Home
Class 11
PHYSICS
A man who can swim at a velocity v relat...

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

The minimum time in which he can cross the river is `b/v`

B

He can reach a point exactly opposite on the bank in time `t=b/sqrt(v^2 - u^2) if vgtu`

C

He cannot reach a point exactly opposite on the bank if `ugtv`

D

He cannot reach a point exactly opposite on the bank if `vgtu`

Text Solution

Verified by Experts

The correct Answer is:
A, B, C
For minimum time
`:. t_(min)=b/v`

For reaching a point exactly opposite

Net velocity=`sqrt(v^2-u^2) ("but" vgtu)`
`:. t=b/("net velocity")`
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • KINEMATICS

    DC PANDEY|Exercise Comprehension|7 Videos

  • KINEMATICS

    DC PANDEY|Exercise Subjective Questions|24 Videos

  • KINEMATICS

    DC PANDEY|Exercise Subjective|51 Videos

  • GRAVITATION

    DC PANDEY|Exercise (C) Chapter Exercises|45 Videos

  • KINEMATICS 1

    DC PANDEY|Exercise INTEGER_TYPE|15 Videos

Similar Questions

Explore conceptually related problems

A man can swim with velocity v relative to water. He has to cross a river of width d flowing with a velocity u (u gt v) . The distance through which he is carried down stream by the river is x. Which of the following statements is correct?

A man can swim in still water with speed v . He wants to cross a river of width d that flows with speed u and reaches the point directely opposite to his starting point. (a) In which direction should he try to swim (i.e., find the angle the makes with the river flow)? (b) much time will he take to cross the river ?

Knowledge Check

  • A man who can swim at a speed v relative to the water wants to cross a river of width d, flowing with a speed u. The point opposite him across the river is P.

    A
    The minimum time in which he can cross the river is `(d)/(v)`
    B
    He can reach the point P in time `(d)/(v)`
    C
    He can reach the point P in time `(d)/(sqrt(v^(2)-u^(2))`
    D
    He cannot reach P if `u gt v`

  • A man who can swim at a speed v relative to the water wants to cross a river of width d flowing with a speed u. The point opposite him across the river is A.

    A
    He can reach the point A in time d/v
    B
    He can reach the point A is time `(d)/(sqrt(v^(2)-u^(2)))`
    C
    The minimum time in which he can cross river is `d/v`
    D
    He can not reach A if u gt v

  • A man can swim with velocity v relative to water. He has to cross a river of width d flowing with a velocity u(u gt v). The distance traveled by man along the flow is x, when he reaches to opposite bank. For x to be minimum the person should swim at an angle alpha with the direction of the flow of water, where alpha is

    A
    `sin^(-1)(v//u)`
    B
    `sin^(-1)(u//v)`
    C
    `(pi)/2+sin^(-1)(v//u)`
    D
    `(pi)/2+sin^(-1)(u//v)`

    • Similar Questions

    Explore conceptually related problems

    A man can swim at a speed of 3 km/h in still water. He wants t cross a 500 m wide river flowing at 2 km/h. He flow at an angle of 120 with the river flow while swimming. A. Find the time he takes to cross the river. b.At what point on the opposite bank will he arrive?

    A man can swim with a speed v relative to water . There is a river of width d which is flowing at a speed u . A is the point on river bank from where he starts and B is point directly opposite to A on the other side of the river .

    A boat crossing a river moves with a velocity v relative to still water. The river is flowing with a velocity v/2 with respect to the bank. The angle with respect to the flow direction with which the boat should move to minimize the drift is–

    A man swims to and fro along the bank of a river with a velocity v relative to water. If the velocity of flow is u , the average speed of the man (for to and fro motion) is :

    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

    Home
    Profile