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

1#

What is the correct unit of work expressed in SI unhi)ql5.gj -oq+cnq2 r.-up qgou v uy-p27 *qlits?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no mot5hwalx e x+h94ion?

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 )y (+4zvz3 up tqsw0b2eik6do a stationary brick wall, the amount of work you v)ydwzo3 eu (p0t4iq+ s6bzk2do

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 lifu9/ euj/zl q rdpy;xps7d.z( 8ted 2.0 m vertically and is being held there. How much work is being doned87 zq9;d.euuyx (/ z rp/slpj 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 horizontally forward at a constant velocity +/laxw dkf w:/ty..obcarrying a 10-N object, the amount of work you dody.low/x.bkt/a w : f+ 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 ;nzik 1m/x5y treturned to its original position. If the total weight is 30 N, how much work wasnmk5z /x ;t1yi 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 a+s4 8yiswjzy f4h16 tqipa5 c(n 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 the sign ah2r4knt3;:lf clhn4 of the work done by gravity while the balf3kl:c44 h;nt 2hrna ll 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 56cja+c, sn9: gvo wuxvs. x) graph, represents,s xcn+cw: v5jg9 ao6u

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 veri2 gniw5g e19bsus position (F vs. x), what represents the work done by the force F 19i5nwe2 gigb?

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 an4pv9 siobb62ke4u ;r p 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 object4xpc+t n) fiz;9gufm + is negative, 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 oavl:2p uau6m.xe y8)u n an object is 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 a7cb:w /ngjhceb.u afy,t7x,( :y lr2x car, and is moving at twice the speed of the car. Which statement is true a277,trjacf (e :.bbgx ,: yuyx ln/hcwbout 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 carru5t 3 2nb1vzx+3zr )7sggukx K. The kinetic energy of car J, compared to carz3)kz s1 vxux5r3 gr2u7b +gtn 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 th0- 3c6 otc-9eciorpjjg9 2zwith half of its original speed. What is the ratio of the final kinetic energy to the ini3tocto c9r0j- j 2ghceizp9-6tial 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 spee27kz9lbw k3lr)mc ,q ud of 5 m/s. If both objects have the same kinetic energy, what is the ratio of t3 k7mwc2lqr)bzl ,k 9uhe brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg mass is moving wil3y; bi a2 cx09 7auj+dp2kpa0fq*fp kth speed 4.0 m/s. Both objects encounter the same constan 0 acp2f+ kp7apqyk9;*3 ial0f ub2xdjt 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 yo mrqe4bsxfh r874z(xp 96,*hah su. yxur car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice he xhaup*y6bsxs(.8 hf , rqr7x m4z94as 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 m87f s i1d7nf +1)bby9ngqytz uass orbits the Sun in an elliptical orbit. Neglecting any friction effects, what haizfy8 fq71ys97bdu bn+ tn)1g ppens 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 prin,s3o1u ,fe6mkzb t ml/ciple.

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 potentimhdgn 8mk) (*erxw,a 8al 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 3y(nv5uu+swb5kbe8 a(vmz h0 ground. A second object with four times the mass of the first if released from the sabm+v(vbk 5a ywh3e0z (5u8nusme height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring caus (scj y0yql.+t/x ve9jes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring will beleyx. q0v+j/y 9j s(tc

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a syr h,vw (ljv)6dstem

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. Comakd1yp5y lx.-pare its kinetic energy K, to its potential ener1xydap ky5-l.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 o pg/ln:q7f hj0f a car driving 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 sliding with equal speeds8 l:(-c u-vkifztbc -p along a level frictionless surface. They bot -8c(kf:-p ictvzub-lh 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 1 p)m2qp/x-m eii moi,4/odj*apz+lb$m_{1}$ 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 ofgk l2u:9yefa4:h3pmj d5n* vn mechanical energy for conservative forceslk3n 4egdhn: m* vyfaj95u2: p.

