# Simple Harmonic Motion and Springs

Doc Al
Mentor
i could get the period from either 1/f or 2pi/omega...
Well, yeah. But I meant the other formula. (From post #1.)

T=2pi/sqrt(m/k) ?

Doc Al
Mentor
T=2pi/sqrt(m/k) ?
Yes, that's the one. If you knew m/k, then you can calculate the period. Use energy conservation to figure out m/k.

thats what ive been trying to do, but im not sure what way to find m/k
one way is to use the equilibrium displacment equation, y = mg/k, but i didnt get the right answer from there

Doc Al
Mentor
one way is to use the equilibrium displacment equation, y = mg/k, but i didnt get the right answer from there
That's certainly one way to solve for m/k. But what would you use for y? Where is the equilibrium position.

Conservation of mechanical energy is another way to solve for m/k. Both methods give the same answer, of course.

i dont im confusing myself, i will try mechanical energy.

but wait, for mechanical energy equations wouldnt i need m, v, or k...so im utterly confused, can i ask you a favor of working the problem out so i can see what you mean?

Doc Al
Mentor
but wait, for mechanical energy equations wouldnt i need m, v, or k...so im utterly confused, can i ask you a favor of working the problem out so i can see what you mean?
Mechanical energy will involve m, v, and k. But that's good since that's what we're trying to find. (Remember that we want m/k so we can find the period.)

Set up an energy equation:
Energy(at top of motion) = Energy(at lowest point of motion).