# The simple pendulum

1. Homework Statement
Hey guys, I am reading my Physics book, in that specific section it says "the restoring force must be directly proportional to x or (because x=(theta)*L) to theta"

## The Attempt at a Solution

I have tried to look for that x=(theta)*L relationship online; however, I was not able to find it. I was hoping someone here could explain that relationship to me.
Thank you.

Last edited by a moderator:

Related Introductory Physics Homework Help News on Phys.org
mfb
Mentor
Did you draw a force diagram? It should become clear from that.

Yeah it comes with a diagram, but i do not see how multiplying L by the displaced angle, I can end up with the length of the arc. Like, how the unit conversion works. for that? With the diagram I can see where the the restoring force in the pendulum comes from though.

mfb
Mentor
The arc length is L*theta by definition of the arc length or the angle.
For small angles, this is approximately equal to the horizontal displacement as well.

And how would the unit conversion work that by doing the equation, it provides the arc length?

haruspex