f0 m/s. Neglec)e44f3k6( cf shfl4a fxx fqd,ting friction, how fast 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,zi53ee-y*v tq9 l 51g:inedc wh ;.xmj it has a speed of 9.80 m/s. What is the vertical height nm g1d jh5l.zy ee3wqx9*-5 iivte:;c 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 thbd itvd podg* .q-5:o *k53qnae floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic enq3 -dpoo* ng dt5iv.qkb5d:a *ergy. 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 strsjeejc h,5 qjlh * c81y+;,laraight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanicalyj8h,je +ar q 5;l,je1cs l*hc 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 ground with 9ki,,i xae p+x* oge9vg ic: qt7/ya3ra kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy ii e c+g7kv:g* /3e9i ,9arayxtxi,pqo s 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 poi ugvwyyl6 :0+v lnmwt1 :xwy4yyen/43 nt 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the6w1+ x:t 0y4lgwn4y3/eyv wy :nym lvu next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster sta9.zt7pcg tt9hz7:d vrw og+- irts with a speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of thtgo7it9rdw g -pz+zv7c :.th9 e 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 30q .l+um4k/oe/: g yveb m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, b. +myq/o4guele:kv/ which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottom of its swing (a4yt -evv4 .azpoint

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and re1nib:j20nd n jleased from rest. nb:dn120j j inWhat 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 ism 5b2;skm js,nitially uncompressed horizontal spring withb;jk2s,5 smms spring constant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slows down her 2000 kg car to stbmu5/wa .: tetop for a red light. What.e:ta 5uw/mt b work is done by the friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and biff:da0n xf,)u rcn(7vd 6i 4a horizontal surface is 50 4v70ax,r 6d(i fib:d)fnucnf.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It ha1kd+gf vje;d7lcbrm5 b 83wx( k ai//ls 24 J of kinetic energy. The friction force on it is a constant 0.50/8la /kl;(3i+x 7bjkmbdcw er5 g1vd f 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 levtxoi s 7e+q-:nel surface. The coefficient of kinetic friction between the mass and the surface +s- x 7qnt:eiois 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 torv7j n-6sb2tzp of a 50-m high slope. If the work ds-b nz 67tvrj2one by friction 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 4.09 jqvxg72xso*7qdu0l m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on th xs9ud72 0goljqxv7q*e 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 20e -row a99:g vi uu84fiaabove horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the masfr8 :uu49 a9iowaig-v s 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 7r8u tt zun9p rnn /s3)q3qqg9of 10.0 m, and strikes the ground with a velocity of 7rrn389sgu z /)u7q3nqqp tn9t.00 m/s. What average 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 ui-ktsz6*egvcl5cw+4 p a flight of stairs 10.0-m high, i6ivkze-cc5 w *tgs l+4n
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 cufc 6wsxwo1(5onstant velocity of 5.0 m/s. What power must be deliveruc 1f wx5(ws6oed 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 h2 ;w /pyw6ca 7hzht,b: )hrckruns for 1.0 hr? (1 hp = 746 W:6pc,rcw2kt;hbh w /7a)zy hh)

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 8i-vsg.r5d vq d)*)6anp* rspu ks5jp500 W while riding. How much force does her foot push with when she dkis6))*jp .a-*u8vg r vs5nrqppd5sis 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 25d8w36m c,esukaq47 uf m/s in 7.0 s. What is the average power delivered by 3s eucmf4,k8 wu76a qdthe engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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