What is the arc length of a pendulum bob with mass m and length l?

[william kat]

a pendulum bob of mass m hangs on a string of length l. what is the espression for the arc length of the bob if its discplaced through an angle theta.

 

[Mu naught]

well if you know the maximum angle of displacement the arc length is simply

theta*l

 

[william kat]

problem is, the angle of discplacement is not known. its part of the expression