Question

What is the speed of the first marble immediately after the collision?


What is the speed of the second marble immediately after the collision?

Answer 1

m1 = mass of first marble = 0.050 kg

m2 = mass of second marble = 0.020 kg

v1i = 2 m/s

v2i = 0

v1f = ?

v2f = ?

using conservation of momentum

m1 v1i + m2 v2i = m1 v_1f + m2 v_2f

0.05 x 2 + 0.02 x 0 = 0.05 v_1f + 0.02 v_2f

v_2f = (0.1 - 0.05 v_1f )/0.02                       eq-1

using conservation of kinetic energy

m₁ v²1i + m₂ v²2i = m₁ v²_1f + m₂ v²_2f

0.05 x 2² + 0.02 x 0² = 0.05 v²_1f + 0.02 ((0.1 - 0.05 v_1f )/0.02)²

V_1f = 0.86 m/s

using eq-1

v_2f = (0.1 - 0.05 v_1f )/0.02 = (0.1 - (0.05) (0.86))/(0.02) = 2.85