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

1#

What is the correct unit of work expressed in SI ptvn5q3ue talb :)(b i-r1jg)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 thrm mb m14p-0cgere 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 asq5+ ,xa9 p/vo7rvf bqi hard against a stationary brick wall, the amount of work you dv/q+5 v pb9f,qi ox7aro

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 kg(zty42spln;u l:h9 ej e :9jec i:a)much work is being done in holding the box in this positioijt:)ye99:(ng 4lu e j alchzep:2;k sn?

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 constantx,d3+c: x vvrb velocity carrying a 10-N object, the amount of work yo v+xd3:xc,b vru 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 ori/m vq2mh+q ;kzginal position. If t+ qmmqv /;2zkhhe 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 obc o7atw4ne gt3 d;w))sject 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 straigj;:k jvfwrw kte .521 5ir zodt16o f59usv(hnht up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes dow9;snfjt5o5w2 fdvr:uz vj6oe kt5rkw1 .1(ih n.

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 cyo*;yb*:sph0zt m(wvg u+r1 wurve, on a Force versus position (F vs. x) graph, representsw ry:byo10ht*zgmvspu; *+w (

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), whatxc n85*z)drp0log/rnt;c0e x represents the work done by the forcepnz*rnl5 t re0c/ od;cg80 )xx 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 oeypfg-1b vv7zm7xx+ 6 )3rctj bject 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 object is negative, then the object's kinetic enersk2qfol9;2 y )j.*p 3,tq raklbbx 9jxgy

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 ene78n/uk 7 kzc77ks* nurgv3vhjrgy

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 muc /o/v af qyq1dic3fn),.mig)m h as a car, and is moving at twice the speed of the car. Which statement is true aboutgid m/oa 1ci3f)fy v)q./qn,m the truck's kinetic energy compared to that of the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has h,rkx+.cuhiz. alf the mass of car K. The kiuk +cr.z.xh ,inetic energy of car J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original speedwiiwz+gcjs4vln)kd6 7p3 z3 /. What islz6 sjwcz/iidv)+p73 gw 34nk the ratio of the final kinetic energy to the initial kinetic energy?

A. \frac{1}{2} \;

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed o :0v8+mbhjhp41monbe)h) z nrf 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to8emn0hj op4hrbm + b)zh1nv :) 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 1 v v +va1 .rtn d1wpoovm520gn4rtca*with speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the1o.a 0+4nmtd11r pw oca2vrv5g*t vnv same 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 isbee hfe6i.vyh+3 zq p.w:6g3 kcjz* 6n 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 skidde.3:ez.vi6 hbp+j k e qyh cgf*e3w66szd, 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 tqei5y/vd p+ lew ,*+ryhe Sun in an elliptical orbit. Neglecting any friction effects, what happens to t* +,erp y/ile+dywqv5 he 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 ua7 j04bld rm 1l-6g*duggzp* l1te9qu,mh4oprinciple.

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 negjx 3 /zau9ccj)ative 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 ground. Aar ws;ya/cmj w 8zv5ydu6c(5,a3) x sy second object with four times the mass of the first i/yyacwwm8;xur ,ya)ad3zvj5 s6 sc5( f released from the same height. The potential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes u. lu x(vsq4) 1ec/hctit to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, the potential 4ch)l/cqex1u (vtus . 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 sy(tlrm tc324hzeoz;z67jr: u istem

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 kineticykf*a*.zh r6 c energy K, to its potential ener 6h*zkycrf a.*gy U.

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car dr0;18ecy+hx q1vf0k p h2u3sptzqmz 9tiving 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 ar uv(c560 r)ij5tbw;d6aw j(t op g/vs very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the(c)5rstowvbaj6dipt w6rv g0 5 /ju;( 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 oyro;q6iifh: xyrbq )+*6t(e $m_{1}$ 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 ozber84:.ws6flb zj+g5q b e:t f mechanical energy for conservative forcesj8ef.t4q w6 :5bs eb+ zgrbl:z.

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, thrr0.mtv/ k 35o yewjul2ough the air (air friction is present), to the ground below. How does the kinetic energy (K) just before stri 3wtur j2ey0vklm.o5/ king 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 not3up/j( i4,nt ng s:esv ignore air resistance. How much gravitational potential esp v4nstun(ij / g,:e3nergy 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 30 J of g9 uegdbc;.hfx( .0wo tg-b;v rravitational potential energy. Do not ignore air resistance. How much kinetic energy did the ball gafv o w9 t0;;cd..hbgb-r(e xugin?

