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习题练习:Physics Unit6: Work and Energy



 作者: admin发布日期: 2022-07-28 12:33   总分: 95分  得分: _____________

答题人: 匿名未登录  开始时间: 22年07月26日 13:45  切换到: 整卷模式

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1#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the correct uny/fodv4)bs23 q/p4chl fv4dq it of work expressed in SI units?

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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 there is n-qindzf v4k cte9 9d6q z9jn4-o motion?

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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 skoc5z2wd+(2dyl .opu tationary brick wall, the amount of work yo(c+2zuoo p ywdkl5.2 du do

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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 ve+ bdk5e5q06pw2d;c-kzmkgnu up3 i9e rtically and is being held there. How much work is being done in holding the box in tegm6e3 5+9-2 k;ud0cp w5z dkpqb inukhis position?

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5#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  If you walk 5.0 m horizontally forward at a constant velocit/er.h(gn.zkf01d a rky carrying a 10-N objern1kdke0 .a(g ./zr hfct, the amount of work you do is

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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 its3:(iig v8a;xi v6dnh.9s jyel original position. If the t i ;8(3i hnx96dvjv.:gislaey otal weight is 30 N, how much work was done?

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7#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Does the centripetal force acting on an object do work on the objectnidgkx ,4b/1uxike g63n8w8 s ?

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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 to1v ocgh a ;26u p5v4mir)svj6he work done by gravity while the ball goes up with the sign of the work done by gravity wip5;ar6g)vu2ov1o v 4 6hmjschile it goes 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 posiuesz. gpu*)ol+sk */ ction (F vs. x) graph, representsgcskpz )o* e+l/. *suu

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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)ytkdik.)g0c u)2l)nrp 9n xe work done by the f )pn)icgk y9et uxn.lk 20r))dorce F?

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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

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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 o rdl)ak6 usym/n gn*,*+ od4 ;ezw-fdfbject is positive, then the object's kinetic energy

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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 kintyeq;h0c8 ze n 0/u.cdk a(;uvetic energy

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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*aj8 sw0oe-u k kinetic energy

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15#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A truck weighs twice as much as a car, and is movixt94gxa:l 6jh ng at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that ha9xg t4j l:x6of 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. The-apisycrq188k9 v r1 g kin 8cgyi11-8 qpk9v sarretic energy of car J, compared to car K is

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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 wallk;af u6 zgwn09 and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the n fug;0ka9 z6winitial kinetic energy?

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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 ofh).h1wjk: eoi 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass joih :.)1w kheto the rock's mass?

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19#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 4.0-kg mass is moving with speed 2.0 m/s. A 1.0-kg m +8y7tv.pdztq- w) rzcass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. t zz)rp-t+v .cd y78qw Which object travels the greater distance before stopping?

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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 yop)cz*yy x-)q 2ahdum/ ur 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 a*cx ) 2yzud/y)hm-qp the car have skidded, under the same conditions?

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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+ pktytnq/5n. orbit. Neglecting any friction effects, what happe k. p/nyqn+t5tns to the planet's kinetic energy?

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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 pri)prr7 bbt: jg+nciple.
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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

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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

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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 potentialq .;c*;o*fuv s cyphj9 energy?

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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 restb6sdeu*o gu :8ejt +:d a height h above the ground. A second object with four times the mass of the first if released from the same height. The potential energy of the so6 d dje8teub*:+:sguecond object compared to the first is

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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 attacheaj2zj.bciv4:xe m2;( tmb 2ard to the end of a spring causes it to stretch 5.0 cm. If another 0.200-kg mass is added to the spring, th j b:v22j 4.ma2 b(ciztxarme;e potential energy of the spring will be

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28#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The total mechanical e a4 u 1ae;:gilq5dp flnpx6q-0l9uv* anergy of a system

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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 trenvj-t z /+*xib68gzu;ygp b 9qe. Compare its kinetic energy K, to its potential energy U./b-i6t ubz 9 z+*xjggqyvpn8;

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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 drivivvgb7vrbo.j)t 16fz: ng up a hill.

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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 objeci6viyw;is/ ,t t are sliding with equal speeds along a level frictionless surface/,t is vwi6yi;. They both slide up the same frictionless hill. Which rises to a greater height?

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32#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Consider two masses ;c x(p-t-toz.us,a29pqs kmyq1th3y $m_{1}$ 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?

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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 consex5h jth*n.-e,d lnmtlp +s3e(rvation of mechanical energy for conservative forces.e,je.3nmhsnt h(5-+p *dtlx l
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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 friom bo3n2:6do oction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compare to the potential omo:62noob3d energy (U) at the top of the building?

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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 kink+ z0nx 06gsw2*eeof3/ri wfnetic energy. Do not ignore air resistance.i +nwg06z2x frw /*0ksenf3 oe How much gravitational potential energy did the ball lose?

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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 Jf v rfoas dcavr;2r4:*8 qt60yt5zj 0v of gravitational potential energy. Do not ignore air resistance. How much ki r0*; 0art: vts5rvyo jqv 6z84fafc2dnetic energy did the ball gain?

