Question
A river 100 m wide is running downwards at the rate of 1 km per hour and a swimmer who can swim at the rate of 3·6 km/hr wishes to reach a point just opposite. Along which direction should he strike and how long will he take to cross the river?
Solution
Given,
Width of the river = 100 m
Rate of flow of river = 1 km/hr
Rate of flow of swimmer = 3.6 km/hr
Let the swimmer dive at an angle
as shown in figure to reach the point B directly opposite to A.
From the fig., we have
∴
Therefore, the swimmer should dive at angle (90 + 16·14) =106·14° with the direction of flow.
Width of the river = 100 m
Rate of flow of river = 1 km/hr
Rate of flow of swimmer = 3.6 km/hr
Let the swimmer dive at an angle
as shown in figure to reach the point B directly opposite to A. From the fig., we have
∴
Therefore, the swimmer should dive at angle (90 + 16·14) =106·14° with the direction of flow.
Now,
Time taken to cross the river, t =
Time taken to cross the river, t =
