A ball with mass m=1kg and speed vo=5m/sec elastically collides with a stationary, identical ball (all resting on a frictionless surface so gravity is irrelevant). A student measures the top ball emerging from the collision at at speed vt=4m/sec at an angle ϴt ≈ 37°.

Question

a) Find the speed vb of the other ball.

b) Find the angle ϴb of the other ball.

c) What does ϴt+ϴb add up to?

Answer 1

a,b. M1*V1 + M2*V2 = M1*V3 + M2*V4.
1*5 + 1*0 = 1*4[37o] + 1*V4.
5 = 4[37o] + V4, V4 = 5-4[37O],
V4 = 5-4*Cos37-4*sin37 = 5-3.19-2.41i = 1.81 - 2.41i = 3.01m/s[-53.1o] = 3.01m/s[53.1o] S. of E. = Velocity and Direction.

c. A1+A2 = 37 + 53.1 = 90.1o.