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 1gol1p1mj+mawb1) kqnmd+1h the air (air friction is present), to the ground below. wg 111+ kmladj 1npbqom+h1)m 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 gaio ()gbcb z*vg0ns 30 J of kinetic energy. Do not ignore air resistance. How much gravitational potential energy did the b(o)z v0bcggb* all 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 lot9k;l*wpwr( eln1r 4a(jsk b+aw (c1k ses 30 J of gravitational potential energy. Do not ignore air resi jrwa 94n l;(wwk1e(t1k+*alk rcpbs(stance. 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 conservatg rdr zrjpq/g,*n gcb 3+2v,6g.+zsbp ion 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 isx* 8(jixg(e5t4 zelir

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 un +5isyp2 0sdfvh)r8qfcjpk 7x8p6.k eit 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 unj njs67b0zgemv 5c8k+w4v+t qit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in one-third thp 3i8mu3-cu ixe time. To do so, your power oip xc3um-83 uiutput 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 acceleration, the car's ennwz zcw2bl+siq wy602 )7y)r1 u y6jibgine 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 thm+tfnt77i b)le y;tpn*v ea,0ere. If the object weighs 90 N, tv7m i*t7tf0 e;n),aepbynl+ how much 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, 0zoq7.+ jpmnec:k6mxmr.zn-b( k. w y at a constant velocity of 0.50 m/s. What is the work done by the weight of the :m n+ oqcpe(j -. z.kkmw607.r xybnmzbook?

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:07cyfm91)bo sv l mtzn cp2o- for a distance of 50.0 m. What is the work d:mcvoo 2tp0nc1m7-9)bsz yflone 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 upwardu, 5lurfb yrja7 a 1vvrd9k-0( with a constant force of 5500 N for a distance of 507 bru (1vjkal-d f90yu5v,rar .0 m. What is the work done by the weight of the elevator?

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

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

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

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

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is xl3py61k o+ikpulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the net work done on the e6okxp3ly i1+ klevator?

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 along a ; /.7c sg)no h7dhmyk:feqx .n$37^{\circ}$ 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 doy//t q-vo.efj-hi60 wmd r b0nh ,ypz3mikl;9wn a ramp, inclined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sledrpv2t v)o n/ap+-.w2*vb xyu9s.f ncg on an icy surface (assume no friction), with a force- p *..tnfvgc2v9 up r2xyvba+/sno )w 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 t:o anjn jqtdj:0c+5 7uhe direction of the force. The graph in Fig. 6-1 shows the force versj5n0jacn:7 o+duj : tqus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Th 4m /(5 .f/zovu,jjpybw2uioxe graph in Fig. 6-1 shows the force versus the objw5f z4 (ivox/ 2.j,oy /bupumject'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. The graph in F ;bmv75sbb6 etd,(.jj.5nxk ; s evbkxig. 6-1 shows the force versus the jx;.e v7stbjx vn5b5d,bk ;me6.kb s( object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The pegpq +w ;xb31jcx8 4 xayqjf00.fdp.graph in Fig. 6-1 shows thc 03+fw8 1pqx.xjqjdybp .;0faxp4 gee force versus the object'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 cai7+ egq cr p6ur.b0mt sz4-iz9rt (initially at rest) across a 10 m level surface. What is the final kineticsrqc74 grm. z i9u+tz-0iep6b 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*qd xdfy4kg1.e.3 xds;sohv . a 55-kg cart (initially at rest) across a 1des 1*kg;hs. .o3vxyqdxf .d40 m 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 wott (f24 mnzn*nw-x 3dw8qvtt 2rk is required to stop th-nvzqtt24 *fmn3 dnx2( w w8tte 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 mv)ien)z5hp)dqw3 j 2 m/s, what distance is required t23)q))5zv h dnwpimjeo stop a car moving 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 propeqwm: nzd1;dl 7ls a 10-g dart. It is cocked by exerting a force of 20 N over a dista:md n7dz1wl;qnce 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 componowl 4th7py puiw+)7n .ent of 60 N. The force is applied to a box which rests on a level frictionless floor. The cart starts from rest, and wlt4+y u7ppwn7i ) o.hmoves 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 horiztbrgi xc 15v2tk x(o51ontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stoppi o1xxt2kr1vgit5 cb(5ng 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 jyj tr n lhds+:2*98ogabove a floor to a height of 13.0 m above the floor. What is the change in gravitational potential energ8 r:sj*2n9dtgl ojyh+ y?

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 anr:s zc*q5arr(yv bxb,pyr 9 c9t1v65yd rises 2.0 m. 9y1 ca5v:b65sqr pb9ryv* (,czxrry tIf the plane is frictionless, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to stretch 2.0 cm. Wha.t1tksx1 sg .dt is the spring constant1 xtg.ks.std1?

