Amplitude does not affect period if the oscillations are small (less than about 30 degrees).
If the approximation theta = sin theta is made, the period becomes
P = 2 pi sqrt(L/g)
What happens if you double L?
Period is sqrt2 times larger.
I don't think they expect you to know the exact formula for the period of a pendulum for large angle osciallations. It requires an infinite series. If you need to know it, and how to derive it, I can give you a reference.
AHHHHHH Help!! Mass on string of unknown length oscillates witha period of 6.0s What if string length is doubled? amplitude dbl?
1 answer
1 answer