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 = 10 ms^(-2))

A girl in a swing is 2.5 m above ground at the maximum height and at 1

1.	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 = 10 ms^(-2))
Answer» `5sqrt(2) ms^(-1)` `2sqrt(5) ms^(-1)` `2sqrt(3) ms^(-1)` `3sqrt(2) ms^(-1)` Solution :At the highest point, `V = 0, h_1 = 2.5 m` `:.` Total energy `, E_1 = mgh_1 + 0 = mgh_1` At the lowest point, `v = ?, h_2 = 1.5 m` `:. ` Total energy , `E_2 = mgh_2 + 1/2 mv^2` According to the law of CONSERVATION of MECHANICAL energy `E_1 = E_2` `:. mgh_1 = 1/2 mv^2 + mgh_2 " or " v^2 = 2g (h_1 - h_2)` Or `v = sqrt(2h(h_1 - h_2)) = sqrt(2 XX 10 xx (2.5 - 1.5)) = 2sqrt(5) ms^(-1)`.