A river 800 m wide flows at 5 km/hr . a swimmer , velocity 10 km/hr wishes to cross the river straight. along what direction must he strike?what should be the resultant velocity?how much time will he take?
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Let the river flow from North to south. Swimmer wants to cross from West to East.
Then swimmer swims along x degrees. North of East to cross the river straight.
Then: Tan x = 5 / 10 = 1/2 so angle = arctan 1/2
resultant speed = sqrt(10^2 - 5^2) = 5 √3 km/hr
time = 0.800 / 5√3 hours = 3.2 * √3 minutes
Then swimmer swims along x degrees. North of East to cross the river straight.
Then: Tan x = 5 / 10 = 1/2 so angle = arctan 1/2
resultant speed = sqrt(10^2 - 5^2) = 5 √3 km/hr
time = 0.800 / 5√3 hours = 3.2 * √3 minutes
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