题库网 (tiku.one)

 找回密码
 立即注册

 

      

上传图片附件

未使用图片

小贴士: 允许的图片文件格式为: gif, jpg, jpeg, png, webp,上传完成后会在上方生成预览,用鼠标连续双击缩略图,或拖动缩略图,该图片就被绑定至本题,显示在题目下方

本次作答已使用

小贴士: 此栏目显示的是当前作答使用的所有图片,绑定到某一题目的图片同时会显示在该题目下方; 删除使用的图片会将其转移到<未使用图片>类别


习题练习:Rotational Motion



 作者: admin发布日期: 2024-12-27 14:40   总分: 110分  得分: _____________

答题人: 匿名未登录  开始时间: 12月27日 14:40  切换到: 整卷模式

标记此题
1#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A bicycle odometer (which measures distance traveled) isnyf88,bohj p k)h. 2 cr/;vgz +mfb5fo attached near the wheel hub and is designed for 27-inch wheels. What happens if you use it on a bicycle wiyfmhg, obb;p 2+nz58 .ohffc/jrk )8 vth 24-inch wheels?
参考答案:    

标记此题
2#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Suppose a disk rotates at constant angular velocit,3d;,l*j tif y pcqpuli/ -au5y. Does a point on the rim have radial and/or tangential acceleration? If the disk’s angular velocity increases uniformly, does the poitu3f- pyi,l;5d*c /palu ijq,nt have radial and/or tangential acceleration? For which cases would the magnitude of either component of linear acceleration change?
参考答案:    

标记此题
3#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Could a nonrigid body be described by a single valuf9a6r*ne4p7hzo,r9k cwdv8 c e of the angular velocity $\omega$ Explain.
参考答案:    

标记此题
4#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Can a small force ever exert a greater torque than a larger force? Expla avr7g.pc+;yjf4 icp:ll2:brin.
参考答案:    

标记此题
5#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
If a force $\vec{F}$ acts on an object such that its lever arm is zero, does it have any effect on the object’s motion? Explain.
参考答案:    

标记此题
6#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Why is it more difficult to do a sit-up witj xomk l cb(3,w;1u(iah your hands behind your head than whelm(1,oc 3abwi j( xku;n your arms are stretched out in front of you? A diagram may help you to answer this.
参考答案:    

标记此题
7#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A 21-speed bicycle has seven sprockets at the rear wheel ay ((/ea2mf fnend three at the pedal cranks. In which gear is it harder to pedal, a small rear sprocket or a large rear sprocket? Why? In which gear is it harder to pedal, a small front m /2((fafeyensprocket or a large front sprocket? Why?
参考答案:    

标记此题
8#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Mammals that depend on being able to run fast have slender lower legs with j/: wyfiu;bl8flesh and muscle concentrated high, close to the body (Fig. 8–34). On the basis of rot8uj:lfwiy/b ;ational dynamics, explain why this distribution of mass is advantageous.
参考答案:    

标记此题
9#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Why do tightrope walkers (Fig. 8 8+i)rul) 6h dab8;nj,xvb plc–35) carry a long, narrow beam?
参考答案:    

标记此题
10#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
If the net force on a system is zero, is the net torque also zero? If thes81f xws *yo;pk u-e4u net torque on a system is zero, is the net f1xe;8s *oy -us 4wkpfuorce zero?
参考答案:    

标记此题
11#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Two inclines have the same h5x8dvy2x v,jk* su*eeeight but make different angles with the horizontal. The same steel ball is rolled down each incline. On which incline will the speed of the bx*,ee svj5dyu 8x*v 2kall at the bottom be greater? Explain.
参考答案:    

标记此题
12#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Two solid spheres simultaneously start rolling (fr9zdfzliob5ac i2/ y 7:om rest) down an incline. One sphere has twice the radius and twice the mass of the othiy z2z 9 fb5c7o/i:alder. Which reaches the bottom of the incline first? Which has the greater speed there? Which has the greater total kinetic energy at the bottom?
参考答案:    

标记此题
13#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A sphere and a cylinder have the same radius and the same mass. Theymb x5w/4f)hanhiq zf.madr/,;c j 1n3 start from rest at the top of an incline. Which reaches the bottom first? Which has the greater speed at the bottom? Which has the greater total kinetic energy q x ,ffb hdn3w1zir /c 5h4na/;.am)mjat the bottom? Which has the greater rotational KE?
参考答案:    

标记此题
14#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
We claim that momentum and angular momentum are conserved. Yet most movinb;e6a f;z (vjy *zw)00 klcvxuze/f*qg or rotating objects ezkcay(u)feqv f;0zxb;w 6*l*0zv/jeventually slow down and stop. Explain.
参考答案:    

标记此题
15#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
If there were a great migration of 5u -yagp 130ldmrunt*people toward the Earth’s equator, how would thisnag 0 m*3yrt5l1-up ud affect the length of the day?
参考答案:    

标记此题
16#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Can the diver of Fig. 8–29 do a somersault without havingx6y3 6p;mbv4 :zxypig any initial rotation when she leaves ty6pxzgx m6v:; ip3 4ybhe board?
参考答案:    

标记此题
17#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The moment of inertia of a rotating solid disk about an axis through itsrfi r+4 tbwy:* center of mas:f rw4try *bi+s is $\frac{1}{2}WR^2$ (Fig. 8–21c). Suppose instead that the axis of rotation passes through a point on the edge of the disk. Will the moment of inertia be the same, larger, or smaller?
参考答案:    

标记此题
18#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Suppose you are sitting on a rotating st2r 9aq8vx2j rx 4,seqdool holding a 2-kg mass in each outstretched hand. If you suddenly drop the masses, will your angular velocity increase, dxrqrdq,j ea2 2xs 98v4ecrease, or stay the same? Explain.
参考答案:    

标记此题
19#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Two spheres look identical and have the same mass. However, one is hodgw6cr 3(4d nnnqw );ollow and the other is solid. Describe an experimeno4dwn3(6);n wdnc rqgt to determine which is which.
参考答案:    

标记此题
20#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
In whatdirection is the Earth’s angular velocity vector as it rotates daily about itsaxis?
参考答案:    

