Question

Q.5 The relative velocity of a swimmer with respect to earth is 15km/hr when swimming with the stream and 5km/hr when swimming against the stream Find the (i) velocity of water current , (ii) velocity of swimmer in still water​

Answer 1

Given

v (with stream) = 15 km/h

v (without stream) = 5 km/h

To find

Velocity of stream

and, velocity of swimmer in still water

Solution

Let the velocity of water be x

and let the velocity of the stream be y.

So, x + y = 15 (with stream) - i)

and x -  y = 5 (without stream)  - ii)

adding i) and ii) we get,

x + y + x - y = 15 + 5

2x = 20

x = 20/2

x = 10

So, the velocity of water current = x = 10 km/h

From i) we get that y = 15 - x

y = 15 - 5

y = 10 km/h

Velocity of swimmer = y = 10km/h