Question

A 1300 kg car traveling at 35 mph rear-ends a 1000 kg car traveling 25 mph. Just after the collision (but before the driver’s slow down to pull over), the 1300 kg car is slowed to 30 mph and the 1000 kg car is sped up to 31.5 mph. Was momentum conserved in the collision? Was energy conserved in the collision? Show all work. If momentum or energy was lost, calculate how much and discuss where it could have gone.?

Answer 1

given,

before collision

mass of car A = m_a = 1300 kg

velocity of car A = v_a = 35 mph

mass of car B = m_b= 1000 kg

velocity of car B = v_b = 25 mph

after collision

V_a = 30 mph

V_b = 31.5 mph

Initial momentum

`P_1 = m_av_a + m_b v_b`

`P_1 = 1300 * 35+ 1000 * 25`

`P_1 =70500 Kg.m/s`

final momentum

`P_2 = m_aV_a + m_b V_b`

`P_2 = 1300 * 30+ 1000 * 31.5`

`P_2 =70500 Kg.m/s`

here initial momentum is equal to the final momentum of the car.

hence, momentum is conserved in the collision.