The formula for displacement in simple harmonic motion is:
x = A sin (ωt)
The derivative would therefore give speed:
x' = Aωcos (ωt)
The maximum speed is when cos(ωt) is at the maximum or 1. So max speed is:
v(max) = Aω
36cm/s = A ((40 oscillations/minute) * (1 minute/second) * (2π/1 oscillation))
A = 36cm s-1 / 4.188s-1
Amplitude A = 8.59 cm.
