Question

A car with a mass of 1.1 × 103 kilograms hits a stationary truck with a mass of 2.3 × 103 kilograms from the rear end. The initial velocity of the car is +22.0 meters/second. After the collision the velocity of the car is -11.0 meters/second. What is the velocity of the truck after this elastic collision?
+13 meters/second
+20 meters/second
+15.7 meters/second
+7.5 meters/second
+9.8 meters/second

Answer 1

elastic collision means conservation of kinetic energy
and there will be conservation of momentum

m = car mass, v = car velocity
M = truck mass, V = truck velocity
1=before and 2 = after collision

m v1 = m v2 + M V2 momentum

(1/2) m (v1)^2 = (1/2) m (v2)^2 + (1/2) M (V2)^2 kinetic energy

plug in the values, keeping track of +- signs

Answer 2

thanks man