Answer:
4L
Explanation:
mass of pendulum = M, length of pendulum, L1 = L,
acceleration due to gravity = g, Amplitude = A
Use the formula for the time period for simple pendulum
[tex]T = 2\pi \sqrt{\frac{L}{g}}[/tex] ..... (11)
Let the new length be L2 for which the time period is 2T.
[tex]2T = 2\pi \sqrt{\frac{L_{2}}{g}}[/tex] ..... (2)
Divide equation (2) by equation (1)
[tex]\frac{2T}{T} = \sqrt{\frac{L_{2}}{L}}[/tex]
So, L2 = 4 L
Thus, the length of the pendulum is 4 L.