Suppose a man swims 5km/h in calm water. If he swims tpwards east in a wide stream with a north west current of 3km/hr . What is the resultant velocity
Answers
Answer:
Secondary SchoolPhysics 5+3 pts
man can swim at the rate of 5km/hr in still water. a river 1km wide flows at the rate of 3km/hr. a swimmer wishes to cross the river straight.Along what direction must he strike. what should be his resultant velocity. how much time he would take to cross.
Report by Rahulpathak18 28.05.2017
Answers
Bhadauriayashraj098 · Ambitious
Know the answer? Add it here!
Kalpeshprabhakar
Kalpeshprabhakar Maths AryaBhatta
Hey there !
Solution:
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 = 5²
=> x² = 5² - 3²
=> x² = 25 - 9
=> x² = 16
=> x = √16 = 4 m/s
Hence the swimmer would go at a velocity of 4 m/s in a perpendicular path from the other bank.
So the question also inquires for time.
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 / 4 m/s
=> Time = 250 seconds or 4 minutes and 10 seconds.
Hope my answer helped !
Refer to the attachment for diagram !
In the diagram,
Vm = Velocity of man
Vr = Velocity of river
V = Resultant Velocity