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

1#

What is the correct unit of work expressed i8d g,f784tsi a vmo,/ si( j*vuaw:zqin SI units?

A. $kg m/s^2$

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

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

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

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if therefc qd yc4.8 -(nwp:og s7dmxo3 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 harx5wouw 4:j jxq2x0x9 ad against a stationary brick wall, the amount of work yo5x:w xujjx2 9w0 axqo4u do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is being held there. 8mndaoba o0z8mh6i y; i9 +ve7How much work is being done inoai +b6am88v0ho nm y9i;ed 7z 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 forwjr82adhr3f6r0n:aktvrct4 5y lm tnq* in85 , ard at a constant velocity carrying a 10-N object, the amount of w 84:,3iytm8j5nkqt2 lr5 dfa0nchr*v rnta6rork you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned to its original pe 9:;lg0bhyk lmcr,6aqvg; 4fosition. If the total weight is 30 N, how much work was done?lgchqgve ,4k; 0;bmr 9:yfl 6a

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 actiph fyduel7k.tm3, ;6w ng on an 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 of 6z)*taz yfft/ p2e2isthe work done by gravity while the ball goes up with the sign of the work done by gravity w2y a p)fiz/tst62zef*hile 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 posisg6jdr x t /5ztvij.3;tion (F vs. x) graph, represents 5.j6tt/;dg3rzxj siv

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x), what represents the worghua s-om aws*3moc2m5 +o) x,k done by the force Fgo) wcum xo*o s3sa5+m, -a2mh?

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,sr(g, nhjcmd- ai :u, an 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 ob./; doaxkdt,3tdpj, txvch ( 5ject 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 on an object is zero, then the object's kinetic energyohe8 o7gzc6 lwc3snh3 u 30ynw(e,zx+

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 ca2u g*c j6vgu)aat+p f)r, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that o*fupc+jua26 )a)vg t gf 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 ofan1d pg 0kh((yi m0da( car K. The kinetic energy of car J, compar0aap10 ygnd(i m ((hdked to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its orig761j;(oefmtm zc+vzc) 0vrd4 qq+ hvfinal speed. What is the ratio of the final qm4d1o )zhcv v z6fe+qmvt7r;fc 0 j(+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 movind woia()zua)l /85 kneg at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of )o zanu(k)di5 ae/l8wthe 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 qs.30xo v (iz+v yny8ehb bi.7with speed 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 tyv n(..vs07oxi bhei 3 by+zq8o 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 2kbe21w 6ad2ti6dr.qp kt*ck your car in a panic, and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skiddek6.w2dd br1kaptk*ce2qti 26d, 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 o bk: p rbxiicks ct :/vld2+2:(yvp)i-rbit. Neglecting any friction effects, what happens to the planc-ts v(bxp:kv l)ik rii/:2byc:2 +pdet'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 p8zy2pir m21kqb /g lz5rinciple.

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 h p/4tt9kv0b mxave negative potential energy?

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

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

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

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

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above the grou3m9zi- +sbdxr *mj3ycx)1mxi nd. A second object with four times the mass ox3xymi*ji+z93m d )sxbmc 1r-f the first if released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attac:mj;v; vs 3vrkmh6zxp*q;q5 nhed to the end of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass i;;x vjqmvz 35;*hmqs6 kpv:rns added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energy of a s ol muk+h,(ct+ystem

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 itezw f: ao5p0y(s potential energy e:5zp(y0aowfU.

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 ofuqb3ko i f xt+2fb253p( skv1f 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 heavechi9yyejj8 9zt2fa d (5r*)s y object are sliding with equal speeds along a level frictionless surface. They both slidei h5e9cja2(y fyz*)s9de 8trj 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 m9+p1 9rcw qrx*x ey))z2khn s$m_{1}$ 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 mechanicaljn /8n2;mn bde energy for conservative forcesne m;nb2 8dn/j.

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top of a building, through the air (air friction nmsp b m25uh+23zq*ihis present), to the groih+zb 5s2p h2mmqn3u *und 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 not ( c4p4be4.k+a lg*0lr vxrbcwignore air resistance. How much gravitational potential energy did the ball lcle *. 0+b bcgx vap4rk4r(4wlose?

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 losesl4dka.jwn 7oqlxa8t(l ) 9hx0 30 J of gravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball go tkl x8wld(.a )na4h97l xqj0ain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation of ener,q84wqq8jtjqx;h xk 3gy.

