a man can swim at the rate of 6kmph in still water. A river 1km wide flows at the rate of 3kmph then find the how much time he would take to cross river is
Answers
Answer:
192.67 seconds
Explanation:
Since the man needs to swim straight towards the bank, we can say that the vector must be perpendicular to the bank.
So the speed of the stream is 3 km/hr and the person has to go straight towards the bank. Hence the person must be swimming diagonally to make a straight path.
So if we imagine the thing to be right angle triangle, the hypotenuse would be the swimmer's direction and the base would be the river's velocity and direction.
So Applying Pythagoras Theorem we get,
3² + x² = 6²
=> x² = 6² - 3²
=> x² = 36 - 9
=> x² = 27
=> x = √27 = 5.19 m/s
Hence the swimmer would go at a velocity of 5.19 m/s in a perpendicular path from the other bank.
We know that, Time = Distance / Speed
=> Distance = 1 km = 1000 m
Distance is converted to meters as the speed is in meter per second.
=> Time = 1000 m / 5.19 m/s
=> Time = 192.67 seconds
Hope it helps you
Answer:
Above answer is perfect