Question

A man who can swim at the rate of 2 km/hr (in still river) crosses a river to a point exactly opposite on
the other bank by swimming in a direction of 120° to the flow of the water in the river. The velocity of the
water current in km/hr is
(1) 1
(2) 2
(3) 1/2
(4) 312​

Answer 1

Answer:

V

m

= Velocity of man,

V

r

= Velocity of rain,

V

mr

=V

m

−V

r

Taking components,

V

mr

cos120

∘

=V

m

cos90

∘

−V

r

cos0

∘

2×(−

2

1

)=−V

r

So,V

r

=1km/hr