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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 conyub90ki)vpv poe4(y, 5 qr6nmservation of energy.
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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 thnju(j7p l:*

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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 powerevx1w *- nnx+5wf2h lo expressed in SI units?

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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 nzhob, ;3poys ,z*2dfnqva/4 qot a unit of power?

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41#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Compared to yesterday, you did 3 tim2jbqvp33:dw fes the work in one-third the time. To do so, your power outpqjd:3pwfvb32 ut must have been

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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 accoo6t8mf k/t 2u6iz(g d0it.l xeleration, the car's engine must

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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 nkfv z.f3jwa64x i6p 5object weighs 90 N, how much work was done in liftinv4p jn3xwif.a656fz kg it?

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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 giw,(iuh e++to +bb1z )t.*okt ggqd8book up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the (+zuo, ggo+)t8.h q dk*i btgbit1we +work done by the weight of the book?

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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 force9z pve-bncuu0* x.jzlr:4cp+ of 5500 N for a distance of 50.0 m. What is the work done by thn9ez bjc .0cv p-lpxu z*ur4+:e 5500 N force?

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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 of 5500 z,lpu +ba,d1h N for a distance of 50.0 ma+,d ul,zphb 1. What is the work done by the weight of the elevator?

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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 forqo;vs (b 9jcp3ce of 5500 N for a distance of 50.0 m. What is the net woroq(cs p9jv;3bk done on the elevator?

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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 upnewh;ba-e. 1 xr fx53j :fdh4i along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

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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 dow/ j 8bsqq8,vm fgj(7wvn 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?

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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 surface (assume no f6b/th;hhdok z: fjg84 riction), with a force of 60.0 N at an angle ob8z ;6:jhh4 otk/gd hff $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

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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 directio:u .sbi8+n,(atdtsih n of the force. The graph in Fig. 6-1 shows the force versus the object's position. Find the work done when the o. uts siab,:8t+ dnhi(bject moves from 0 to 2.0 m.


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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 direcsy;qf) 7qiy,vz s hl2gj7(y9rtion of the force. The graph in Fig. 6-1 shows the force versus 7),2fyv;hsg9 y rsz7qy j il(qthe object's position. Find the work done when the object moves from 2.0 to 4.0 m.


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53#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A force moves an object in the direction of the force. The graph ij e6q0vs5d* evur;lc5n Fig. 6-1 shows the force versus the object's position. Find the work done when the object moves from 4.0 to *l ejd05seurc qv5v ;66.0 m.


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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 ofg4:ll9w 9edix 7hve-f the force. The graph in Fig. 6-1 shows the force ve9d4i wf:g vl 7le9x-ehrsus the object's position. Find the work done when the object moves from 0 to 6.0 m.


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55#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A horizontal force of1s, u*ytcz2mo:n 5xih 200 N is applied to move a 55-kg cart (initially at rest) 5hx,cztu*i s2: 1my onacross a 10 m level surface. What is the final kinetic energy of the cart?

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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 a 8 i;rgsa3)q*cq0uu7j 5xz rgN is applied to move a 55-kg cart (initially at rest) across a 10 m level surface. What is the final sgarx;5)8 q3*c0jzaqgi u s7r upeed of the cart?

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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. ;bd mt /*rh5kmig.b) e How much work is required to stop t m/d)m 5*rk bi;eg.hbthe mass?

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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 hhb,mo:0fy:.a7 cw3px vz)mlstop a car initially moving at 25 m/s, what distance is required to stop a car moving at 50phm7 )yb vx:awhf: , m.clo3z0 m/s under the same condition?

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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 propelnne:2c0 .k,oyp/nn 7n* nqfnis a 10-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 len/n.*n:7ey,o n0innp qf2n k cave the gun, assuming the spring has negligible mass?

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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 vert 2n1jhr:qll0r i5)v 84trkkcsgt/f *h ical 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 jv:h5 8)gr srkth/4*clnqtrk1 i2 l0fis the cart's final kinetic energy?

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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 znz q y 5h988))xqkwgtg is shot horizontally into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20) 8k8xw t zg95yzqnq)h cm before stopping. What is the average stopping force acting on the arrow?

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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 fro .byqkf7atn :2m a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitationalt2y: .7a kfbqn potential energy?

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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 jo5b 1zjmamt q17xb3*5 h:oqy plane is 4.0 m long and rises 2.0 m. If the plane is fr1 :b15hqyq3jo ztom* j ab57mxictionless, how much work was done by the push?

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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 24; ;6oxzuw .gpr/ yo n(qc-z c9mck:ef.0 cm. What is the sprinoc zrz k /uyc.x49cqeg6(:o fp;m -wn;g constant?

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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. /72w ww:wflcyHow much potential enerwl27w/f: wy wcgy does it store, when stretched by 1.0 cm?

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66#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the work required to compress an initially uncompressed m7*llfwcgq1: spring with a spring constant of 25 N/m by 10 1lgq7f:ml* cwcm.

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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 =a q;hog-t+-m/ te j(fd 0.20 m to 0.t/q(deo+;m-jag t-fh25 m? (Assume the unstretched position is at x = 0.)