标记此题
21#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
The angular velocity of a whe .q3f*qw 8fvlpel rotating on a horizontal axle points west. In what direction is the linear velocity of a point on the top of the wheel? If the angular acceleration points east, describe the tangential linear acceleration of this point at the top of the wheel. vfq8pwf l.3q *Is the angular speed increasing or decreasing?
参考答案:    

标记此题
22#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Suppose you are standing on the edge,o ac:ymuf54z .djz)y of a large freely rotating turntable. What happen:,ca zzod5 um)4yj.yfs if you walk toward the center?
参考答案:    

标记此题
23#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A shortstop may leap into the ai sxv/6lv *x:fxr to catch a ball and throw it quickly. As he throws the ball, the upper part of his body rotavfx6 xvx: */sltes. If you look quickly you will notice that his hips and legs rotate in the opposite direction (Fig. 8–36). Explain.
参考答案:    

标记此题
24#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
On the basis of the law of conserv2 *l** mstrodyation of angular momentum, discuss why a helicopter must have more than one rotor (or pr*mst *r2 l*dyoopeller). Discuss one or more ways the second propeller can operate to keep the helicopter stable.
参考答案:    

标记此题
25#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Express the followin0c qk:w e9efa5g angles in radians: (a) 30 $^{\circ} $, (b) 57 $^{\circ} $, (c) 90 $^{\circ} $, (d) 360 $^{\circ} $, and (e) 420 $^{\circ} $. Give as numerical values and as fractions of $\pi$.(Round to two decimal places)
(a)   $rad$ (b)   $rad$ (c)    $rad$ (d)    $rad$ (e)    $rad$

参考答案:     查看本题详细解析

标记此题
26#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Eclipses happen on Earth because of an amazcwifh) gc 1hppuu3/hh3q (6l8ing coincidence. Calculate, using the information inside the Front Cover, the angular diameters (in radians) of the 1/( qulh63c)wphc fp3ihu g8hSun and the Moon, as seen on Earth.
Sun =    $rad$ Moon =    $rad$

参考答案:     查看本题详细解析

标记此题
27#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A laser beam is directed at the 8 1mhuvga5s1aMoon, 380,000 km from Earth. The beam diverges at ahgsa5a v 81u1mn angle $\theta$ (Fig. 8–37) of $1.4\times10^{-5}$ rad What diameter spot will it make on the Moon?    m



参考答案:     查看本题详细解析

标记此题
28#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The blades in a blender rotate at a rate of 6500 rpm. When the motor is t8dyp4 l/ m:mmiurned off during operation, the blades slow to rest in 3.0 s. /y 4 mdmlmi8:pWhat is the angular acceleration as the blades slow down?    $rad/s^2$

参考答案:     查看本题详细解析

标记此题
29#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A child rolls a ball on a level floor 3.5 m to another child. u,it5e1y t:wg k)s tv)If the ball makes 15.0 revolutions, what is its diamete1yet t 5:uw vkgt)i,)sr?    m

参考答案:     查看本题详细解析

标记此题
30#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bicycle with tires 68 cm in diameter travels 8.0 km. How many revolutions do t0we dcwxw0 ;v:c 4g2u*lsplu( hex;* 0(lw4:c dgu0vlce uspw2w wheels make?    $rev$

参考答案:     查看本题详细解析

标记此题
31#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) A grinding wheel 0.35 m in diameter rotates at 2500 rpm. Calculate its angull m 9 ck ka+rtyonvs(o61bl551ar velocityok+l6vs9t5bn( rk1a15mc o ly in $rad/s$ $\omega$ =    $rad/sec$
(b) What are the linear speed and acceleration of a point on the edge of the grinding wheel? v =    $m/s$ $a_R$ =    $ m/s^2$

参考答案:     查看本题详细解析

标记此题
32#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A rotating merry-go-round ma+r- vbx, oq u:4qe5wo9p5 v)zk)majot kes one complete revolution in 4.0 s (Fig. 8–38). (a) What is the k :jo5uwz)pqovbt+m eq-)xr5, 4va9 olinear speed of a child seated 1.2 m from the center?    $m/s$
(b) What is her acceleration (give components)?    $m/s^2$    the center

参考答案:     查看本题详细解析

标记此题
33#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the angular velocity of the Earth (a) in 9gb7x( psh:nfits orbit around the Sun    $ \times10^{-7 }$ $rad/s$
(b) about its axis.    $ \times10^{-5}$ $rad/s$

参考答案:     查看本题详细解析

标记此题
34#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the linear speed of a pointe) v.z vss;cdfik-l+.
(a) on the equator,    $m/s$
(b) on the Arctic Circle (latitude 66.5$^{\circ} $ N),    $m/s$
(c) at a latitude of 45.0$^{\circ} $ N, due to the Earth’s rotation?    $m/s$

参考答案:     查看本题详细解析

标记此题
35#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  How fast (in rpm) must a centrifuge rotate if a particle a g 7t9d)v3jru7.0 cm from the axis of r3ga9u t )7djvrotation is to experience an acceleration of 100,000 $g’s$?    $rpm$

参考答案:     查看本题详细解析

标记此题
36#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 70-cm-diameter whe mtf6,i03eemrg/rf 6qel accelerates uniformly about its center from 130 rpm to 280 rpm in 4.0 s. Determine m i,0gerfe f6qmt6/r3
(a) its angular acceleration,$\approx$    $rad/s^2$(Round to one decimal places)
(b) the radial and tangential components of the linear acceleration of a point on the edge of the wheel 2.0 s after it has started accelerating. $a_R$    $m/s^2$ $a_{tan}$    $m/s^2$

参考答案:     查看本题详细解析

标记此题
37#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A turntable of radius :g-v9gxh/s z ;khtt 5ne(k c4x$R_1$ is turned by a circular rubber roller of radius $R_2$ in contact with it at their outer edges. What is the ratio of their angular velocities, $\omega_1$ / $\omega_2$
参考答案:    

