Answer is Incorrect:

On dimensional ground, the relation is tan = v

Dimension of R.H.S = M^{0} L^{1} T^{–1}

Dimension of L.H.S = M^{0} L^{0} T^{0}

( The trigonometric function is considered to be a dimensionless quantity)

Dimension of R.H.S is not equal to the dimension of L.H.S. Hence, the given relation is not correct dimensionally.

To make the given relation correct, the R.H.S should also be dimensionless. One way to achieve this is by dividing the R.H.S by the speed of rainfall v'.

Therefore, the relation reduces to tan θ= v/v_{1}

This relation is dimensionally correct