r = radius
α = angular acceleration
t = time
w₀ = initial angular velocity = 0 rad/s
w(t) = angular velocity at any time "t"
Angular velocity at any time is given as
w(t) = w₀ + α t
w(t) = α t since w₀ = 0
w(t) = α t eq-1
centripetal acceleration at any time is given as
a(t) = r w²(t)
using eq-1
a(t) = r (α t)²
a(t) = r α² t²