标记此题
38#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  In traveling to the Moon,3.*v 7t.wznk qx.xsc01i nyg:j;fe zi astronauts aboard the Apollo spacecraft put themselves into a slow rotation to distribute the Sun’s energy evenl z7fi.iqy:;xgtn sw0 *v.ec1k z3.nx jy. At the start of their trip, they accelerated from no rotation to 1.0 revolution every minute during a 12-min time interval. The spacecraft can be thought of as a cylinder with a diameter of 8.5 m. Determine
(a) the angular acceleration, $\approx$    $rad/s^2$
(b) the radial and tangential components of the linear acceleration of a point on the skin of the ship 5.0 min after it started this acceleration. $a_{tan}$ =    $ \times10^{ -4}$ $m/s^2$ $a_{rad}$ =    $ \times10^{ -3}$ $m/s^2$

参考答案:     查看本题详细解析

标记此题
39#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A centrifuge accelerates uniformly from rest to 15,000 rpm in- 0d rpo olboqv//,+lp 220 s. Through how many revolutions did it turn in tpb+q,d /-lo oporlv/0his time?    $rev$

参考答案:     查看本题详细解析

标记此题
40#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An automobile engine slows down from 4500 rpm to 1200 rpm zheg 9pp*m*+j-+grs yc v2un3in 2.5 s. Calculate
(a) its angular acceleration, assumed constant,    $rad/s^2$
(b) the total number of revolutions the engine makes in this time.    $rev$

参考答案:     查看本题详细解析

标记此题
41#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Pilots can be tested for the stresses of flyin(hy f. 8nfizkz yi/v:5g highspeed jets in a whirling “human centrifuge,” which takes 1.0 min to turn through 20 complete revolutions beforehf/z.85 iyin vzkf :(y reaching its final speed.
(a) What was its angular acceleration (assumed constant),    $rev/min^2$
(b) what was its final angular speed in rpm?    $rpm$

参考答案:     查看本题详细解析

标记此题
42#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A wheel 33 cm in diameter accelerates uniformly from 240 rpm to 360 rcp0zd g0;x/a lpm in 6.5 s. How far will a pox z;lcap00g/d int on the edge of the wheel have traveled in this time?    m

参考答案:     查看本题详细解析

标记此题
43#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A cooling fan is turned off when it is running at 850rev/min Iff/+ty6 x389zsu:3 c yjxlsqft turns 1500 revolutions before it comes to a 3ffsz: t9y36j8uxx +yqlfs/cstop.
(a) What was the fan’s angular acceleration, assumed constant?    $\frac{rad}{s^2}$
(b) How long did it take the fan to come to a complete stop?    s

参考答案:     查看本题详细解析

标记此题
44#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The tires of a car make 65 revolutions as the car reduces its speed uniform2:-y 2 jyuot+mmzq:m j ktfb+(ly from 9o q2j k+fu- 2(y mjz+:tbtm:my5km/h to 45km/h The tires have a diameter of 0.80 m.
(a) What was the angular acceleration of the tires? $\approx$    $rad/s^2$
(b) If the car continues to decelerate at this rate, how much more time is required for it to stop?    s

参考答案:     查看本题详细解析

标记此题
45#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The tires of a car make 65 revolutions as the car reduces its speed uniformlyq -glni ,-qkoz:kw(20egc ws- from 95km/h to 45km/h The ti2c,i -nle- 0g-oz qkq(s:g wwkres have a diameter of 0.80 m.
(a) What was the angular acceleration of the tires? $\approx$    $rad/s^2$
(b) If the car continues to decelerate at this rate, how much more time is required for it to stop?    s

参考答案:     查看本题详细解析

标记此题
46#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 55-kg person riding a bike puts als e;ktl q y tvfuz28tb7657zv c187fbul her weight on each pedal when climbing a hill. The pedals rotate u8cz1 6 et;5lufbz2 7bty7tvvkq 8f s7in a circle of radius 17 cm.
(a) What is the maximum torque she exerts?    $m \cdot N$
(b) How could she exert more torque?

参考答案:     查看本题详细解析

标记此题
47#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A person exerts a force of 55 N on the end of a door 74 cm wkps qvbmib8/n,.f93o3( vd nfide. What is the magnitude of the torque if the force is kf9nsvo8,bfp vd3i/n( bq3.mexerted
(a) perpendicular to the door    $m \cdot N$
(b) at a 45 $^{\circ} $ angle to the face of the door?    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
48#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the net torque about thevt./vm o2t/k r axle of the wheel shown in Fig. 8–39. Assume that a frict rttvvm2.k//o ion torque of 0.4 $m \cdot N$ opposes the motion.    $m \cdot N$  



参考答案:     查看本题详细解析

标记此题
49#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
Two blocks, each of mass m, are att,66rc 17ow5gorx a5 xe5kq vtkached to the ends of a massless rod which pivots as shown in Fig. 8–40. Initially the rod is held in the horizontal position and then released. Calculq, awoogk5r5x 6vx6e 15ck rt7ate the magnitude and direction of the net torque on this system.
参考答案:    

标记此题
50#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The bolts on the cylinder head of an ev*mtr69j:puo 3 p(zyvr w/7i nngine require tightening to a torque of 38 rwpo(7uv j z3nr6it y:p*/ mv9$m \cdot N$ If a wrench is 28 cm long, what force perpendicular to the wrench must the mechanic exert at its end?    N
If the six-sided bolt head is 15 mm in diameter, estimate the force applied near each of the six points by a socket wrench (Fig. 8–41).    N


参考答案:     查看本题详细解析

标记此题
51#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Determine the moment o--8ix/y.csfjhg -cn l f inertia of a 10.8-kg sphere of radius 0.648 m when the axis of rotat-gnx l f/i8yc-j.c- hsion is through its center.    $kg \cdot m^2$

参考答案:     查看本题详细解析

标记此题
52#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the moment of inertia of a bicycle wheel 66 (+32 hzyv9qpf0x d:fpsztmd9 .7 cm in diameter. The rim and tire hazxt+dm qf 209sf:y (dpvph9z3ve a combined mass of 1.25 kg. The mass of the hub can be ignored (why?).    $kg \cdot m^2$

