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

1#

What is the correct unit of worksrs7b* v;g bh9a s1zk0ljl*:k 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 a s en2s732clcez g nt4j.8x/ dbyoh.h 9qystem 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 against a stationary w,1ja: xwjz p;doo .(lbrick wall, the amount of work you do(w ,lopwx a:ojdz1j; .

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 verticfb1ifc9 ;7 dzyally and is being held there. How much work is being done in 7fb;91yi zdcf 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 aixq7k1 ( ykk il z75-yoz7ga0b constant velocity carrying a 10-N object, the amount of wxylk (y agk0ikboq75i7 z-1z7ork 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 3b; w.tn7uno5l1p afy9.0 m then returned to its original position. w5n91f7o bptan;luy. If the total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force acting on an object do wor*alep o- 4ofw-1psw)ok 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 str )d1bl4yj0 humzx51p aaight up. Compare the sign of the work done by gravity while the ball goes up with the sign lajp1bm41yu hz)5x d0of 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 b6wyr bdi sr 0d2(). 7fhu.-jl czn9lwversus position (F vs. x) graph, represents-wc09bfw ujsl dyni2 b.hlz(d. 6)7 rr

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 positioz 03j5elc9f spr/o(l fn (F vs. x), what represents the work done by the o l/fc5jel3rspf9 z0( 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 tne 3glm,/ud28kv x)d v)ijc8whe 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 ijyvq m00 10dccs 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 on an object is zero, then the object'zx(aw f:;vfx3g2ixs0s kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is moving at ;fl4c+v2 ok+q +krgxvlu lt(:twice the speed of the car. Which statement is true about the truck's kinetic engq l vt+uvkxfl+ 4:(lr2 o;ck+ergy 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 h0lww3f1 lxobl-bs52q. k jb 23vf dc.palf the mass of car K. The kinetic energy of car J, compared to car K k3f52j fwl2blo.d -wb. csb1p xq lv30is

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 bop:k-m)fat * ,o9nvnamz;h- q ip6( vhwunces back with half of its original speed. What is the ratio of the fina:*q(a-6 9nmh kzv)tv a hn-iopf, ;pmwl 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 so9shgk+ l3pdcg 9gb /y.nxet- z r516wpeed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio o1k-rgghc+o/xeg93pl.zn65sdw b y 9t f the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-*+umawk u/t88-i qyz vkg mass is moving with speed 4.0 m/s. Both objects encounter the sam8ziq a uy8+m/wv*-ukte constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a certain distance on gc5iu opq l8 w6i.xl)(;w9y ada straight, level road. If you had been traveling twice as fast, what distance would the car have s9 iq)plwl5c8y6g(;wixo uad . kidded, 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 a4l5u7jgsc n 2 w5vfsc4n elliptical orbit. Neglecting any w2gcun 5vjfcs 5447l sfriction effects, what happens to the planet's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principlew ( n,-lw1ujbigrig3)ib) 0u:0i p jfd.

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 negativisv8s u- )ee+ve potential energy?

A. Yes, as long as the total energy is positive.

B. Yes, since the choice of the zero of potential energy is arbitrary.

C. No, because the kinetic energy of a system must equal its potential energy.

D. No, because this would have no physical meaning.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released froe t.nzlax- p,/p /p3fem rest a height h above the ground. A second object with four times the mass of the first if released from the same height. The p,lzp- tn./3x p eepfa/otential 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 springop g5 (-dqyv-k causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential energy of the spring 5dvk(o yq-pg- 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 a2ys8tfcfht tz9+p 8 6ma a)fa2 system

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

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

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kinetic energy K, to its p/k 6rtbf( ve:h16maql ser:e+otential energysr (a6m+teh6 :ekfe1qrb:lv/ 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 gh2z3qtik -z 8c.fhf7w0xo x *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 obj 6psdw e()u ohn) u,22tu/pbeqect are sliding with equal speeds along a level frictionless surface. They both slide up theepe2du,(2/tqows h pubn 6))u 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 +sb oidz:3amb s53 ja0,ombv7 $m_{1}$ 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 for conservxr /ti 75b *1fuay/v.opiq6ed ative forces.i v /r* 7yia1fuoe5 d6xt/pq.b

