A bridge is the form of a semi-circle of radius 40 m. The greatest speed with which a motor cycle can cross the bridge without leaving the ground at the highest point is (g = 10 `ms^(-2)`)
(Frictional at force is negligibly small)

Options

A. 40 `ms^(-1)`
B. 20 `ms^(-1)`
C. 30 `ms^(-1)`
D. 15 `ms^(-1)`

Answer

B

Explanation

Given r = 40 m and g = 10 `ms^(-2)`
We have `v = sqrt(gr)`
`= sqrt(10 xx 40)`
`= sqrt(400)`
`= 20 ms^(-1)`