A wedge is placed on a smooth horizontal plain and a rat runs on its sloping side. The velocity of the wedge is `v=4ms^(-1)` towards the right. What should be the velocity of the rat with respect to the wedge `(u)`, so that the rat appears to ,move in the vertical direction to an observer stading on the ground?

Options

A. `2 m//s`
B. `4 m//s`
C. `8 m//s`
D. `4sqrt(2) m//s`

Answer

c

Explanation

`vecv_(r)=vecv_(rw)+vecv_(w)`
`v/u=cos theta`
`implies u =v/(cos theta)=4/(cos 60^(@))=8 m//s`