Question

A pendulum completes 2 oscillation in 5s
a. what is it's time period?
b. If g=9.8 m/s
Find it's lengths​

Answer 1

2 oscillations in 5 s hence 1 oscillation in 2.5 s which is its time period

T=2π√1/g

2.5=2π√1/g

1=10×6.25/4π²=1.58m

Answer 2

Explanation:

2 oscillations in 5 s hence 1 oscillation in 2.5 s which is its time period

T=2π √l/g

2.5= 2π √l/g

l=10×6.25/ 4π

=1.58m