参考答案:     查看本题详细解析

标记此题
53#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A small 650-gram ball on the end of a thin, light rod is rotated in a horizon k2u3nrgm:zq - 1*zbrqtal circl*ng k3qu zmrr 21:-bqze of radius 1.2 m. Calculate
(a) the moment of inertia of the ball about the center of the circle,    $kg \cdot m^2$
(b) the torque needed to keep the ball rotating at constant angular velocity if air resistance exerts a force of 0.020 N on the ball. Ignore the rod’s moment of inertia and air resistance.    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
54#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A potter is shaping a bowt gvnr8 d63mo.l on a potter’s wheel rotating at constant angular speed (Fig. 8–42). The friction force betw6t.mv8o 3n drgeen her hands and the clay is 1.5 N total.
(a) How large is her torque on the wheel, if the diameter of the bowl is 12 cm?    $m \cdot N$
(b) How long would it take for the potter’s wheel to stop if the only torque acting on it is due to the potter’s hand? The initial angular velocity of the wheel is 1.6 rev/s, and the moment of inertia of the wheel and the bowl is 0.11 $kg \cdot m^2$.    s

参考答案:     查看本题详细解析

标记此题
55#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Calculate the moment of inertia of the array of point obo;*rtii lizu,(hymz p lc:3 /(jects shown in Fig. 8–43 abouii, czi z(:mr uho/(; tlyl*3pt
(a) the vertical axis,    $kg \cdot m^2$
(b) the horizontal axis. Assume m=1.8 kg,M=3.1kg and the objects are wired together by very light, rigid pieces of wire. The array is rectangular and is split through the middle by the horizontal axis.    $kg \cdot m^2$
(c) About which axis would it be harder to accelerate this array?



参考答案:     查看本题详细解析

标记此题
56#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An oxygen molecule consists of *bbn.: a;d6)bdav t rqtwo oxygen atoms whose total mass is $5.3 \times10^{ -26}$ kg and whose moment of inertia about an axis perpendicular to the line joining the two atoms, midway between them, is $ 1.9\times10^{-46 }$ $kg \cdot m^2$ From these data, estimate the effective distance between the atoms.    $\times10^{-10 }$ m

参考答案:     查看本题详细解析

标记此题
57#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  To get a flat, uniform cylindrical satellite spinning at the correct3w ne3haal3m . rate, engineers fire four tangential rockets as shown in Fig. 8–44. If the satellite has a mass of 3600 kg and a radius of 4.0 m, what is the required steady force oan3m3wl .ae3h f each rocket if the satellite is to reach 32 rpm in 5.0 min? $\approx$    N(round to the nearest integer)


参考答案:     查看本题详细解析

标记此题
58#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A grinding wheel is a uniform ctxty)khe6pmr 4 4 ahp xg+.(3oylinder with a radius of 8.50 cm and a mass of 0.5803 tgxo eyhp4(x.h rkm ap)46+t kg. Calculate
(a) its moment of inertia about its center, $\approx$    $kg \cdot m^2$
(b) the applied torque needed to accelerate it from rest to 1500 rpm in 5.00 s if it is known to slow down from 1500 rpm to rest in 55.0 s。    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
59#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A softball player swings a bat, accelerating it from rest to 3;sbc/bv9a( y 3mt7tf c $rev/s$ in a time of 0.20 s. Approximate the bat as a 2.2-kg uniform rod of length 0.95 m, and compute the torque the player applies to one end of it.    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
60#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A teenager pushes tangentially on a small hand-driven merry-go-round n7 ;s4(i+at5mph gsu0u2hsnaku)- 0 9qglhy j and is able to accelerate it from rest to a frequency of 15 rpm in 10.0 s. Assume the merry-go-round is a uniform disk of radius 2.5 m and has a mass of 760 kg, and twoq50u4ya suu2 ( jgna+ik-hs ghps)0hm9;lnt 7 children (each with a mass of 25 kg) sit opposite each other on the edge. Calculate the torque required to produce the acceleration, neglecting frictional torque. $\approx$   $m \cdot N$ What force is required at the edge?    N

参考答案:     查看本题详细解析

标记此题
61#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A centrifuge rotor rotating at 10,300 rpm is shut off and is eventually kclc*cjbzfk7(c)8x 3aj0b ,fbrought uniformly to rest by a frictional torque of 1.jfz38cc 7b b*,xka0( cc)lkjf 2 $m \cdot N$ If the mass of the rotor is 4.80 kg and it can be approximated as a solid cylinder of radius 0.0710 m, through how many revolutions will the rotor turn before coming to rest,    $rev$ how long will it take?    s

参考答案:     查看本题详细解析

标记此题
62#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The forearm in Fig. 8–45 accelera 6d3nsvs ,/8nqkm,qaztes a 3.6-kg ball at 7 $m/s^2$ by means of the triceps muscle, as shown. Calculate
(a) the torque needed,    $m \cdot N$
(b) the force that must be exerted by the triceps muscle. Ignore the mass of the arm.    N


参考答案:     查看本题详细解析

标记此题
63#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Assume that a 1.00-km;(rlg;rb*yxy olxg.a:p + (l g ball is thrown solely by the action of the forearm, which rotates about the elbow joint under the actionr(;+oa x:p ybrm;l ylggx (.*l of the triceps muscle, Fig. 8–45. The ball is accelerated uniformly from rest to 10 $m/s$ in 0.350 s, at which point it is released. Calculate
(a) the angular acceleration of the arm,    $rad/s^2$
(b) the force required of the triceps muscle. Assume that the forearm has a mass of 3.70 kg and rotates like a uniform rod about an axis at its end.    N



参考答案:     查看本题详细解析

标记此题
64#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A helicopter rotor bl3s a3 n1a tfwj:wtp1z6ade can be considered a long thin rod, as shown in Fig. 8–46t j1wfnpa: t36a3swz 1.
(a) If each of the three rotor helicopter blades is 3.75 m long and has a mass of 160 kg, calculate the moment of inertia of the three rotor blades about the axis of rotation.    $kg \cdot m^2$
(b) How much torque must the motor apply to bring the blades up to a speed of 5 $rev/s$ in 8.0 s?    $m \cdot N$


参考答案:     查看本题详细解析

标记此题
65#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
An Atwood’s machine consists oft0jht6 +bichz twe sq.h4k gl0zl2jz- , we-;6 two masses, $m_1$ and $m_2$ which are connected by a massless inelastic cord that passes over a pulley, Fig. 8–47. If the pulley has radius R and moment of inertia I about its axle, determine the acceleration of the masses $m_1$ and $m_2$ and compare to the situation in which the moment of inertia of the pulley is ignored. [Hint: The tensions $F_{T1}$ and $F_{T2}$ are not equal. We discussed this situation in Example 4–13, assuming for the pulley.]

