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

1#

What is the correct unit of work expressed in SI w) ws:ti)) fhf3znv. nunits?

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 d/cdq 13v eti2o i1,6ls r z,wvl9yg4cif 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 against a stationaruykszno /jlfv- v -03+y brick wall, the amount of work you do oknuzs/ 3l-f0v+ -yjv

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;r d7e v;tiu;a work is being done in holding t;d7eiuta ;; vrhe 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 carrying (tpmot hfa,7p2)hk8 6pzgrc1 a 10-N objectpzp,68t 2( )cg fm1htohrakp7, 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 ve9otsygs :,eq* rtically 3.0 m then returned to its original position. If the total weight is 30 N, how much work was d:,s t o*e9sqygone?

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 o4*t3t hpixepsbn9zg58oc , x8is l.y/ bject do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign of the work done by gravr)(-xto(pd yz ity while t o)(y-xdpr( zthe ball goes up with the sign of the work done by gravity while it goes down.

A. Work is + on the way up and + on the way down.

B. Work is + on the way up and - on the way down.

C. Work is - on the way up and + on the way down.

D. Work is - on the way up and - on the way down.

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the cub z2b;wxy1 :otrve, on a Force versus position (F vs. x) graph, represents2ob wyx1t :z;b

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what repvkwmsbk5(:wab 9) g(rresents the work done by th g)k( bw mb(r:k5wvas9e 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, then the object's kin4kl84yka lb)/x /b*7hnx a e oar(rf)o6sqv8metic 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 kiz t0bq00z; jd s3ff9janetic 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 kinetia x l,mt*(m;cve qx5/wc 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 abi: *ho 1ndi91(gxnwi s much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy(xingn*d11 oh9: ii bw 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:*pjg 4ngkb y a9ar heww7l.r8bstr-5in 5n,2 mass of car K. The kinetic energy of car J, compnwnr5j:8elrb2g, 7a4 k p sg-wr ab*5.tynhi 9ared 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 bhwlqyh(4 v:i :ack with half of its original speed. What is the ratio of the flqh:v w4y: ih(inal 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 mxt9lzmyg .r;h3g8rt tx(6k1z /s. If both objects have the same kinetic energy, what is the ratio of the brick's(x6rg t zk8h9xt;gmry1z. t3l 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 spedr8iu / mx;f/r 4e7yr7cdgc*bed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stop //uecd7bd f y;x7*gcm 8r4rirping?

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 xcq(8zq gx.6fl csu8* a certain distance on a straight, level road. If you had been traveling twice as fast, what distang (6x x8 qsuc*q8cfz.lce 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 orb,4gewd(fys bs j ,8.upit. Neglecting any friction effects, what happens to the plany(sfw4dbgjes8,p u, . et'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 principle. nasbp2-8 n-l05kof vi

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 c )glqyf (rmee y3,3v6energy?

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 res /:gylpxx:pelbkge:6p)je2 . t a height h above the ground. A second object with four times the mass of the first if released fro):p/l:xj le2:gpe beg.6kxypm the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring cau ore1j4a qq;a(ses it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential jr oe;aqq (14aenergy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a syste.qss:zg) tsu8jela1,+j 2jpi m

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. .v)weiu ayre-n;0p hyj+*:w w Compare its kinetic energy K, to its potential energ:* h wwyu)n ja0+-wrip.y vee;y U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving up a hil8r4,vnku(ejq3frk)04fgw nnf. ja7x l.

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/q ku/((g/r/n tfdiv i sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Wf(ut i/n(/i/gdqkvr/ hich 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 bzk6(g apj55 h$m_{1}$ 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 mechanic tch zsev+qa/e/vp v)0dg c85,al energy for conservative forcest/cgv ze5v+/ scav8 d)pq0eh,.

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 t7 )bpjtjsu jh -8jr/:nhe air (air friction is present), to the ground below. How does the kinetic energy (K) juj )rupbjh s:-j/n78jt st before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetpu6,:u8e 6g4fg; gnga byppi;ic energy. Do not ignore air refpn8 4yigaugpgp ,b6 :6eg;; usistance. 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 30m)q)+2g y0 lavxf*qhsz pu7+h J of gravitational potential energy. Do not ignore air resistance. How much kin uqamsl*xp)0zf yq +hg+)v 27hetic 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 conservat u7,p1v4m97 4zwwkvp p r1wjqezk/*74zjskzeion 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+ka0ttych2uxsw0t3 kk ,r /8y

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 expressed in SIi.1 wbom:+kk1rr pq)p units?

