Physics - Kinematics Question with Solution | TestHub

PhysicsKinematicsRelativeMedium2 minQB

PhysicsMediumnumerical

Passage / Comprehension

A swimmer wishes to cross a river from A. If he swims perpendicular to the flow of the river, he takes 10 min to cross the river and reaches point C, at a distance of 120 m downstream from the opposite point B. If he swims at an angle $α$ such that he directly reaches B, it takes him 12.5 minutes to reach the other end. (Assuming he crosses the river with constant velocity)

If instead moving with constant velocity he starts swimming perpendicular to the flow from rest with constant acceleration of $1 m / sec^{2}$ then time taken by him to cross the river is (in s) :

Answer:

20.00

Solution:

$\frac{d}{v} = 10 min .$ $u \times 10 min . = 120 m$

$\frac{v ^{2} - u ^{2}}{d} = 12.5 min .$

$u = 12 m / min .; v = 20 m / min .; d = 200 m$

$200 m = 0 \times t + \frac{1}{2} \times 1 \times t^{2}$

$t = 20 sec . = \frac{1}{3} min .$

Stream:JEESubject:PhysicsTopic:KinematicsSubtopic:Relative

⏱ 2mℹ️ Source: QB

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