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 byc1 )qhe5hxdq 1 a spring constant of 60 N/m. How much potential energy does ixeqc1hhd)5 q 1t 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 tjg3;dwroqdp fr-l+ 8 t )a-bu,o compress an initially uncompressed spring with a spring constant of3 u-q,j+r ba8ogfl drdp-)wt; 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 spn ;9b5z d h7+uf79kp+ophzayr6t wk3y ring of spring constant 40 N/m from x = 0.20 m to 0.25 m? w+y ynkfph5pb937;h k9ozr 6 ztd +7ua(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 constant of 15 N/m is initially compressx+6ddr cf9-rp k/v,u0ktif v1ed by 3.0 cm. How much work is required kx9uc rtidvp /fv,1dfk 0r6-+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 frh 4o mvfaj09orw 0)wyjo/-.meom rest from the top of a 50-m high slope. What is the speed of the skier on reaching the bottom of the slope? (neglhm)oe oo90mar0wvjw yj /-.4fect friction)

A. 22 m/s

B. 31 m/s

C. 38 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, pushesb/pl5cmzrs: 0 o 7qa(u0a+ulf1ce5 yd off the top of a hill with an initial speed of 4.0 m/s. Neglecting friubf1pzu /7d qc0s5( cye5ao: la0+ mrlction, 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, it 4xlod4uco9ej whud*01agi 2 jw27ja6has a speed of 9.80 2 a9*jej0awgx ou27 dhjuil4w 4odc16m/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 k0 oobmp p k99;a90w-sodpsv( 0.70 m above the floor, its potential energy exactly equals its o-sk99opvk0bwap mo d s9(; p0kinetic 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 from ground level with a kinef em +kek0.xa7uj :/mptic energy of 40 J. At the exact top of its trajectory, i/7fk0pm ux:m j+e.eak ts 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 ground with,gleof26d en ) 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 lae 6long,2 )fdeunch 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 botto/g dfv l;f,da.m of a dip (See Fig.g f;da vl.f,d/ 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 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 ayzt kxq y.+b 774/elzof 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 theqa+l7z4tyx /zk.7 bye 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 poi -uhzv*r+ox)vn30oi,c 5kyyi nt 30 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)ooi+k vn i *zvr c-y5,0y3uxh the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the mw i o03zce+h:l.k(u:cfpj0i 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 2-kg pendulum of length 50 cm is pulled 0.25 m away from tse g0i/x f;cyq*4,dh jhe vertical axis and released y xg df,4hi0/;sjecq* from rest. What will be its speed at the bottom of its swing?

A. 0.344 m/s

B. 0.917 m/s

C. 1.375 m/s

D. 1.146 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 uncompre+jssav -b/uk 0ssed horizontal spring wa0sb/u s v-+jkith 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, sj j2zxd ;cv/z9z (mvm67e tt7llows down her 2000 kg car to stop for a red light. What work is done by the friction tjvvdxzt 9(;7czm72z 6jlm/ e force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a.yvnr1l:(w fp horizontal surface is 50.0 N. If the initial speed of the lf. 1wrypn :(vobject 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 sakze8+ +sn8icz,tusf4i,m oz0jl5d. urface. It has 24 J of kinetic energy. The friction force on it is a constant 0+k0ztf zjs, ,di+uica. 58eol z84snm.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 horizonzce9p (+1 kyizx vw.g1tally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distkz1z (9+ ce.ywgvi1xpance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the top of a 50-m high slope. If the w. zjmk xr);ys++nl: naork dks:x z; nr.m ajl)++ynone by friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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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 risesd -/lwt /z m20s4g59 hqyfttsd 2.0 m. It requires 3200 J of work to get the box to the top of the planelwdtz9mg/5f s2sq-y t0/dth 4. 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 :curv)y)fyf ) inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?ff) y:)rc) uyv

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, and strikes the groq oqj lw;r- 1lul.s+x+und with a velocity of 7.00 m/s. What average force of air friction acts on it as it;lw.+- olqlu+qsj1r x 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 energyf , (rgl zw9: gsvh*us6s;zrt, when he runs up a flight of stairs 10.0-m high gv9,s hgsz6u z s;w*l(tfrr:,, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocity of 5.0 m/s. Wh h3 p:jo2p9sehat power must be delivered to the object by the fe3 9jp2oph :shorce?

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 us+p- -p8 7 swffziakz qym/n2d8dz;mz, ed by a 1.0 hp motor that runs for 1.0 hr? (1 hp = 7/ msmz-7iwa2;kd8f 8yf zzdp n+p,zq- 46 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 whil- 31zcde*hxxu e riding. How much force does her foot push with when she is travz dh ec31*xx-ueling 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 08i6 rbjhbro1: to 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 hpjibrbr ho8: 61 = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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71	72	73	74	75	76	77	78	79	80
81	82	83	84	85	86	87	88	89	90
91	92	93	94	95