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.
Answers
Answered by
12
please mark brainliest
Attachments:
Answered by
3
Answer:
Explanation:
A.Velocity of man with respect to river water, `v = 5 km h^-1`. This is greater than the river flow velocity. Therefore, he can cross the river directly (along the shortest path or no drift condition from flow velocity). The angle of swim,
`theta = (pi)/(2) + sin^-1 ((u)/(v))`
=`90^@ + sin^-1 ((u)/(v))`
=`90^@ + sin^-1 ((3)/(5)) = 90^@ + 37^@ = 127^@` w.r.t. the river flow
or `37^@` w.r.t. perpendicular in upstream direction.
.
(b) Resultant velocity or velocity of mass will be
`v_m = sqrt(v^2 - u^2) = sqrt(5^2 - 3^2) = 4 k=km h^-1`
In the direction perpendicular to the river flow.
( c) time taken to cross the river
`t = (d)/(sqrt(v^2 - u^2)) = (1 km)/(4 km h^-1) =(1)/(4) h = 15 min`.
Similar questions