Question

pls solve it.. a pendulum complete two oscillations in 5 seconds .its time period is 2.5 seconds. if g is equal to 9. 8 ms - 2 find its length​

Answer 1

just apply formula of time period i.e
T=2pi root of l/g

Answer 2

T=2π√l/g

T²= 4π²(l/g)

l =(T²×g)/4π²

g=9.8 m/s²

l = (2.5²×9.8)/4×π²

= 3001.25/1936

=1.55m