A simple pendulum

Question

A pendulum  of length 1m  is released  from theta =60 degree . The rate of change of speed  of the bob at  theta = 30 degree is

Answer 1

We know that Rate change of speed, dv/dt= tangential acceleration =tangential force/mass

When θ=30^∘, tangential force is mgsinθ

Therefore F=mgsin30

ma=mgsin30

 a=mgsin30/m

=10sin30

=10×1/2

=5m/s²

So, The rate of change of speed  of the bob at  theta = 30 degree is 5m/s²