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 buildi4szf6. bb1itp dcr hl uw)34m5arj(1 rng, through the air (air friction is present), to the gro1urami .56w3t lfc (bp)s4drhzjrb41und below. How does the kinetic energy (K) just before striking the ground compare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Do no3yb7nyul/)q dq16y x qt ignore air resistance. How much gravitational potential energy did the ball3x67y/yny1qud qq lb) 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 ofcg g/*2nh3x jh8e i1hs gravitational potential energy. Do not ignore air re* h 2jn 3hexih81g/gscsistance. 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 cons,ztoe5jrd :n 0ervation 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 isi o/:yoqwx4vb*u5; hy6 n fe,n

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 ul)h nmi a*y7 cnbm,zj*)uq /s4nit 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 xysu x7u /4xr4t,w0ab :mkd- eis not a unit of power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the work in ou oz0*k m:wz)xe1*m ljne-third the time. To do so, your powzme wk* ) *xum01lz:joer output must have been

A. the same as yesterday's power output.

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

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a coip c(:bj)8 j: twf0vvvc,pkp3nstant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If the object w y d:yyzxmyk9 nu,b*8e20sq mc5-sth- eighs 90 N, how mmqt8*nmey, s-b0x2c:u dyz5 9-yh yskuch 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);04rym 6pwn knt5y dd 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 rdn5kpymw t640;dyn) 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 with a constant force of 5500 N for a distan/z skpps :*m;ice of 50.0 m. What is the work done by the 5500 N fors /;zi:ps*mpk ce?

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 /zk4h u2dxx4gz uqq9e/ v6;kg with a constant force of 5500 N for a distance of 50.0 m. What is the work done by the weight of the evx /k;xg6 h2u9 gukq/q4dzz4elevator?

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 :8mr6rb7 gsu kof 5500 N for a distance of 50.0 m. Wha8ur 76bk:mrsgt is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up al 3, (lc 1gmsy.,euiwedong 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*.+fr :cqk ygxo8w zs2 8.0 m down 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 lit;a vl)qa8-n sd ;aoacfae0v:0tle sister Sarah in a sled on an icy surface (assume no friction), with a foe aaf8as0vdc )qan 0l -:oa;v;rce of 60.0 N at an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the deeu 1t-lkw0f 0esu-/iirection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to 2.0 1ekw0ie su--/ef l0u tm.

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 diyh-6lz1f:gtrnu8.7o cib, barection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find tf7zh:uy-6trn bo.bg , l cai81he 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 Fig. 6-1 i1t8khucuq2g v w wkemdz;k(2(p : 0;jshows the force versus the object's position. Find the worzm w2ku0c8ujh(1 k( e :gdqwtp;2v;k ik 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 directioi8pewe 5 q7er;n of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find thqe8ri 5pw 7ee;e 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 (inmfn+vlq 5; qn gzh(++j0rx m5fitially at rest) across a 10+v z+g0j;qnh mmxnr5q( f+ l5f 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 N is applied to move a 55-k2mj8tdvary- -g cart (initially at rest) across a 10 m level surface. What is the final speed of8t 2-- rjmaydv 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. Horb+v 9y5ko04 ,b rxgsmw much work is required to stop thekrm0vbs +r,45xyb 9og mass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initially moving at 25 m/s, what dis)h m:3 lk5zl6phc v6hstance is required to stop a carh)5l pk sh3vz6 hml6c: 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 propels a 10-g dart. 0yy k )z 9*byegvm 2gbn2bt52dIt is cocked by exerting a force of 20 N over a distance )5ggtb2ven mbyd*y y9 zk22b0 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 hofhpkw0e xq(g-n2djrg-;56q j rizontal component of 80 N and a vertical component of 60 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 kwq--xjd;6ggn2eq h 0p(5rfjhorizontally 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 horizont8xb-5vcsgv.5dhs ze1ally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before s-5svv8 gbch5xed 1.sztopping. 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 afm* dxf5dk o0n .x3tt/ height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change5x t30* ffnddkm./txo in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The plane is 4.0 m lotj 8szlj73xp1ng and rises 2.0jpx7lt 8jz1 3s m. If 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 ontt8aemz2m/gq tw+vrh u8sw14 *; w;oxbo a spring, causes the spring to stretch 2.0 cm. What is the sprin;+u4zr1qt*vw h8 eb8t a/ x;o ms2gwmwg 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 constan ovgd,jw;sl-,68rarb mj rk+ -t of 60 N/m. How much potential energy does i;grrkd so-w6v, ,b+al jj-8rmt store, when stretched by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompressed spring with 8b k :zmx2s fr;a7a5eda spring constant of 25 N/5xa7fea8rks 2m:bdz ;m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N/m frod0 9pcfrev3:lz - 5am. 6e+qjmo ebmq5m x = 0.20 m to 0.25 m? (Assume the unstretc ba m.dfq v6e+pm rej55mc:-ze q09l3ohed 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/9fonovrwpv0xl :2o8j2 a /sb7m is initially compressed by 3.0 cm. How much work is2vvb ooj9 :p0x72 8a swfl/rno 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 sp hjblg;57 :mbov5e 8llope. What is the speed of the skier on reaching the bottom of the slope? (neglelg b57p;5jbeh8lovm: ct 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, pushes off the top .3v5 2 f/5gddqcmorz wof a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m in elevatcd.of23qg 5w z/5vrmd ion?

