A jet water, whose cros section is 'a' strikes a wall making an angle `theta` with normal and elastically rebounds. The velocity of water of density 'd' is v. Force exerted on wall is :-

Options

A. `2A upsilon rho cos theta`
B. `2A upsilon^2 rho cos theta`
C. `2A upsilon^2 rho `
D. `12A upsilon rho `

Answer

B

Explanation

Change in momentum = Impulse
[by impulse momentum theorem]
`implies 2 mv cos theta = F xx t`
`implies F = (2mv cos theta)/t = (2V rhov cos theta)/t`
`implies F= 2Arhov^2 cos theta " " [{:("As " V = Al),(l//t=v):}]`