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

1#

What is the correct unit of work expressed in SI unit4du)jw;c;ti,caf / sfs?

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 mjtsv gd * -ixg,6efh/ dl(4gy4 l.ea7a system 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 stationar+0+cgcs bmv5x tj6ma +y brick wall, the amount of work you dmsv c++b0jgt5ac+xm6 o

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 li/ fhv5x c s6:m 0 (jmedm7ads*)-bcxqtfted 2.0 m vertically and is being held there. How much work is being d )smcdbcex5f/7th:(sm- x q 6vja0md*one in holding the box in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontpph i* e4,lv7yally forward at a constant velocity carrying a 10-N object, the amount ofl yep, *hvpi74 work you do is

A. more than 50 J.

B. equal to 50 J.

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

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted ver42g vz8 no.trrtically 3.0 m then returned to its original position. If the total weight is 30 N, how much work was.nr4otvz28g r 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 a/u,r goi:8.m bbyghv+g b(lt9 ae:+gv cting 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 the -n+ rj2bov:mfflx9/ qwork done by gravity while the ball goes up with the sign of the work done by gravity frqv j onf2m+-l9bx/: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 verrf/8, zsi+amzx 84ujrpn8w6i sus position (F vs. x) graph, represents8+u n/xizr ,jwza68s8pimf4r

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 reposx22s8 c j7nii c2ss:resents the work done by the forci :xinscs22js 87c 2ose 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 ygp) p:d3hkft, tvuf+tl -o35 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 object is negative, then the object's kinet sr0v:0i*mpfwyue1 (z ic 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, t/ncfug wt3 e+,*wc)rt hen the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much vf5uclf6jm-lbe n0**ie:2c a as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to thac nvf u6lj-ci 2*ee5mbl0:f*at of the car?

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

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

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

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

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has half the mass of car K. 9n hw1y)aey)l rwc57wThe kinetic energy9))whea yw cwnr l51y7 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 speed.* za/ 08li5mz;ntp 6iyyaqfth6v s9b;w xmo0, What is the ratio of the final kinetic energy to thev0 ofi 5 *,/pb;wzlatz yxysmn;906h8aim6tq 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 speeee6spx4t6t +fd of 5 m/s. If both objects have the same kinetic energtxpe e4f st6+6y, what is the ratio of 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 mz4ej;;w:ixyf72e k gp /s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant brak;if2;e xjk 4:e7gpwyz ing 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 distancej8uy/w**3 o(g tue; le diu(gq on a straight, level road. If you had been traveling twice as fast, what distance would the car uw/* it8;uggedyuq(joe (l 3 *have skidded, under the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elw( 4snw/u+ nsh8uihwx 1zi:jvp(s41qliptical orbit. Neglecting any friction effects, what happens to the planet's kinetic 4 wizvsu4i: hp1uxsn1 jn(hw/8s(q w+energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

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

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy principle. js)wwip 9a7z)v8/qw 3mwg-gg

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; kx^2$ is

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to have negative potential energy?yi :;uub)5s.a 5 h. xty,swyfq

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 p4ad-t.l/ d- p jsf ex2bz5u0cground. A second object with four times the mass of the first if released from the same height. The poten5f e .cs 2udtl-xpd jbpza/-04tial 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 t4ki b; cpo 1fvt)l9-c0oic1gspring causes it to stretch 5.0 cm. If another 0.200-kg mass fk1-0pt io 9vlg c1c4t);c biois 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 systemoif(9lb9 0bbv *3wyak 1j1 ziq

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 ener:5+dxy9ox5vf7mq +p: ++o a rzdfn;l fsini (agy K, to its potential energyxf f 5+li:anf;v5a :+mps7y9 +r(qd +donxo zi 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 c z:-+j 5c0t ;ygnl sbzrg72kadriving up a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object and a very heavy object are srt86hxbw +7d jf-ol93 z)/dystd p ep+liding with equal speeds along a level frictionless surface. They both slids p/7tyole d-+)fwbd 6rj8zp+tx h3 9de 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 ax+hi; g de:oui4a)p 9$m_{1}$ 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 enerplyvnv* -q62t gy for conservative forces.-*62 yqln pvtv

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 is a;w28nwumb x q - puf+f0xh5;jpresent), to the ground below. How does the kinetic energy (K) ju xfw 0ua-;qp5uhf+ ;2bnj8wx mst 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 anduu x 8u-;n qs(8wvx:0,deb)dl icggh+ gains 30 J of kinetic energy. Do not ignore air resicbxg;nu ud8 d,hx+gws) (0 e:q il8uv-stance. How much gravitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of graz(rakou(lu1 d0;a 1 yyvitational potential energy. Do not igk ( uodr(y;1u10zyaa lnore air resistance. 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 conservatio2 4cj 3htcnrr* 5g*3zbz +xiwsskuf7 /n of energy.