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 e9/*n09(i(iwt faa rtith6p uof 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 is4crpvb 0putnm 0ijq.f. 1k3. o

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 kr ;73*7l ds(y ecggl vtjpb0,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 unib3o(* ; xrpviken7-a ft 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, opmh 3;7po-5culcl:yosy9 h7 y8a)dk you did 3 times the work in one-third the time. To do so, your power output must have:79)hylm odys calp 7op;- c8u ky3o5h 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 constan ebk v+k); 66+evbwt:5mjyjhi t 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 weighs 90 y w:tc45:, d wbaut: vk65egi0 9njxlqN, how much work was done in liftinu ka 0:ebw9:,vqnxyd 556 l :gwjtcit4g 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 boow5qcr -(bzv86r yvb1h k up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work done vz-rb 5byc6(qwh 8rv 1by 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 ftw5 x:mm /i03ticn.j0er ex:for a distance of 50.0 m. What tn:x0 .5f:r3w mxcj i/me t0eiis the work done by the 5500 N force?

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

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

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

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

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled*/llhxvqsko6 7br/l uy -2tprrc 4(t1 upward with a constant force of 5500 N for a distance oftlb741r*u-hx k p srr(cl2 /oq6t/yvl 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 fouz g*s6:-kj8l7pbxt lrce of 5500 N for a distance of 50.0 m. What is the net work done on the ele78jg k*x6zu plltsb :-vator?

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 muf5+f/5bqirnhr2 1 d 6.0 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. 3iq6 kto+ -, vcl0(a9a y;zo jtb5odnn5gtq,b0 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 little sistey*0la n omrg48t;gl3 nr Sarah in a sled on an icy surface (assume no friction), witng 3otl;g*80am rn4 lyh 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. Thbop7rb-ivl4a oz eb /31x*9 whe graph in Fig. 6-1 shows the force z pe-3b1wv97o b/iah *l 4orxbversus the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the;dyt isok2zji,h *j,+/, yjxu force. The graph in Fig. 6-1 shows the force versus the oj;stzy,2 x/oki+* jdhjy, i ,ubject's position. Find the work done when the object moves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the forr:.)k ua1jg92bn fks--xcjz8 ims-jpce. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 4.0 to.)kngr-b8sm cp usij kj2-zjf-xa19: 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 forcewh e 5qib,,/lj. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when t eiw, h5j,/blqhe 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 caj0 k;ia2x ifzfy (uo;: .tztz;rt (initially at rest) across a 10 m level surface. What is the02 ;xtt .fjk(zyiua:zz ;o if; 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 bk0r46+m 6r.uefym0u1qwra emove a 55-kg cart (initially at rest) across a 10 m level surface. What is the final speed of thw4 mb66raq00 1 ky.mrefue +rue 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 u77*iw.bz00dclioe u of 5.0 m/s. How much work is required to stop the masiiwzo 7uub ed0.0* lc7s?

