After a completely inelastic collision two objects of the sa

After a completely inelastic collision, two objects of the same mass and same initial speed move away together at half their initial speed. find the angle between the initial velocities of the objects.

a. 120 degrees

b. 60 degrees

c. 45 degrees

d. 30 degrees

e. 90 degrees

Solution

From the law of momentum conservation

m u cos theta / 2 + m u costheta / 2 = (m + m) * 1/2 u

2 m u cos theta / 2 = m u

cos theta / 2 = 1/2

theta / 2 = 60

theta = 120 degrees