A. $kg m/s^2$

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

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

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

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit of power j/u/)pc w4lse?

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 di+ktv kw-jga32tb v -l0d 3 times the work in one-third the time. To do so, your power output must have w kbg0t-lkv2at3j-v+ 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 en ga0yw 1oi7suua+yhnua7 0.nx rck;3(gine 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 x-nx 27gne4x: h:loxq held there. If the object weighs 90 N, how muxlxnh:n qe 24:7o-xxgch 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 physics6h+h; 2vip wha 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 book?pvhhhi a2+6 ;w

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 isho*lik7o;gr44pdqy, pulled upward with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the 550*o,l 7r4 ;kiyqdohp4g0 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 wit 4n+3kdh dd0gdh a constant force of 5500 N for a distancendg4dkd0d h3+ of 50.0 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 pulled upward with a constant force ofg7(* - jq yavuyu0rx-f 5500 N for a distance of 50.0 m. What is the net work done on theuyq0 v7yj*rfgu(a - -x 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 i:yr za7 (o7o5 3:oozftn-nuv6.0 m up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp, inclinjjfq1e:i71 (rs43 8j )ri1khb y gelfced 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 S2+ 9 jgu(ctzbt-,p pp jh7jtp;g0vv( jarah in a sled on an icy surface (assume no friction), with a force of 60.0 N at an angb+j;gu( t(tp ,v90vjjppcp-7h2jtz g le 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 the force. The graph in Fig. 6-1 663)bjk xul em+xvri7upx13dvv0 jo5 shows the force versus the object's position. Find the work done when the object moves from 0 tve1+6x 0u3 x)j5mlorj6bv xv3puik d7o 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 ofjbti9( i;n ra:s3 nm /t1)lqri the force. The graph in Fig. 6-1 shows the force versus the/iil r tqtn) s;nmai9:r1 j3(b 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 diu, s, j6xmy g/(l+bm7 e3xepwkrection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object m(xs /3bwg7mmk6elyjup ,, e+x oves 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 direcy)3b- g x)m nja;bh)zph6x; mrtion of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when ta)xnb mp j3h6; m)h -)zxr;bgyhe 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 )b3 f :(.udpqa/kki;sqpva mh dti3 1dg3d7i,is applied to move a 55-kg cart (initially at rest) acrosdd 3kqth.v 3qmd3(d1igi/7: pfa ),; ibspauks a 10 m level surface. What is the final kinetic energy of the cart?

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

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

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

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

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 Na3lhp uulw r2(u5mgz t6s3+r4 is applied to move a 55-kg cart (initially at rest) across a(mup 2z lr36h3u4lgtsw r+5ua 10 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 ; lqml z8;a6sgmx9mhqw egb+5a.+ bf 8of 5.0 m/s. How much work is required to stop the mam86a m9z8;xw mqe.+fl lh;+saqbg5g bss?

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 initiic,wklen uo 4c,+k1*d s.1d z-n i(iz vr6kk.hally moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same ci,v1 n.-isc k(d hne*z6k z1,r dol4k+ icu.kwondition?

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 isj nodm+.c n 4:tc +m+r;xu3tii cocked by exerting a force of 20 N over a dinc: .+xir+o icmj dt3tn4;u+mstance 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 vertic. g0(ai*z4k5z.ujk hxst u( b dfee+)tal component of 60 N. The force is applied to a box which rests on a level frictionless flooe+zu(t() xe*5g u.zfs 4a0j hi kkb.dtr. 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 5il6qx-ba xi /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 stopping force actiilq-x6a / xb5ing 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 he 9kh 9n7)rhrno9/mojnz j7zkm;, s(ykight of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational potential 9)on, ky skhk r7z7 ;jm9on/9mzh jr(nenergy?

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 l6sb)km- ;dx/so)xb*4 qts epuong and rises 2.0 m. If the plane is frictionless, how much work was bt*k;x )b u/ssx)d- ps64qeom 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. What is 0w+cz.dss *,jzoh4 y athe spring conszw4yd jco.0h s a*s+,ztant?

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 constl)5*)hubm c:n sua 1ocant of 60 N/m. How much potential energy does it sta:s)u5 hb1 *cmu ol)ncore, when stretched by 1.0 cm?

