Here's the question you clicked on:
hawkfalcon
A particle moves in the xy-plane so that at any time t its coordinates are x = α cos βt and y = α sin β t , where α and β are constants. The y-component of the acceleration of the particle at any time t is
well the second derivative of the position function is the acceleration function
so you need to find y ''
So find the second derivative of the y equation?