# Angular displacement

1. Mar 5, 2006

### alex_boothby

hi,

how do i work out the angular displacement of ball bearing 0.00765 m in radius over 0.05 meters?

i need it to work out angular speed.

thank you

2. Mar 5, 2006

### Staff: Mentor

Perhaps you need:

$$d = \theta r$$

$$v = \omega r$$

Where the angle is measured in radians.

3. Mar 5, 2006

### alex_boothby

im doing this piece of work about a ball bearing rolling down an invlined slope and translational kinetic energy + rotational kinetic energy should = potential enegry.

but im not sure how to work out rotational kinetic energy. im not sure of the equations you just gave me, sorry, a little more help maybe?

can i not just say that the angular displacement is 0.05 meters? as that is how much we moved the ball bearing back each time?

thank you, but could i please have a little more help?