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QJEEM21Ph1c73: JEE Main 2021 Physics - Class 11 JEEM21Ph1c73 Solution: A ball with a speed of 9 m/s collides with another identical…

A ball with a speed of 9 m/s collides with another identical ball at rest. After the collision, the direction of each ball makes an angle of 30 ∘^\circ with the original direction. The ratio of velocities of the balls after collision is x : y, where x is __________.

Step-by-Step Verified Solution

The situation is shown below

JEE Main 2021 (Online) 24th February Morning Shift Physics - Center of Mass and Collision Question 64 English Explanation
Using conservation of linear momentum in y-direction,

pi = pf

As, pi = 0

and pf = mv1 sin30 ∘^\circ −- mv2 sin30 ∘^\circ

⇒\Rightarrow 0 = m ×\times 12{1 \over 2} v1 −- m ×\times 12{1 \over 2} v2

⇒\Rightarrow v1 = v2 or v1 : v2 = 1 : 1

Since, v1 : v2 = x : y (given)

∴\therefore x = 1

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