A 3 kg toy car with a speed of 7 m/s collides head-on with a 2 kg car traveling in the opposite direction with a speed of 5 m/s. If the cars are locked together after the collision with a speed of 2.20 m/s, how much kinetic energy is lost?

Answers:

kinetic energy lost = 86.4J

Explanation:

let Kf be the kinetic energy after the collision and Ki be the kinetic energy before the collision. let the 3kg car be 1 and 2kg car be 2.

Kf = K1 (f) + K2 (f)

Ki = K1 (i) + k2 (i)

loss in kinetic energy = Kf - Ki

= 1/2 (3) (2.20) ^2 + 1/2 (2) (2.20) ^2 - 1/2 (3) (7) ^2 - 1/2 (2) (-5) ^2

= 12.1 - 98.5

= - 86.4 J

therefore, the kinetic energy lost in the collision is 86.4 J.