Home
Class 12
PHYSICS
A river of width d is flowing with a vel...


A river of width d is flowing with a velocity u. A person starts from point A. He always try to keep himself along y axis. Speed of man w.r.t to river at any position is given by `v=ksqrt(y)(kto+ve` constant). Time taken by man to cross the river is (Assume that at t=0,y=0)

A

`sqrt((d)/(k))`

B

`2sqrt((d)/(k))`

C

`(2sqrt(d))/(k)`

D

`(2d)/(sqrt(k))`

Text Solution

Verified by Experts

The correct Answer is:
C
`t=int(dy)/(V_(y))=underset(0)overset(d)int(dy)/(Ky^(1//2))=(2sqrt(d))/(k)`
Promotional Banner

Similar Questions

Explore conceptually related problems

A river of width 100 m is flowing with a velocity of 1.5 m/s. A man start from one end with rest relative the river. He raws with an acceleration of 2 m//s^(2) relative to the river. If the man want to cross the river in minimum time, by how much distance (in meters) will he be drifted (flown) in the direction of river flow during the crossing.

A river of width omega is flowing with a uniform velocity v. A boat starts moving from point P also With velocity v relative to the river. The direction of resultant velocity is always perpendicular to the line joining boat and the fixed point R. Point Q is on the opposite side of the river. P, Q and R are in a straight line. If PQ=QR=omega, find (a) the trajectory of the boat, (b) the drifting of the boat and (c) the time taken by the boat to cross the river.

A man can swim at a speed of 5 km/h W.r.t water. He wants to cross a 1.5 km wide river flowing at 3 km/h. He keeps himself always at an angle of 60° with the flow of direction while swimming, The time taken by him to cross the river will be

A swimmer crosses a river of width d flowing at velocity v. While swimming, he keeps himself always at an angle of 120^(@) with the river flow and on reaching the other end. He finds a drift of d/2 in the direction of flow of river. The speed of the swimmer with respect to the river is :

A man who can swim at a velocity v relative to water wants to cross a river of width b, flowing with a speed u.

A man who can swim at a velocity v relative to water wants to cross a river of width b, flowing with a speed u.

Two ports, A and B, on a north-south line ar separated by a river of width D. The river flows east with speed u. A boat crosses the river starting from port A. The speed of the boat relative to the river is v. Assume v=2u Q. Suppose the boat wants to cross the river from A to the other side in the shortest possible time. Then what should be the direction of the velocity of boat relative to river?

A man can row a boat with 4km/h in still water, if he is crossing a river where the current is 2 km/h. (a) In what direction will his boat be holded, if he wants to reach a point on the other bank, directly opposite to starting point? (b) If width of the river 4km, how long will the man take to cross the river, with the condition in part (a)? (c) In what direction shou ld he heat the boat if he wants to cross the river in shorest time and what is this minimum time? (d) How long will it take him to row 2 km up the stream and then back to his starting point?

A man can swim at a speed of 3 km h^-1 in still water. He wants to cross a 500-m wide river flowing at 2 km h^-1 . He keeps himself always at an angle to 120^@ with the river flow while swimming. The time taken to cross the river is.

A man can swim in still water at a speed of 6 kmph and he has to cross the river and reach just opposite point on the other bank. If the river is flowing at a speed of 3 kmph, and the width of the river is 2 km, the time taken to cross the river is (in hours)