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is:jas.lh2 (j xia3v4t v

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 expressedzpjvfqyj3c((h1 w zmm 0b0/g8 bi6r*q 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 m r ic8gr.j +al6q(lmb7 k2sz9not 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 dib.h *2ob zylq3m6um s:d 3 times the work in one-third the time. To do so, yoqh3s*2umy6 b.: zlbomur power 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 constgcks xg9)(3;.rlfh h ,ts:elcant 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 th. m +u j sgstzbp2q- 6js-(tcvw6m,un*e object weighs 90 N, how much wvst us*j,6qtp(m.2uwsj -n- gb6 mzc +ork was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics book up in the air a distance of 1.0 m, at soq9s ;1b 1f: :qj6xrtj/e( g7v qdrkma constant velocity of 0.50 m/s. Wha : rdr:/x(s6m9tgkq ;vjeq1 j7qos bf1t is the 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 ef wv* c: 8w3ti4ckq838fzgrjwith a constant force of 5500 N for a distance of 50.0 m.8iqzk*3 t38jcvrwgec:4fw8 f What is 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 upward witsc.h;; bs6mjnh a constant force of 5500 N for a distance of 50.0 m. What is ;h s;b.6ncmsj 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 wi8y/;q9ytdt jkrx +orc2 v) qi7th a constant force of 5500 N for a distance of 50.0 m. What is the net work done o9 vdi;x tqc otr8r2qk+) j/yy7n 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 alon 9ytqk) kk6/h+s nwv7lhk1.fjg a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

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

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

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

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp, incl+nd(4(i+yu v cdhxzk bl47qh0 ined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

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

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on an icy surfacf)cv)d1f 7fjh e (assume no friction), with acf1f7)dh vjf ) 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 i25le*xv61klilk go4*mgh,v m n Fig. 6-1 shows the force versuk5 l24g ek,v*lmi 61g* hmxlvos the object's position. Find the work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. Tjd gc639xz-xwincw;r2 a b rq4d5l2(jhe graph in Fig. 6-1 shows the force versus the object's position. Find the work done w63 zbx-j9 (acn wqrdx5j2r 2lc4igdw;hen 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 dir,68e ryxth pi//jn,k rection of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the 6,r /,x8nheriy t jp/kwork 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 obje ee9;w3. eveowzzy w/4eh 3v7oct in the direction of the force. The graph in Fig. 6-1 shows the force versus the objeo e4 vz yz7eeeo we;ww/33.hv9ct's position. Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to move a 55-kg cart (initiallpdu)j 5,8m4x pt5 wksvmgoy00 y at rest) across a 10 m level surface. What is the ,5t5ju p8pdsm)0okv mg0wy4x 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-kg+ ddma5e7xb-v)7vgm c cart (initially at rest) across a 10 m level surfacbx v7-+medad5)gv 7cme. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much work is requm epnmob6ni8y ( t08 oax/8l:xy1ski-ired to stop thle8 mxn niyk 1opy 6(88i:0axo/bstm- e 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 distance is requ4d*zfkd3f 9 e(hjdu t6iref6 dk u43tfhd*(dzj 9ed to stop a car moving at 50 m/s under the same condition?

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels a 10srydg 6(y/z xwvhmr6( 90xdx 6-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With what speed will the dart leavev w(hx (/d69rxmxy6y drg0zs6 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 componentc*qy* 6 bxbtcwxu / ;*pov;h9r 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 starxtrcv;*bxwpc9h* *yb/ ;6 u qots from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontally into a bale of hay, stmt/qvbgxhh 8vf p5v.4 8z+.piriking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the pmvpq.x /v.ib h v8g z8ft+54haverage 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 fdk3,vlxhv8 k/g4 z dhefx1g:*rom a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in g/*z4vkhh8v31,e g : g dxdxlfkravitational 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 incw;vv n*km(4qslined plane. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionless, sn(;4qmk*v wvhow 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 thy1w 7wz;e4k.aozl gr3 b9iha 3e spring to stretch 2.0 cm. What is the spring constw4g 7.3azk9o13;yibrlhzw eaant?

