A pendulum bob has a speed 3m/s while passing through its lowest position. What is its speed (in m/s) when it makes an angle of `60^0` with the vertical? The length of the pendulum is 0.5m Take `g=10 m/s^2`.

Answer

2

Explanation

`(1)/(2) mv^(2) + mgl (1 - cos theta) = (1)/(2) mv'^(2)`
or `v^(2) + 2gl (1 - cos theta) = v^(2)`
or `v^(2) + 2 xx 10 xx 0.5 (1 - (1)/(2)) = 9`
or `v^(2) = 9 - 5 = 4`
or `v = 2 ms^(-1)`.