A body is suspened?

Question

A body is suspended vertically from an ideal spring of spring constant 2.5 n/m. the spring is intialily in its relaxed position. the body is then released and oscillates about it equilibrium position. the motion is described by y=(4.0cm)sin{(0.70rad/s)f}

what is the maximum kinetic energy of the body?

Answer 1

Your equation gives you the displacement of the body, so take the derivative of the equation to get the velocity. The derivative will have a cosine function in it. The maximum velocity will be when the cosine function has a value of 1 ( or -1). Use this maximum velocity to compute the kinetic energy of the body. You will need the mass of the body to compute the kinetic energy also. If you are not given the mass then you are expected to figure it out from the spring constant and displacement.