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 conszl+wkv21/ j,v z7su t-jyh5v+swy n k.tant of 60 N/m. How much potential energy does it store, whenjz s 15,lnvyvh v2kj7/ww+-yzkt .su+ 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 uncomprep (5;2ic ih7/navmis xssed spring with a spring constant of c7n2(p5mxihi aiv/; s25 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 of spring constant 40 N/m from x =l oh 3 y/62qgv4c1qqm a5 a*v+gk3hbed 0.20 m to 0.25 m? (Assume the unstretched position is at x = 0.ggv mea+3q*/ hvdch qq3ba5k2o1 y64 l)

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 15on as 6(kq m48,c9zf rdw5k+ 3q0guewm N/m is initially compressed by 3.0 cm. How much work is required to compress the spring an ar3z6c5 q+mkan9udqww0s ,8mg f4koe( dditional 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. What 4hqxas 8hhykn ,+n2j 5nelo-yuo .9t*is the speed of the slier on reaching toy k4a+nj e9 nslytqx5,2-8.*nhohuhhe 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, po2vwa g,4z)(9a iykw4yx k2fmushes off the top of a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 10 m in elevation?zkayimy(92o va kw)424 g,xfw

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 bottob5hkouyni c2 iaxpewqo 5w -qt, 4+o588b(n n1m, it has a speed of 9.80 m/s. What is the vertical height of the plahi 4p o5qny-2+,x 8q(eb c 18iaoobnkw5t nwu5ne?

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. .*nhvmt,5bm mWhen it is 0.70 m above the floor, its potential energy exactly equals its kinetic energy.h m, *nt.5mvbm How fast is it moving?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts straight up from groundykfavs67*5gn level with a kinetic energy of 40 J. At the exacs* y 67v5afkngt 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 energy of 220x90a0wfn 5 u. b /3es(qbyqodp J. At the highest point in its trajectory, its ex w0qdona. b/py 5(9q0fb3su kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise?

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

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

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

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest atoj-xa1pvi7q5lx f .2j a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the f2 qipaj7-x.1o j5 lxvbottom 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 a point 45 m above thec p1yf9fogs45(b3tjt bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the p3otf(yf 5t9 bg14sj ctop 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 3e/4m5 n bn:vqm0 m above the bottom of a dip with a speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speede4qn/ 5m nmb:v 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 (ps-f*j4+ ;ov.ce:urn5/tysh c krkfj8oint

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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 5t7q)9ixrlnxib co43nm *0)j4wdeu 6 p0 cm is pulled 30 cm away from the vertical axis and released from rest. What will be its speed at the botx u)lp*4 ) mj4 ci7o rib60en9wqn3dxttom 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 a8q4- k:*s lxg) - oppwesjh0ainitially uncompressed horizontal spring with spring constanaoa-0qsswplepxj:k h4*- 8) gt 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, slo .ze *rz3,8 dp,uh(tgmmb0 czyws down her 2000 kg car to stop for a red light. What work isg3y0r (u8z*bpemzt,z,h .dc m 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)j2gdzp ux* s2t and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0 m/xd)jg p2uz2*ss, 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 7 ci :o(e)ku)qq( kt u/dz2julJ of kinetic ener :li 2k)c)ujt7/ z(d equko(qugy. The friction force on it is a constant 0.50 N. How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horihu +/c:docd 8/w-xo+ zis 0m iki1dt2wzontally to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the change inczcs wdotui-kx dm1/i /:0oh+ d+iw82 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 todx(ab294e84rcvon1a n d f3 php of a 50-m high slope. If the work done by ne8arxf( bdon44p1d9h2 ac v3friction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined plane. The pla;e pti ( 9-up8psnwwit)t2re.ne is 4.0 m long and rises 2.0 m. It rewstr-)8ptuinp9 pe;2 . (itwequires 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 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 releaft /y9 mdps ,txhw67k1u1cdd- sed from rest at the top of a plane inclined at 20e above horizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. -y1dhwupdc,/69x 7sdm ftt1k 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 grounddimxt ++i wn:*h15zld with a velocity of 7.00 m/s. What average force of air friction acts ow1h +:mdi* xi+zdn5tln it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a flight of 5-t9ns)stlfb stairs 10.9b5)- lf sntst0-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 conrul/ 6a8 lt02dobj 8t;po-bq fstant velocity of 5.0 m/s. What power must betjlb-fpt8 rdo b/8 u2;q60aol 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 bxa85qx z3 - vg ,w7hi9lhzf6vky a 1.0 hp motor that runs for 1.0 hr? (1 hp = 746 f-g5vi q 8l76xxkwvaz 9zh,3 hW)

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 oapf9;0uvb h/ ef 500 W while riding. How much force does her foot push with wh ep;bf 9h/a0vuen 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 -;y1y6o g+1l aanlorim/s in 7.0 s. What is the average power dl;aor-o 6y nl gi+1ay1elivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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