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 isicps7cp pz1 r 25nib04t4+nkf

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 expripaxz40f-l v88n -luw essed 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 unit of powevxf*)a g3rg6jr?

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 3l7 3pnkzx)gn; la 9jy9 times the work in one-third the time. To do so, your power output must ly;n9xp9 l7nz3gak)j 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 accelerab,wj4jk tr tyv/hkf :q69-o6vtion, 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 wighh85a n) sk xv66lzx5 b1:xreighs 90 N, how much work whlvk xi:n xs 56x1h5rz8b)ga6as 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 1.0h;+eyc.1ojk 4u8f m vl m, at a constant velocity of 0.50 m/s. What is t+.yl14m;vc koejh8fu he work done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N(l3,a dwho8n l9qsj(r0vb m (o for a distance of 50.0 m. What is the work done by the 5500 N foq 09ooml3j( bhlw8 ((s,dranvrce?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force f2y;2xjv x 9ecof 5500 N for a distance of 50.0 m. What is the work done by the weight of the ele9xxy2je2; fvcvator?

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 of 3 l+6-amq:.jtpjirh* lx y5 uz2jeqb7 5500 N for a distance oqj53ye7 *lraumxlz j6:.jhi2tb+ q -pf 50.0 m. What is the net work done on the elevator?

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

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

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

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

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 m up along 4yux6upt:ll ax 5cda ,i o,s26a $37^{\circ}$ 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 dbi7n sq7 db8y8+c 5jaiown 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 Sln s o3lz sf tpxu5y2+l58hs77arah in a sled on an icy surface (assume no friction),25l sphn5 x 7sz38olutysfl+7 with a force 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 direction of the force. The graph in3k,y kji s;id0s*lap2 1emb s+ Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 0 to b*kli sima0 jy pek,1;ds+32s2.0 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. The graph in Fig. 6-1 s+knpfdj9 b.t gr52lf x9s82zuhows the force versus the object's position. Find t2b9ffz92dst r5lg. ku 8j+pxnhe 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 thewdb;x3h16 gye force. The graph in Fig. 6-1 shows the force ve;be6h1xyd3 g wrsus the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. d2j u:+( ogn6dsiaou4 The graph in Fig. 6-1 shows the force versus the object's position. Find the woru6:u oa+4dg n(2 doijsk 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-e p*s 6huc;wp:y0g gb-id wc4 N is applied to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final kinetic d4pw y b*uw-c: ;gg0pse c-h6ienergy 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 tm1:, pz 1 *cpuka5hcaoo move a 55-kg cart (initially at rest) across a 10 m level surf 1kco:aph5 zc u*p,1amace. 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 speedsy/kzml0w h kz)u.:0x of 5.0 m/s. How much work is required to stop the mass0m) .xkhulz0w/sk: yz?

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 v imhwnl3(h3w5lahu/2i2 2q t5 t9tjvm/s, what distance is required to smln2wq(3 h/3t vt9aitlvhh2i2 jwu55 top 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 propels a 10-g dart. b20d:u+icj 28 bfqv/8e x ch*osuhu+yIt is cocked by exerting a force of 20 N over a distance xe:i+vcbybo8hfu2* /8cuhqsu 0+j2dof 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 6+; xxhtmgv hz)a*ecuekk 1c32 -rm;uvertical 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 horizontally along the floor. What isc xk uxrua3+ ke;e6t;mv -mgh z1h2c*) the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of o60pq wn:ox3e hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm npq30: we oox6before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height ofml75 nnm-8m2+lm6 wf ttbdij bvi-01q 7.00 m above a floor to a height of 13.0 m above the floor.w0bni j2f 16v+mt8lm 5nmqlt- mdbi-7 What is the change in gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plane. The j8bv7lf2v )zfz5dr v,plane is 4.0 m long and rises 2.0 m. If d vfz ,brv85v2f)7zj lthe 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 spriv5 8*nyhh* vqhng to stretch 2.0 cm. What is the spring constant?nhvhvq y**5 h8

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 awua u02hf-sj- spring constant of 60 N/m. How much potential energy do2u aujw-hf -0ses it store, when stretched by 1.0 cm?

