Time dilation

[mntb]

For a disk that rotates with angular speed w, there is a clock at the center(at rest), adn one at distance r, with speed rw,. I need to show that frome time dilation in special relativity, time inervals (△ t) for the clock at rest, and (△ t') for the moving clock are related by
(△ t'-△ t)/(delta t) ~ r²w²/2c²

I got a minus sign in front, by using the time dilation.

 

[HallsofIvy]

I don't see what the difficulty is? You know the formula for time dilation using linear speed v, don't you?
You say that the speed is rω. Plug that into the formula.