A girl in a swing is 2.5 m above ground at the maximum height and at 1.5 m above the ground at the lowest point. Her maximum velocity in the swing is `(g=10ms^(-2))`

Options

A. `5sqrt(2)ms^(-1)`
B. `2sqrt(5)ms^(-1)`
C. `2sqrt(3)ms^(-1)`
D. `3sqrt(2)ms^(-1)`

Answer

B

Explanation

In this case,
Change in potential energy = Kinetic energy
`(1)/(2)mv^(2)=mg(h_(2)-h_(1))`
`v^(2)=2g(2.5-1.5)`
`v^(2)=2xx10xx1`
`v=sqrt(5xx2xx2)`
`v=2sqrt(5)m//s`
`v=2sqrt(5)m//s`