参考答案:    

标记此题
66#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A hammer thrower accelerates the hammer from repi 7i 7op58wgpst within four full turns (revolutio7ppi875p gw oins) and releases it at a speed of 28 $m/s$ Assuming a uniform rate of increase in angular velocity and a horizontal circular path of radius 1.20 m, calculate
(a) the angular acceleration,    $rad/s^2$
(b) the (linear) tangential acceleration,    $m/s^2$
(c) the centripetal acceleration just before release,    $m/s^2$
(d) the net force being exerted on the hammer by the athlete just before release,    N
(e) the angle of this force with respect to the radius of the circular motion.    $^{\circ} $

参考答案:     查看本题详细解析

标记此题
67#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A centrifuge rotor has a moment o+tw8 2dwq) s7bvvh; 1o qvk s:stkqm00f inertia of $3.75 \times10^{-2 }$ $kg \cdot m^2$ How much energy is required to bring it from rest to 8250 rpm?    J

参考答案:     查看本题详细解析

标记此题
68#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An automobile engine develops a torque of 280 pl 77osi3 ;j-jf6u9szcsj2.pr jpc*f$m \cdot N$ at 3800 rpm. What is the power in watts and in horsepower?    W    hp

参考答案:     查看本题详细解析

标记此题
69#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bowling ball of mass 7.3 kg and radius 9.0 cmzs 5-foo/. ki1:g uggm rolls without slipping down a lane kzi/fo1.gs5:g u go-m at 3.3 $m/s$ Calculate its total kinetic energy.    J

参考答案:     查看本题详细解析

标记此题
70#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Estimate the kinetic energy of the Earth with respect to the Sun as t 5wa ch3te 4quz+z8k8ete+1+xry ) pythe sum of two term3)+py8wy1e tqkzute5 x eh ct4r+z+a8s,
(a) that due to its daily rotation about its axis,$KE_{daily}$=    $\times10^{29 }$ J
(b) that due to its yearly revolution about the Sun. $KE_{yearly}$+    $\times10^{33 }$ J [Assume the Earth is a uniform sphere with $6 \times10^{ 24}$ kg and $6.4 \times10^{6 }$ m and is $1.5 \times10^{8 }$ km from the Sun.]$KE_{daily}$ + $KE_{yearly}$ =    $ \times10^{33 }$ J

参考答案:     查看本题详细解析

标记此题
71#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A merry-go-round has a mass of 1640 kg and a radius of 7.50 m. How much ne9 2k3;gj6, avnzvjjc st work is required to accelerate it from rest to a rotatioc,; njj9a36vg2v sz kjn rate of 1.00 revolution per 8.00 s? Assume it is a solid cylinder.    J

参考答案:     查看本题详细解析

标记此题
72#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A sphere of radius 20.a (g (tdi8wnd e v.76ggxmxj290 cm and mass 1.80 kg starts from rest and rolls without slipping down a 30.0 g. xvei(7j(6gx2dg amt9dw n8$^{\circ} $ incline that is 10.0 m long.
(a) Calculate its translational and rotational speeds when it reaches the bottom. $v_{CM}$ =    $\omega$ =    $rad/s$
(b) What is the ratio of translational to rotational KE at the bottom?    Avoid putting in numbers until the end so you can answer:
(c) do your answers in (a) and (b) depend on the radius of the sphere or its mass?

参考答案:     查看本题详细解析

标记此题
73#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Two masses, $m_1$ = 18 kg and $m_2$ = 26.5 kg are connected by a rope that hangs over a pulley (as in Fig. 8–47). The pulley is a uniform cylinder of radius 0.260 m and mass 7.50 kg. Initially, is on the ground and $m_2$ rests 3.00 m above the ground. If the system is now released, use conservation of energy to determine the speed of $m_2$ just before it strikes the ground. Assume the pulley is frictionless.    $m/s$


参考答案:     查看本题详细解析

标记此题
74#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 2.30-m-long pole is balancr:x fq/vh1b 3onoy :u 2hnrdx-6((tpaed vertically on its tip. It starts to fall and its lower end does not slip. What fn(txh:q-/uy1 2abh (:6 onxrrvodp3will be the speed of the upper end of the pole just before it hits the ground? [Hint: Use conservation of energy.]    $m/s$

参考答案:     查看本题详细解析

标记此题
75#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  What is the angular momentum of a 0.21zo7qh.t;67+ry w4jwpu9jx opeop1 : e 0-kg ball rotating on the end of a thin string in a 6 j1w7.oopypeh; wjz: te4poqr 79+uxcircle of radius 1.10 m at an angular speed of 10.4 $rad/s$?    $kg \cdot m^2$

参考答案:     查看本题详细解析

标记此题
76#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) What is the angular momentum of a 2.8-kg uniform cylindrical grinding rs . zrn*(s/ui6u,tqdu,x0ze wheel of radius 18 cmuz,rd i.s /e uzt6q xus*(,0nr when rotating at 1500 rpm?    $kg \cdot m^2$
(b) How much torque is required to stop it in 6.0 s?    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
77#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A person stands, hands at his side, on a platform that is rotating cvadphz,x6bm+ )-tvbq2h, 1-cl x:xtat a rate of 1.3rev/s If he raises his arms to a horizontal position, Fig.,bh 1txa,)x- - 6px:+dqmlh 2vtccbvz 8–48, the speed of rotation decreases to 0.8 $rev/s$ (a) Why?
(b) By what factor has his moment of inertia changed?

