# Thread: Simple Harmonic Motion (F=-kx) --- Help!

Q: The formula for Hooke's LAW is Felastic=-kx , so, the "X" is always negative? And the "F" is always negative? I know the "K" is always should be positive but please explain to me because I'm confused which to put negative and which to put positive; I wanna understand!

A: ?

I'm waiting for an answer as soon as possible!
Thank You!

2. Originally Posted by Nation-of-Progress

Q: The formula for Hooke's LAW is Felastic=-kx , so, the "X" is always negative? And the "F" is always negative? I know the "K" is always should be positive but please explain to me because I'm confused which to put negative and which to put positive; I wanna understand!

A: ?

I'm waiting for an answer as soon as possible!
Thank You!
Actually, x may be either positive or negative. When x is negative, F is positive (pointing to the right), and when x is positive, F is negative (pointing toward the left). What that means is that the force is always pullling the mass back toward x=0. Be sure to draw a diagram for each of the cases so that you get a mental picture of what is going on. It wouldn't hurt to hand a mass on a spring and feel the force for various positions either.