The length of a simple pendulum is increased by 44%. What is the percentage increase in its period ?

For a simple pendulum ∝T2 or l=CT2where C is a constant .Originally let / = 100cm, then 100 CT2When the length is increased by 44%, let the time is increased by t. Then144=C(T+t)2…(2)From eqs. (r) and (2)144100=(T+t)2T2  or  T+tT=1210=65 tT=65−1=15 Percentage increase  tT×100=15×100=20%