# A pendulum is executing simple harmoinic motion with a time period T if the length of pendulum is decreased to 36% the percentage chage in the time period of the pendulum is 1)60%2)40%3)10%4)20%

Arun
25758 Points
4 years ago
By formula $T_{1}=2\pi \sqrt{\frac{l}{g}}$\

now length is decreased by 21% therefore new length = L – 36L/100 = 64 L/100          put in eq we get
T2 = 2$\pi$$\sqrt$36L/100 = T1 * 6/10

T1 - T2 = 0.4 T1
so percentage change = $\frac{change in time period }{original time period}\times 100$   = 0.4*100   = 40%