What is the tangential acceleration of a point on a rotating crankshaft?

[goober19]

Homework Statement

A 3.0-cm diameter crankshaft that is initially rotating at 2500 rpm comes to a halt in 1.5 s. What is the tangential acceleration of a point on the surface of the crankshaft? How many revolutions does the crankshaft make as it comes to a stop?

Homework Equations

at = Dv/Dt

The Attempt at a Solution

honestly I am really stuck on this because the only formula that I can find is this one. Any ideas on where to head with it?

 

[Spinnor]

For linear motion we have,

v = v_o + a*t

For rotational motion we have,

thetadot = thetadot_o + thetadoubledot*t

thetadot = d theta/dt thetadoubledot = d^2 theta/dt^2

You know thetadot at t = o and you know thetadot at t = 1.5 seconds, solve for thetadoubledot