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompres uw.kfsq)/ws) 1f 7qwxsed spring with a spring constant of 25 N/m by ff)sxq)kuq ws7w w .1/10 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 o tzkmcik v7p-9wdlz(z07d,v ) f spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x = 0.( 0tzidzw, d)7czkl-p7v9 vmk)

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 comp qi:8t2 f1bb dcj,f,8cuen y6gressed by 3.0 cm. How m ffg q2: 8dcn8etji16,b yucb,uch 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 4vw xcv8 ury:9 c0ai9a50-m high slope. What is the speed of the slier on reaching the bottom of the slope? (Negva xa9: i8c4yuc 09wrvlect 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 initiap z(4mhu7.tsn 1rkv8zl speed of 4.0 m/s. Neglecting friction, how f71t4 . kps mn(vhur8zzast 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 incleyj+ /x, hk-mrined plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical heigh/ mk-+y,er xjht 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 9kjq:sa nv)9q)3bzk nm above the floor, its potentia)kb k39s) a9vnqzqn:jl energy 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 from ground b0vojtbll9c 2,f:2qsch,v nx*i-* xglevel with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical hei*j2vl bxnci9,f -o,b:q h *xgtc02lvsght 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 ij--ti 5if2ttthe ground with a kinetic energy of 220 J. At the highest point in i52itjit --f tits trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at i5h)ff ou ;s8ka point 45 m above the bottom of a dip (See Fig. 6-2). N;f5fh o)uksi 8eglect 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 b9;yicm4,2aiag ij .fupk 78lspeed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2)m7ig afb8u;p92yk i i,al j4.c. Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a di:jo ok +/ m9zv vp*xzbdnlz..(p with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of th+ l(zn dzojmvzk:vp* .bx9.o/e 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 balycr 7 pgduq3 ,mf1n06sl 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 pulled 30 cm away from the vertical axis and rele w phvjj(-,ik4+jyqz4ased from rest. What will be its speed at the bottom v4yq-h+j jk,(pi 4jzwof 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 horizontal spring 9 sj;a/:c cnrxwith springcj:sxa 9;rc/ n 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 stope87nzyka8c tqv *x p0+ for a red light. What work is dt*0 8eyqk 8xazn+p7 vcone 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 a horizontal surfa*hyflv:se2 u*7fbc6p ce 3p)zce is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance wilu 32*cyp*h :b z )e7f6lcspfevl 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 has 24 J of kinetic enoerzui v7x21u, ; )ebnergy. The friction force on it is a constant 0.50 N. How far we;,27ou) vz1iurnxeb ill it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a level surfa(ekf.z* o, g(,t ee h*rcs6jrfce. The coefficient of kinetic friction between the mass and the suf r*o,h,(.(e jse tr*z e6kcgfrface is 0.20. If the mass is moved a distance of 10 m, what is the change in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest fromhov6 t3 r8 ola /v4q83dqaqij/ the top of a 50-m high slope. If the work done 388/dvq qviajq /3aoh4o tlr6by 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 4.0 m long and rises cp 9nosdc)4(6 gqh7ry2.0 m. It requires 3200 J of work dsccro9 4)hg(6q7yp nto get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of a pffglqw (7.g.(dcsfzc,. vr j*lane inclined at 20e above horizontalcwjd f *g rf(,z..(q7fcs.vgl . 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?

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 mz-jtg+ fyr nbfl1 5f9 2tc4:oxjrp 5ljx4l 7(x, and strikes the ground with a velocity of 7.00 m/s. What average force of air fl (2j r5pn1xj b lffgtyfox-5x4 9tj+z :c7rl4riction 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 fligg,kru:shzx 5l ,bk)1x ht of stairs 10.0-m hi1x:kgb,u ,r hkzl) xs5gh, 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 q 0fsr,.sf f9m*k5tc eto move an object with a constant velocity of 5.0 m/s. What power must be delivered to the object by thefqcmrs0f, .tk5*s 9ef 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 m5;jbep9 j:l-r3y pofaotor that runs for 1.0 hr? (1 hp = 3rlpya j 5f-;epoj:b 9746 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 ed w 1.fw.hjz// 2ahvbt -a9id500 W while riding. How much force does her foot push with when s/b. d. vi fdezh9t wa2h1-waj/he 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 eglp p(xwf-4e4alon 8 -:id. ns. What is the average power delivered by the engine? (1 hp = 7f4ei-: 4xel od(-lgn n pa8wp.46 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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