参考答案:    

标记此题
78#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A diver (such as the one shown in Fig. 8–29) lov8k5ah y:p*onn3g7z+jt8 bcan reduce her moment of inertia by a factor of about 3.5 wh85j*7 38aonolz k +vt nbhp:gyen changing from the straight position to the tuck position. If she makes 2.0 rotations in 1.5 s when in the tuck position, what is her angular speed ($rev/s$) when in the straight position?   $rev/s$


参考答案:     查看本题详细解析

标记此题
79#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A figure skater can increase her spin rotation rahe v3mz .0o5kkte from an initial rate of 1.0 rev every 2.0 s to a fie.hok0vz5m3k nal rate of 3 $rev/s$ If her initial moment of inertia was 4.6 kg*$m^2$ what is her final moment of inertia? How does she physically accomplish this change?    $kg \cdot m^2$

参考答案:     查看本题详细解析

标记此题
80#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A potter’s wheel is rotating around a vertical axis through its center alaeo mdz2t7m-nk8 /l3o dg n)/t a frequency of 1.5rev/s The wheel can be considered a unifnn7 l ke3m//)md-g8od laot2 zorm disk of mass 5.0 kg and diameter 0.40 m. The potter then throws a 3.1-kg chunk of clay, approximately shaped as a flat disk of radius 8.0 cm, onto the center of the rotating wheel. What is the frequency of the wheel after the clay sticks to it?    $rev/s$

参考答案:     查看本题详细解析

标记此题
81#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) What is the angular momentum of a figure skater spa2 z()op5 psbjinning at 3.5 $rev/s$ with arms in close to her body, assuming her to be a uniform cylinder with a height of 1.5 m, a radius of 15 cm, and a mass of 55 kg?    $kg \cdot m^2$
(b) How much torque is required to slow her to a stop in 5.0 s, assuming she does not move her arms?    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
82#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Determine the angular momentum oflpg8law23q gnuyo 6pak:u.* 8 the Earth
(a) about its rotation axis (assume the Earth is a uniform sphere),    $\times 10^{33} \; kg \cdot m^2$

(b) in its orbit around the Sun (treat the Earth as a particle orbiting the Sun). The Earth has mass $6 \times 10^{24} \; kg$ and radius $6.4 \times 10^{6} \; m$ and is $1.5 \times 10^{8} \; km$ from the Sun.    $\times10^{40} \; kg \cdot m^2$

参考答案:     查看本题详细解析

标记此题
83#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A nonrotating cylindrical disk of moment of inertia I is dropp;*b7ql gck+b9jgsj;z ed onto an identical dz;b*lb9sjgj kqg+ 7;c isk rotating at angular speed $\omega$ Assuming no external torques, what is the final common angular speed of the two disks?
参考答案:    

标记此题
84#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A uniform disk turns at 2.4 mx 3r;8yu9glsum i3t1$rev/s$ around a frictionless spindle. A nonrotating rod, of the same mass as the disk and length equal to the disk’s diameter, is dropped onto the freely spinning disk, Fig. 8–49. They then both turn around the spindle with their centers superposed. What is the angular frequency in rev/s of the combination?    $rev/s$


参考答案:     查看本题详细解析

标记此题
85#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A person of mass 75 kg stands at the center of a rotating merry-go-round platfor0.552n 6e cdyeryezgim of radius 3.0 m and moment y0dn5ziye g.r52e e c6of inertia 920 $kg \cdot m^2$ The platform rotates without friction with angular velocity 2 $rad/s$ The person walks radially to the edge of the platform.
(a) Calculate the angular velocity when the person reaches the edge.    $rad/s$
(b) Calculate the rotational kinetic energy of the system of platform plus person before and after the person’s walk.$KE_i$ =    J $KE_f$ =    J

参考答案:     查看本题详细解析

标记此题
86#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 4.2-m-diameter merry-go-round is rotating freely with an angular xz +d3v3 ou1vnvelocity of 0.8 vx dv33+1zoun$rad/s$ Its total moment of inertia is 1760 $kg \cdot m^2$ Four people standing on the ground, each of mass 65 kg, suddenly step onto the edge of the merry-go-round. What is the angular velocity of the merry-go-round now?    $rad/s$ What if the people were on it initially and then jumped off in a radial direction (relative to the merry-go-round)?    $rad/s$

参考答案:     查看本题详细解析

标记此题
87#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Suppose our Sun eventually collapses il)qcbz3o )s*d1v3ywfs u ,.fbnto a white dwarf, losing about half its mass in the process, and winding up with a radius 1.0% of its exisq b)sz f1svldy3b*.3w ou,c)fting radius. Assuming the lost mass carries away no angular momentum, what would the Sun’s new rotation rate be?(round to the nearest integer)$\approx$    $rad/s$ (Take the Sun’s current period to be about 30 days.) What would be its final KE in terms of its initial KE of today?$KE_{f}$=    $KE_{i}$

参考答案:     查看本题详细解析

标记此题
88#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Hurricanes can involve winds in excess of 124.tdks *b y7yjrhgor.,n9o: w0 $km/h$ at the outer edge. Make a crude estimate of
(a) the energy,    $ \times10^{16 }$ J
(b) the angular momentum, of such a hurricane, approximating it as a rigidly rotating uniform cylinder of air (density 1.3 $kg \cdot m^2$) of radius 100 km and height 4.0 km.    $ \times10^{20 }$ $kg \cdot m^2$

参考答案:     查看本题详细解析

标记此题
89#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  An asteroid of mass y m9,8 f4 mad:fucwic1/d;duj$ 1.0\times10^{ 5}$ traveling at a speed of relative to the Earth, hits the Earth at the equator tangentially, and in the direction of Earth’s rotation. Use angular momentum to estimate the percent change in the angular speed of the Earth as a result of the collision.    $\times10^{-16 }$ %

