I just can't seem to see what to do, and it is very frustrating because I know it's relatively easy 
anyway, the question is: "The period of a particle moving in SHM is 6s and its amplitude is 8cm. Calculate its velocity and acceleration (to 1dp) when the displacement is 5cm from the centre of motion."
i know i need to use v^2=n^2(a^2-x^2) and i also need to use acceleration = -n^2x, but i am struggling. someone please help?
anyway, the question is: "The period of a particle moving in SHM is 6s and its amplitude is 8cm. Calculate its velocity and acceleration (to 1dp) when the displacement is 5cm from the centre of motion."
i know i need to use v^2=n^2(a^2-x^2) and i also need to use acceleration = -n^2x, but i am struggling. someone please help?