Assume: Moving to the right is positive. A (n) 7.7 g object moving to the right at 22 cm/s makes an elastic head-on collision with a 18 g object moving in the opposite direction at 14 cm/s. 7.7 g 22 cm/s 18 g 14 cm/s Find the velocity of the first object immediately after the collision. Answer in units of cm/s.

We shall apply the formula for velocity in case of elastic collision which is given below

v₁ = (m₁ - m₂) u₁ / (m₁ + m₂) + 2m₂u₂ / (m₁ + m₂)

m₁ and u₁ is mass and velocity of first object, m₂ and u₂ is mass and velocity of second object before collision and v₁ is velocity of first velocity after collision.

Here u₁ = 22 cm / s, u₂ = - 14 cm / s. m₁ = 7.7 gm, m₂ = 18 gm

v₁ = (7.7 - 18) x 22 / (7.7 + 18) + 2 x 18 x - 14 / (7.7 + 18)

= - 8.817 - 19.6

= - 28.4 cm / s