Shaft Angular velocity question

[andycampbell1]

Hi
Doing some revising for my exams with past papers. I just need some help to begin this question.

Q
The shaft of diameter 0.25 is rotating at 3000 rev/min Determine
a) The angular velocity
b) The linear speed of a point on the circumference of the shaft
c) The angular acceleration required to increase the shaft speed to 5000 rev/min in a period of 90 seconds
d) The linear acceleration of a point on the circumference of the shaft.

Homework Equations

$$\omega$$₂=$$\omega$$₁+$$\alpha$$t.


$$\theta$$=$$\omega$$1t+1/2 $$\alpha$$t².

$$\omega$$₂²=$$\omega$$₁²+ 2$$\alpha$$$$\theta$$

$$\theta$$=S/R

$$\omega$$=V/r

$$\alpha$$=a/r

I have converted the revs per mins to rad/s² using 2pi(3000)/60 and attained the answer 314.2 rad/s² for question (a) and for question (c) I have calculated the angular acceleration as 2.33 rad/s. I done this by converting 5000 rpm to rad/s which gave me 523.6 rad/s. To calculate the angular acceleration I subtracted the original velocity 314.2 from 523.6 rad/s and got the answer 209.4 which I divided by 90s which gave me 2.33. I would like help on how to begin question b, I have no idea how to start this question.

 

[edgepflow]

Remember, your units of angular velocity are rad/s (not rad/s^2).

For part (b), try the 5th equation you listed.