physics
posted by Jessica .
A 200g mass attached to a horizontal spring oscillates at a frequency of 2.0 Hz. At one instant, the mass is at x= 5.0cm and has v= 30cm/s.
find amplitude

First get the spring constant, k, from the frequency f and the mass m.
2 pi f = sqrt(k/m)
k = m (2 pi f)^2 = 31.6 N/m
You can get the total energy from
Etotal = (1/2)mV^2 + (1/2)kX^2
= (1/2)*0.2*(0.3)^2 + (1/2)*31.6*(.05)^2
= 0.009 + 0.0395 = 0.0485 J
Get the amplitude Xmax from the total energy by setting V = 0