# Homework Help: Angular speed and linear speed

1. Oct 10, 2011

### imy786

1. The problem statement, all variables and given/known data

a ball moves at 5000 rpm (revolutions per minute). Their radius is 4 cm.

(i)Determine the angular speed in radians per second.

(ii) Find the period of rotation

(iii) Find the linear speed of a point on the outer ball

(iv) Find the linear acceleration of a point on the outer edge of the ball.

2. Relevant equations

angular speed = 2∏ / T

3. The attempt at a solution

(i)

r = 4cm = 0.04m
circumference = 2∏r = 0.08∏

1 rev = 2∏°
5000 rev/min = 5000 X 2∏° / min
10,000∏° / min
10,000∏° / min = 10,000∏° per 60 secs

10,000∏° / 60 = 166.67∏°/sec

angular speed = 166.67∏°/sec

is this correct for part (i)

Last edited: Oct 10, 2011
2. Oct 10, 2011

### Spinnor

3. Oct 10, 2011

### lightgrav

1 rev = 2∏ radians = 360° ; be careful with your units.
You might as well say that omega = 523.6 rad/sec.

4. Nov 17, 2011

### imy786

Find the period of rotation

T = 2 ∏ / omega = 2∏/523.6 = 0.012 seconds

5. Nov 18, 2011

### imy786

is this correct?

6. Nov 19, 2011

### imy786

why isnt anyone responding?