A mass m moving horizontally (along the x-axis) with velocity

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A mass m moving horizontally (along the x-axis) with velocity v collides and sticks to mass of 3m moving vertically upward (along the y-axis) with velocity 2v. The final velocity of the combination is

1. 1 vî - 3 vĵ
  4 2
2. 1 vî + 2 vĵ
  3 3
3. 2 vî + 1 vĵ
  3 3
4. 3 vî + 1 vĵ
  2 4

Correct Option: A

As the two masses stick together after collision, hence it is inelastic collision. Therefore, only momentum is conserved.

∴ mvî + 3m(2v)ĵ = (4m)v^{^→}

v^{^→} =	v	î +	6	vĵ
	4		4

=	v	î +	3	vĵ
	4		2

	1	vî -	3	vĵ
	4		2

	1	vî +	2	vĵ
	3		3

	2	vî +	1	vĵ
	3		3

	3	vî +	1	vĵ
	2		4