A man swims from a point `A` on the bank of a river if width `100 m`. When he swims perpendicular to the water current, he reaches the other bank `50 m` downstream. The angle to the bank at which he should swim, to reach the directly opposite point `B` on the other bank is.
.

Options

A. `10^@` upstream
B. `20^@` upstream
C. `30^@` upstream
D. `60^@` upstream

Answer

D

Explanation

(d) Refer to (Fig. S5.68) (a),
`tan theta = (v_w)/(v_m) = (50)/(100) = (1)/(2) or v_m = 2v_w`
Refer to (Fig .S5.68) (b),
`sin prop = (v_w)/(v_m) = (v_w)/(2 v_w) = (1)/(2)`
or `theta = 30^@`
So, it is `60^@` upstream.
(a) ,