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

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an ikx -dnhaybz.k2fuim .98w2p ;nitially uncompressed spring with a spring constantbf d;-2h i pk.x9mn.zuyak2 8w of 25 N/m by 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring o4 miqo)qk-dly7iirks v6iq-rs657 f :f spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the unstretched position is at x = 0.: q6m7iyvisf kslr doriq6-qk-)745i)

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 compressecc zto8h2s 2rbi 4a+b-d by 3.0 cm. How much work is required to compress trc+ocas t z-4228bi hbhe 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 slope. n7tj1+ :zklkp biu7c9What is the speed of the slier on reaching the bottom of the slope? (Neglect frictikpb 7i c+l7nz1uj k9t:on.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top of a hill with an initial spa4j2 uxmn v.6b:m8uvk eed of 4.0 m/s. Neglect8bavxv.2nm ku6um:4 jing friction, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a fri s8a8odpl aafa.:6r/h/jdf5h ctionless inclined plane. At the bottom, it has a speed of 9.80 m/s. What is the vertical h.das8/: p 6aarhl8f5j odah/ feight 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 te aby4r d;up; gtq7kr5 (-dj.to the floor. When it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy. How .;qa7e-;5 t pby rdu4jtk r(gdfast 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 wi)dhf +9 l ,h0y-jxagcbth a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise)x0yag-d+ , h9clb hjf?

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 kinetictoe 9j-wita c.e,o/ 3ekx3 zp1 energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, re,teiwek1pa oz. /9jc3t- o3xelative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at a point 45 m above opk1 ;qhzxd-1 x(r*skks ;c8bthe bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of kq* d p ks;;xx-(1zbso rc81khthe dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m above x4tf :cd9.t88bbybdqbhmgzg(0*q c17 ; japs the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of pt 4;cjq.gbd 8yg*8b9 0hf(a1z xmb s b:tqcd7the 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 ofdu++ 3sp9. 1jy8ixc-2yhr e bi5jpn wc a dip with a speed of 2 1in h3+cpd8+.y9j 2cyxw5sre uij b-p5 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the balllaj y2 o/1.brb 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 thp3racb5.p6 ,4eqw wj ue vertical axis and released from rea jr5wb3ep.6w cu,q4p st. What will be its speed at the bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially uncompressed h9p l*0dgcn0o5wd. sptorizontal spring with sl. c gw90* ns50tddppopring 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 stop fo 18rbhuwt0 5 xx q(y*4m jw,ded,zgws,r a red light. What w*ur ,4w(8qehgmxd t1d ,z ,xysb0w5jw ork is done by the friction force against the wheels?

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

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

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

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

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg objec j qg8z*kzkm,5t and a horizontal surface is 50.0 N. If the initial speed of the object kzz5mjk ,8*q gis 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J of kin n 8m-g4h a9ajgylkz43etic energy. The friction force on it is a constant 0.50 3l ahj8n -ag4gy k49mzN. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontally to a 2.0-kg mass on a l,92kb i)v0bj 9ts jspdevel surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is thibjt92p)9d0 vbs k, sje 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 higdjwkp a/h )d1-h slope. If the work done by fric)h p j/dd1-akwtion 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 g15au/ r7w j*sai e:jm,ev.buup an inclined plane. The plane is 4.0 m long and rises 2.0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on th ib.gs*:ua w,mrj /jueev15a7e 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.ct9b+m ahf4 b above horizontal. The coefficient of kinetic friction between t fm+bhc.4a9bthe 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 m, and strikes the gro7.hug kbj1vwl/ 1o5ko und with a velocity of 7.00 m/s. What average fow/ok5jo7bgk1u 1 v.lhrce of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runsia,t x+o cyt62 up a flight of stairs 10.0-m high, i6t,c tiy+2xo an
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 ob-ks3zvte *yg vq*v .yusim +43ject with a constant velocity of 5.0 m/s. What power must be delivered to the object by thees.ymkyzv3gvsu4 it v*q*3-+ force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used by a 1.0 hp motor that runs for 1.0 hr+,s;ho4 szivrkmjbxfg1 n/;5 ? (1 hp hsk4 r,;g sin;zv/1mbj5of x+ = 746 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 fvhv+sd3 gucotj f++g 83:wl0much force does her foot push with when uv0ls wf 33o:tcjd 8v fggh+++she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates from 0 to 25 m/s in 79x;6sh/kry c:p: tjyn.0 s. What is the average power d;/x: 9t psnkyrcj:yh6elivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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