A ball moving with velocity 2 m/s collides head on with

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A ball moving with velocity 2 m/s collides head on with another stationary ball of double the mass. If the coefficient of restitution is 0.5, then their velocities (in m/s) after collision will be :

1. 0, 1
2. 1, 1
3. 1, 0.5
4. 0, 2

Correct Option: A

Clearly v₁ = 2 ms^–1, v₂ = 0
m₁ = m (say), m₂ = 2m
v₁' = ?, v'₂ = ?

e =	v₁' - v₂'	....(i)
	v₂ - v₁

By conservation of momentum, 2m = mv₁' + 2mv₂'... (ii)
From (i),

0.5 =	v₂' - v₁'
	2

∴ v₂' = 1 + v₁'
From (ii), 2 = v₁'+ 2 + 2 v₁'
v₁' = 0 and v₂' = 1 ms^–1