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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 compressedp j xuoc9nytw2 *jen-y1b ;;;q by 3.0 cm. How much work is required to compress oj19x;*ebnpw y q-j;n yu2c; tthe spring an additional 4.0 cm?

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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 y,dp9ho 5 )moiyyi18wrest from the top of a 50-m high slope. What is the si5) 8y9 yhd ,pmoi1wyopeed of the slier on reaching the bottom of the slope? (Neglect friction.)

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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 initi7u6huzh6 wte9l x,z t9al speed of 4.0 m/s. Neglecting friction, how fast will she be moving after dropping 1h7,eu9t lxztu9 w 6z6h0 m in elevation?

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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 inclinn i b.qw,wdgx+-dx; 3aed plane. At the bottom, it has a speed of 9.80 m/s. What is the vertica-,xd.wd3qb gwaix +;n l height of the plane?

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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 ggex10 wlig4 v4a67tkit is 0.70 m above the floor, its potential energy exactly equals its kinetic eneig7v0 l6xk4wg 4at1 gergy. How fast is it moving?

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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 with a kineti1/xi wbf5)wdzb7 :v rn0,vywwc energy of 40 J. At the exact top of its trawx/ dv5ww,z)wi01 7 bbrfv y:njectory, its total mechanical energy is 140 J. To what vertical height does it rise?

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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 en8x 6rd s qqrvc49)ie3kergy of 220 J. At the highest point in its trajectory, its kinetic energy is 1q3) xrqvid6re 948k sc20 J. To what vertical height, relative to its launch point, did it rise?

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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 poiny.*ngeru b271g1k*v.d; gc ravw7n ao t 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 slopegv*w .17ydavr oa*n .cern b;7gu1k2g , which is 30 m above the bottom of the dip?


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76#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A roller coaster starf cp,vhf-a5z4 ts with a speed of 5.0 m/s at a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slopevzhaf4 , -fcp5, which is 30 m above the bottom of the dip?


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77#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A roller coaster starts at a point 30 m above the bottom of a dip with a /v1mzbm, 7)okc zb b7espeed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster ave 77z,zb/mcb) b1mko t the top of the next slope, which is 45 m above the bottom of the dip?


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78#
 
  What is the minimum speed of the ball ad;9o9gifqa vm1 2s* oht 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

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80#
 
  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 awcu8 pb;bqgjoo-9 9w7xay from the vertical axis and released from rest. What will be i7 j xb9- qcuw8gb9;oopts speed at the bottom of its swing?

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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 zb-z tbkk g( 1*:jcrl3-evu4 l-8yyv*k5i wet25 m/s hits an initially uncompressed horizontal spring with spring cey wl ebykic8 : vl-*(vrb31t5 uzg4*-jkzt-konstant of $2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

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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, s t7s6sv6yl)sz as;ktg8 u, se1lows down her 2000 kg car to stop for a red light. What work is doss1gt8 tuye ls)a zkv6ss,; 67ne by the friction force against the wheels?

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84#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The kinetic friction fq1ij *uzo+;d 175( yekehgygsorce between a 60.0-kg object and a horizontal surface is 50.0 N. If the initial speed of the object is 25.0uo+dz7e j1k1hy s;qi 5egy (g* m/s, what distance will it slide before coming to a stop?

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85#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 12-kg object is moving on a rough, level surface. It has 24 J of kinetic v/* 8qwl1lyf .7 s(blm)5nim m6vwf zuenergy. The friction force on it is a constant 0.50 N. How sim7mly8nv * um /1. lwfl6wbvqz(f5)far will it slide?

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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 levelqf zzz(0brr76 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 in its q(zr0 z7f6zb rkinetic energy?

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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 higun 8rqx-j)ad9 h slope. If the work done by frjad 8)-9uxq nriction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

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88#
 
单选题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An 800-N box is pushed up an inclined plane. The plane x6g3:v+e ei jv)gsjz: 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 for x :jesz36:iv)v egj+gce on the box?

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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 2z/2r:r;d0ad e 0q4d6kzen jzg0e above dz0 nerd q64z0ajgk2;e :r/zdhorizontal. The coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

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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 stri o.kljr tqx-)d+8u7t ukes the ground with a velocity of 7.00 m/s. What average force of air friction acts on it as it f78 txr)+ ud-.tjukqo lalls?

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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 wheno. joq w;s)gv+,sjo- w he runs up a flight of stairs 10.0-m hwsj+;.)jqo- ,v os owgigh, in
8.00 s?

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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 veloqnsbiz57 y 268kicsc /city of 5.0 m/s. What power must be delivered to the oys/b 7 nk ii86c5sz2cqbject by the force?

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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 fo ormy fh,uc0zd; a89o;r 1.0 hr? (1 hp = 7,o0crya; m u89oz h;df46 W)

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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 mm-f mpg(c/gd 6uch force does her footmd6c /m(g-pgf push with when she is traveling at 8.0 m/s?

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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. g7fv7sq6zf qnv095 e fgg0r.h+pd8o r0 s. What is the average power delivered by the engine? q80gfg6 r7.09epfn g 7qshfzovdrv+5 (1 hp = 746 W)

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