Find its displacement?

Question

An object stretches a spring 5 cm in equilibrium. It is initially displaced 10 cm above equilibrium and given an upward velocity of 0.25 m/s. Find its displacement for t>0. Find the frequency, period, amplitude, and phase angle of the motion.

 

y"+(k/m)y=0

k/m=g/delta l=32/5 cm=6.4

y"+6.4y=0

But up to this point, am I right?

Answer 1

Dear Yang,  So far you are wrong because your units are wrong. I assume the spring is stretched by gravity.

 

k/m = omega^2 = g/delta x = (9.8 m/s^2)/(0.05m) = 196 1/s^2

 

Charles