Question

An object with mass 0.220 kg is acted on by an elastic restoring force with force constant 10.5 N/m. The object is set into oscillation with an initial potential energy of 0.150 J and an initial kinetic energy of 5.60×10−2 J.

From the problem (a), (b), and (c) I got

Amplitude 0.198m

Potential energy when the displacement was at half 5.15*10^-2 J

Displacement when Potential energy and Kinetic energies are equal 0.140m

And I don't know

(d) What is the value of the phase angle ϕ if the initial velocity is positive and the initial displacement is negative?

Now I got 2.356 rad for the (d) but I can't sure

Answer 1