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 initiag7+sq lir,9. mra5 skbt-s 4 5iu0qzxmlly moving at 25 m/s, what distance is required to stop a car moving atl05itx54+qs-bki.szsumr 9 a7 ,q gr m 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 proqlpysqkkb;+8s,r(ht/bc v4nq vk5x ecy/ 8*/pels a 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed wil k4;h kt /sv5k8sqrbylcpn qyq/bc+e/,(v * 8xl 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 horizonteak o88qp h.8 lx/qok7al 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 horizontally along the floor. Wqk.8ao88 hkelop7 /qxhat 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 bale of hay, striki87hf ko+;f2ay ioyz-gng the hay with a velocity oo 7f+ zf8ky;ygaiho2 -f 60 m/s. It penetrates a depth of 20 cm before stopping. What is the average stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m above a floofkgyx(,hi55h .qvjg; s5xso7 r to a height of 13.0 m above the floor. 5x q 5(vhogs;.,7yh5fxijgskWhat 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 plane is 4.0 m lo d;,z4r./akiln* qnolng and rises 2.0 m. If the plane is frictionless, *nnl 4/oal,. ;qkzdi rhow much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to stretch 2.0v4obkf+7 3;tphm dx u1 cm. What is the spring constfx +v h4od3kmtp bu1;7ant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m. Hywb(c;dt2j /j 6 xdo+/5olgbbow much potential energy does it store, when 5lc2d;o(/6bo/jy +xdgb j tb wstretched 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 required4tdpht/,v (cn 1dl fr: to compress an initially uncompressed spring with a spring constant of 25 N/h4ld,dtt n/fv (p1c r: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 spriag8yt.- dr7tccsb.w*o9 gl 8ang of spring constant 40 N/m from x = 0.20 m to 0.25 m? (Assume the dabg.8 ro9* -gsylwa.ct 78tcunstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N/m is initially compressed by 3.0 cm. Hoo a+m m;h1;48wxnmlwpm/yg2 j w much work is required to compress the spring an additw;8hm mxman2 w g/1y pjmol;+4ional 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 fromby98ra;un0cpy2c o, prlp c8xcj.7i; rest from the top of a 50-m high slope. What is the speed of the slierl8 .y 0pcba rcc,cj;y r2;upxpni7o9 8 on reaching the bottom of the slope? (Neglect 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 theq8 2.ya6 aowkr(h4n hw.uvo,a4pf: l s top of a hill with an initial speed of 4.0 m/s. Neglecting frictio8.4pw:hlo (2.uahsaqnavoy,kwr 6 f4 n, how fast will she be moving after dropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inclined plane. At the jo x;2;eva wy715by dnbottom, it has a speed of 9.80 m/s. Whaj5 w2advb7 o1x;eyy;nt is the vertical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m above the floor, its potenbnzb(p:y9y6sq)gi7 6 liba5c tial energy exactly eaz y b)i 6iql697b(spn :y5cgbquals 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 de(3u+pa-ej6a6 7brak1sj - /wrlfci N, blasts straight up from ground level with a kinetic energy of 40 J. At the exisej+ -63wj7/fe rab urac(a6-1lpk dact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the ground with a kinetic energyr bi2s k;mp;j9 of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to2k9rmsij p ;b; 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 the bottom of a dip) vvx+uut/tf. 6u( psb (See Fig. 6-2). Neglect friction, what will be the speed of the roller coasterpbutxs u fv6+)t(./uv at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at aub:wz k+it.h cnvts q5 5hvw:+x61+bd point 45 m above the bottom of a dip (See Fig. 6-2). Neglect frictionzvh+.q5ch :+xb61iwwkdvsb5+ tt nu:, 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 ab/5qrn0hk l .loove the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller con k.h/q5lrl0oaster 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 th 5 mnzk/9e5 ch rj-8kirte7l-9p1,3jfhydvr ie ball 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 j 8cq),xlj3r;n r6 nkw7mm q6cis pulled 30 cm away from the vertical axis and released from rest. What will be itmr7 6,krj nqljwn )3x6 8;cqmcs 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 ey.aluf p.:q. fa-z )dinitially uncompressed horizontal spring with spring constant la p- f).aq:.yud.efz 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 ca y)(gi6u;igye r to stop for a red light. What work is done by the friceuy )g iyg6i;(tion 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 ve:j8,eywc2lw swg*di;+zcuk(8 r -gsurface is 50.0*kwc w eugd(8le i r+z82y-sgc,:vjw; N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J of kdol0pp +decc + mu,wj8j:i rs9 d3m.k)inetic energy. The friction force on it is a constant 0.50 N. How far wilc)rj s 3:elp80kmd+m i.,+jd9udocwpl 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 hoq,(:kzv 0 tpzcc0k6yw/kxk m;,zp /o yrizontally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction kz6 ;(co, pkm qpxzy,z t0k:0cyv//wkbetween the mass and the surface 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 hp 2y(- ozwqe5rest from the top of a 50-m high slope. If the work doqoh2(z pw5ye-ne by friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined w6 n r(g1:orxeplane. 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 the br( reow:g1 6nxox?

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 fro.uxyfn1kh yml x.l6 1.hj h1)mm rest at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the p ln f1 6.1xyumljk hh1.ymhx.)lane 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 ground e9o)frqu4xk stl iy5j l-)17t with a velocity of 7.00 m/s. What average force of a jxf)l49ey -lu )s1tto rqk57iir 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 boy6h(fjd+- 9yycf8ufhp o60 tqq using energy when he runs up a flight of stairs 108-(+pj9hfcdf tq6fhy uyq o60.0-m 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 velocity of 5.0 m/skd1;yuij.u:etqbe f0. 6 2y du. Wha6:0 jf 2 e;. dbyi.eduyktq1uut power must be 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 by a 1.0 hp mo/(6du( g0:aj;r bmmqpa ajh r)tor that runs for 1.0 hr? (1 hp = j:armj0h6ma(gq /pbur(ad; )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 much fo0yg lo)9,oulx xiqz97qt ef jy+ j:7e0rce does her foot push with when she is traveling at 8.0 m/s?q+z got9uj7i)lo ,0 y fjq:ex0 exly97

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 th00swyci0oh- b e average power delivered by the engine? (1 hp = 74-s00iybh 0wc o6 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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