Chapter 7 ) A grindstone increases in angular speed from 4 rad\'s to 12 rad/sin

Question

Chapter 7 ) A grindstone increases in angular speed from 4 rad's to 12 rad/sin 4 seconds. Thr Through what angle does it turn during that time if the angular acceleration is constant? ANS: 32 rads 2) A potter's wheel moves uniformly from rest to an angular speed of 1 rev/s in 30 seconds. (a) Find its angular acceleration in radians per second per second. (b) Find its angular displacement in radians. ANS: (a) 0.21 rad/s; (b) 94.2-94.5 rads 3) A denti min. (a) Find the drils angular speed in radians/sec. (b) Find the drill's angular acceleration. (c) Determine the angle (in radians) through which the drill rotates during this period. st's drill starts from rest. After 3.2 seconds of constant angular acceleration it turns at a rate of 2.51x10 rev/ ANS: 2,628.5 rad/s; (b) 821.4 rad/s; (c) 4,205.5-4,205.6 rads

Explanation / Answer

1. w1 = 4 rad/s

w2 = 12 rad/s

t = 4 s

let the angle be theta

then

2*alpha*theta = w2^2 - w1^2

also

w2 = w1 + alpha*t

12 = 4 + alpha*4

alpha = 2 rad/s/s

hence

2*2*theta = 144 - 16

theta = 32 radians

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