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 fwplcob0 hb +gu(0q .5grictionless inclined plane. At the bottom, it has a speed of 9.80 m/sl.gbhq w05 0g(ob +cpu. 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 floo/p) s1on;bgn af3 mvq*r. When it is 0.70 m above the floor, its potentialno/* ;qf spmg1)nvab3 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 q;ihn mncs9p9 sj:(;d straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical enerpq ;i(snmc9s: 9jd;nh gy 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 a kinetic ener4.(8 khdlr czcgy of 220 J. At the highest point in its trajectory, its kineticdl 8k(4.rhz cc 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 start,hf0 y.r1gjg as from rest 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 th0f ga1y. grj,op 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 sta * v,yv3b2ypwnrts 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 ,ny2v pw3yvb* 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 6y)i ix/f k43ykvhhb(above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be t/bkhk )3yhi4xi y6fv (he speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the ball at the bottom of its swing (pow)u +2frnwj: dint

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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 0.13 m awa riup3 w nx 4nj0jee1uv-0sj .1xw0i(ly from the vertical axis and released from rest. What will be its speed at the b0(x- ve 4jxpn1snu1jr.l0 0uwi3iej wottom of its swing?

A. 0.1742 m/s

B. 0.464 m/s

C. 0.697 m/s

D. 0.581 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 iniy s0 zx 1-2: +f-sgkst/qamnr.or+duitially uncompressed horizontal spring with spring constantnzm2ukxr +st +f0d a/-os1risy:q-. g 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 i3)vjf n)ocvk 48t z4ps*t5p8r ymrg02000 kg car to stop for a red light. What work is done by the friction f4 *) 8nv p40zm5sfvt3 ipjrry gc)to8korce 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 betwe00nc1o)(b uxmp d tj(k/tc bma4yw7 9men a 60.0-kg object and a horizontal surface is 50.0 N. If the initial s4dc9oupb)m 0t / yjx( b(manm7 t10wkcpeed 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 bz/y1+l+vc;3f1drdwtx k* rz a rough, level surface. It has 24 J of kinetic energy. The friction force on it is a constant 0.50 N. Hod kz3rw+bx*clrzt1;vd yf+1 /w 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 level surface. Thjb9p: fu0 sr/kekxq+ 1e coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is :/e qjrfkp0sbk +9x1umoved 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 top of a 50-m high slope. If t3)ax ix*vjfqsj ;:o:rhe work done by jx:jfi*sq;) : av3xo rfriction 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. Th 7 ;kj dt:4); 4rxkg,hpoekxvge plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get thk7 kjp, ;r4hg xok4txv;ed)g:e 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 plane inclined at 20e ttie;+l.*w eo above horizontal. The coefficient of kinetic friction between the mass and the .wlt +ieeto; *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 f0:x sz .5apamur3u0y brom a height of 10.0 m, and strikes the ground with a vely50am x03z uus :.pbraocity of 7.00 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 u 8xfsc i7.xz4tsing energy when he runs up a flight of stairs 10.0-m 7zxtsxfci8. 4 high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velocirxs3k uqn) 2qb4d+ c0kx,w,zwty of 5.0 m/s. What power must bewxq x un3)wz04bkd, ,r+q2skc delivered 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 qsaschexl5-/zelz 47k4dk x-: 0* ertby a 1.0 hp motor that runs for 1.0 hr? (1 hp = 746q-dl t: x ez4e7/4 5lkskrez a0hx-cs* W)

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W while riding. How much fow.q, is)5yom : 1fjkkwrce does her foot push with when she is traveling at 8.0 m/ssi:)yk ,f1omwwk q5j. ?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s. What is the averageolu0hf(djm:dr j(y 0+ 5ee/ax)t zph7 power delivered by the engine? (1 hp = 746 W)u)lr / (j0jtfzhh oxea7:d5m 0e( +dpy

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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