参考答案:     查看本题详细解析

标记此题
90#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A person stands on a platform, initially at rest, thattfkjp 6/r- ay- can rotate freely without friction. The moment of inertia of the person plus the platfr/-6-f j kyaptorm is $I_P$ The person holds a spinning bicycle wheel with its axis horizontal. The wheel has moment of inertia $I_W$ and angular velocity $\omega_W$ What will be the angular velocity $\omega_W$ of the platform if the person moves the axis of the wheel so that it points (a) vertically upward, (b) at a 60º angle to the vertical, (c) vertically downward? (d) What will $\omega_P$ be if the person reaches up and stops the wheel in part (a)?
参考答案:    

标记此题
91#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Suppose a 55-kg person stands at 2o. v(lztns1bthe edge of a 6.5-m diameter merry-go-round turntable that is mounted on frictionless bearings anl.2nstzb1 v(o d has a moment of inertia of 1700 $kg \cdot m^2$ The turntable is at rest initially, but when the person begins running at a speed of 3.8 $m/s$ (with respect to the turntable) around its edge, the turntable begins to rotate in the opposite direction. Calculate the angular velocity of the turntable.    $rad/s$

参考答案:     查看本题详细解析

标记此题
92#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A large spool of rope rolls on the ground with the end of the rope lying on thrc2d wj6bi 4wky(,fl0 e top edge of the spool. A person grabs the end of the rope and walks a distance L, holding onto it, Fig. 8–50. The spool rolls behind the p6( dbjwci,0yw2fk r4l erson without slipping. What length of rope unwinds from the spool? How far does the spool’s center of mass move?
参考答案:    

标记此题
93#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The Moon orbits the Earth such that the same side always faces the0v -kf i je: /0uen q3hh(dgepl.*k9nf Earth. Determine the ratio of the Moon’s v.*ke03 kpif0uf:ejq-eln n hdh /g( 9spin angular momentum (about its own axis) to its orbital angular momentum. (In the latter case, treat the Moon as a particle orbiting the Earth.)    $\times10^{ -6}$

参考答案:     查看本题详细解析

标记此题
94#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A cyclist accelerates from re:3byk54bqxzpc4 b o w:st at a rate of 1 m/$s^2$ How fast will a point on the rim of the tire at the top be moving after 3.0 s? [Hint: At any moment, the lowest point on the tire is in contact with the ground and is at rest — see Fig. 8–51.]    $m/s$


参考答案:     查看本题详细解析

标记此题
95#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A 1.4-kg grindstone in the shape of a uniform cylinder of radius 0.20 x ,sncr8 6um5m q:h/pnm acquires a rotatip,: 856r qn n/cusmmxhonal rate of from rest over a 6.0-s interval at constant angular acceleration. Calculate the torque delivered by the motor.    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
96#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) A yo-yo is made of two solid cylindric yeemz7igv2z9 l;p), j.j5st ey 9f0npal disks, each of mass 0.050 kg and diameter 0.075 m, joined by a (concentric) thin solid cylindrical hub of mass 0.0050 kg and diameter 0.010 m. Use conservation of energy to calculate the linear speed of the yo-yo when it reaches the end of its 1.0-m-long string, if it n2;9. e)l mp7eyp,g0zv tiefzy5j 9 sjis released from rest.    $m/s$
(b) What fraction of its kinetic energy is rotational?    %

参考答案:     查看本题详细解析

标记此题
97#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  (a) For a bicycle, how is the angular speed of the rea c x.;e. 79mywmv /gm-jm;lhyor wheel ($\omega_R$) related to that of the pedals and front sprocket ($\omega_F$) Fig. 8–52? That is, derive a formula for ($\omega_R$)/($\omega_F$) Let $N_F$ and $N_R$ be the number of teeth on the front and rear sprockets, respectively. The teeth are spaced equally on all sprockets so that the chain meshes properly.
(b) Evaluate the ratio ($\omega_R$)/($\omega_F$) when the front and rear sprockets have 52 and 13 teeth, respectively,   
(c) when they have 42 and 28 teeth.   


参考答案:     查看本题详细解析

标记此题
98#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Suppose a star the size of our Sun, but with mass5g8w dam2 o1emvok;: ):-oihtbdep 2l 8.0 times as great, were rotating at a speed of 1.0 revolution every 12 days. If it were to undergo gravim2:o:blot2mgdov);dk8pe- 5e i1w hatational collapse to a neutron star of radius 11 km, losing three-quarters of its mass in the process, what would its rotation speed be? Assume that the star is a uniform sphere at all times, and that the lost mass carries off no angular momentum.    $\times10^{9 }$ $rev/day$

参考答案:     查看本题详细解析

标记此题
99#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  One possibility for a low-pollut- coa slknai,65eif,( ion automobile is for it to use energy stored in a -isef 6ka o n,c(5ial,heavy rotating flywheel. Suppose such a car has a total mass of 1400 kg, uses a uniform cylindrical flywheel of diameter 1.50 m and mass 240 kg, and should be able to travel 350 km without needing a flywheel “spinup.”
(a) Make reasonable assumptions (average frictional retarding force = 450N twenty acceleration periods from rest to equal uphill and downhill, and that energy can be put back into the flywheel as the car goes downhill), and show that the total energy needed to be stored in the flywheel is about $ 1.7\times10^{8 }$J.    $ \times10^{ 8}$ J
(b) What is the angular velocity of the flywheel when it has a full “energy charge”?    $rad/s$
(c) About how long would it take a 150-hp motor to give the flywheel a full energy charge before a trip? $\approx$    min

参考答案:     查看本题详细解析

标记此题
100#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Figure 8–53 illustrate(+s3hhvdt 7s3pqrge 3 s an $H_2O$ molecule. The O–H bond length is 0.96 nm and the H–O–H bonds make an angle of 104 $^{\circ} $. Calculate the moment of inertia for the $H_2O$ molecule about an axis passing through the center of the oxygen atom
(a) perpendicular to the plane of the molecule,    $\times10^{-45 }$ $kg \cdot m^2$
(b) in the plane of the molecule, bisecting the H–O–H bonds.    $ \times10^{-45 }$ $kg \cdot m^2$


参考答案:     查看本题详细解析

标记此题
101#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A hollow cylinder (hoop) is rolling on mu,or1 t g*5+rxxugkyqtd /kif65v74a horizontal surface at speed v=3.3 $m/s$ when it reaches a 15 $^{\circ} $ incline.
(a) How far up the incline will it go? $\approx$    m (round to one decimal place)
(b) How long will it be on the incline before it arrives back at the bottom?    s

参考答案:     查看本题详细解析

标记此题
102#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A uniform rod of mass M and length L can pivot freely (i.e., we ignore frictjp p 2+hwqk/3j0w69 orgdo so/ion) about a hinge attached to a wall, as in Fig. 8–54. The rod is held horizontally and then released. At the moment of release, d wd/kpoq/jp+ ooj2g 3shrw096etermine (a) the angular acceleration of the rod, and (b) the linear acceleration of the tip of the rod. Assume that the force of gravity acts at the center of mass of the rod, as shown. [Hint: See Fig. 8–21g.]

