Question

a ball moving with velocity of 9m/s collides with another similar stationary ball. After the collision both the balls move in directions making an angle of 30 degree with the initial direction. After the collision their speed will be-

1) 2.6m/s
2) 5.2m/s
3)0.52m/s
4)52m/s

Answer 1

Conservation of linear momentum in the direction perpendicular to the initial velocity : 
                   m v1 sin 60° - m v2 sin 60° = 0
                    v1 = v2

conservation of linear momentum in the direction of initial velocity of the first ball:     
             m u  =  m v1 cos 30° + m v2 cos 30°
             9  = 2 v cos 30 = 2√3 v

              v = 3√3  /2  m/s = 2.6 m/s

Answer 2

Answer:

very easy just apply basic concepts