00:01
So here in first part of this question, let's use the conservation of momentum to solve for the final speed of the last massive ball.
00:08
The initial momentum of the system is mv plus 2mv and that is equals to 3mv.
00:16
And the final momentum of the system is mu plus 2mv.
00:22
Since there are no external forces, the initial momentum must equal to the final momentum.
00:27
And solving for u, we get u is equals to mv.
00:32
The angle theta can be found using the trigonometric relationship that is tan theta is equals to v by u.
00:40
And plugging in the values of u, we get tan theta is equals to v by mv.
00:47
This simplifies to tan theta is equals to 1.
00:52
So theta comes out to be 45 degrees.
00:59
Now in second part of this question, in the second part, the kinetic energy of the system is represented by ke and that is equals to half mv squared...