参考答案:    

标记此题
103#
 
问答题 ( 1.0 分) 切至整卷模式 搜藏此题  
A wheel of mass M has radius+on15i4hj tp y1 wr1yth:gs9td: tj2m R. It is standing vertically on the floor, and we want to exert a horizontal force F at its axle so that it will climb a step against which it rests (Fig. 8–55). The step h 5tt1h:1 2t 1yj4h+srmytgjndip :9owas height h, where h

参考答案:    

标记此题
104#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A bicyclist traveling with sp ;hmn+5mmaqc 2eed v=4.2m/s on a flat road is making a turn with a radius The forch2m +;am mq5nces acting on the cyclist and cycle are the normal force $\left(\mathbf{\vec{F}}_{\mathrm{N}}\right)$ and friction force $\left(\mathbf{\vec{F}}_{\mathbf{fr}}\right)$ exerted by the road on the tires, and $m\vec{\mathbf{g}}$ the total weight of the cyclist and cycle (see Fig. 8–56).
(a) Explain carefully why the angle $\theta$ the bicycle makes with the vertical (Fig. 8–56) must be given by tan $\tan\theta=F_{\mathrm{fr}}/F_{\mathrm{N}}$ if the cyclist is to maintain balance.(round to the nearest integer)
(b) Calculate $\theta$ for the values given.    $^{\circ} $
(c) If the coefficient of static friction between tires and road is $\mu_s=0.70$ what is the minimum turning radius?    m



参考答案:     查看本题详细解析

标记此题
105#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Suppose David puts a 0.50-kg rock into a sling of lenkirg m* mk*u1 *f:)kilgth 1.5 m and begins whirling the rock in a nearly horizontal circle *l*ui mk*f k):mgr1ik above his head, accelerating it from rest to a rate of 120 rpm after 5.0 s. What is the torque required to achieve this feat, and where does the torque come from?    $m \cdot N$

参考答案:     查看本题详细解析

标记此题
106#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Model a figure skater’s body as a solid cyl vk)7e-sgx u/ pxv4so:inder and her arms as thin rods, making reasonable estimates for the dimensions. Then calculate the ratio of the angular speeds for a spinning skater with outstretched arms, and with arms held tightly against ks vgxse7vu: 4/xp )o-her body.   

参考答案:     查看本题详细解析

标记此题
107#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  You are designing a clutch assembly which consists of two cynid+ie h338cft)bf j* lindrical plates, of mass d cfe)fnji 3+ti8h 3b*$M_{\mathrm{A}}=6.0$ $\mathrm{kg}$ and $M_{\mathrm{B}}=9.0$ $\mathrm{kg}$ with equal radii R=0.60 $\mathrm{m}$ They are initially separated (Fig. 8–57). Plate $M_{\mathrm{A}}$ is accelerated from rest to an angular velocity $\omega_1=7.2$ $\mathrm{rad/s}$ in time $\Delta t=2.0$ s Calculate
(a) the angular momentum of $M_{\mathrm{A}}$    $kg \cdot m^2$
(b) the torque required to have accelerated $M_{\mathrm{A}}$ from rest to $\omega_{1}$    $m \cdot N$
(c) Plate $M_{\mathrm{B}}$ initially at rest but free to rotate without friction, is allowed to fall vertically (or pushed by a spring), so it is in firm contact with plate $M_{\mathrm{A}}$ (their contact surfaces are high-friction). Before contact, $M_{\mathrm{A}}$ was rotating at constant $\omega_{1}$ After contact, at what constant angular velocity $\omega_{s}$ do the two plates rotate?    $rad/s$


参考答案:     查看本题详细解析

标记此题
108#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  A marble of mass m and radius r rolls along t0jqsw5 2rc5z phe looped rough track of Fig. 8–58. What is the minimum value oqws 5025cp jzrf the vertical height h that the marble must drop if it is to reach the highest point of the loop without leaving the track? Assume $r\ll R$ and ignore frictional losses. h =    R



参考答案:     查看本题详细解析

标记此题
109#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  Repeat Problem 84, but do not a fx/,hx q 1s.9dm(ce ysc(bul8ssume $r\ll R$ h =    (R-r)

参考答案:     查看本题详细解析

标记此题
110#
 
填空题 ( 1.0 分) 切至整卷模式 搜藏此题  
  The tires of a car make 85 revolutions as the car red xiacl ju xa9d4m:.)zfv+9z-t uces its speed uniformly from 90km/h to 60km/h The tires have a diameter of 0.90 m. (a) What was the angular acceleration of e:za4i utdljx)9+-z .cxm9 favach tire? $\approx$    $rad/s^2$(round to two decimal place)
(b) If the car continues to decelerate at this rate, how much more time is required for it to stop?    s

参考答案:     查看本题详细解析

  • :
  • 总分:110分 及格:66分 时间:不限时
    未答题: 已答题:0 答错题:
    当前第 题,此次习题练习共有 110 道题
    本系统支持习题练习,作业与考试三大模式,作业考试自动评分,成绩排序一键导出,可设定动态变量同一试卷千人千题
    如果您对本系统感兴趣,想加入我们或者想进行任何形式的合作,请加微信 skysky1258

    浏览记录|使用帮助|手机版|切到手机版|题库网 (https://tiku.one)

    GMT+8, 2025-1-18 15:35 , Processed in 0.267446 second(s), 241 queries , Redis On.