Question #e7a66

1 Answer
Feb 27, 2017

Answer:

The length is #=1m#

Explanation:

The period of a simple pendulum is

#T=2pisqrt(L/g)#

Period #=Ts#

Length #=L (m)#

Therefore,

#L/g=T/(4pi^2)#

In the first case, we have

#L=(Tg)/(4pi^2)=(4^2*9.8)/(4pi^2)=4m#

In the second case,

#T=60/30=2s#

So,

#L=(4*9.8)/(4pi^2)=1m#