Question

Two 100 kg bumper cars are moving toward each other in opposite directions. Car A is moving at 8 m/s and Car B at –10 m/s when they collide head–on. If the resulting velocity of Car B after the collision is 8 m/s, what is the velocity of Car A after the collision?
(I saw this question was asked previously, but the person did not provide the correct answer...)

Answer 1

Answer:

$v_a = -10 m/s$

so car A will move with speed 10 m/s in opposite direction

Explanation:

As we know that when two cars collide then the momentum of two cars will remains conserved

so here we have

$P_i = P_f$

mass of two cars = 100 kg

speed of car A = 8 m/s

speed of car B = - 10 m/s

after collision the speed of car B = +8 m/s

now by momentum conservation equation

$m_1v_{1i} + m_2v_{2i} = m_1v_{1f} + m_2v_{2f}$

so we have

$100(8) + 100(-10) = 100(v_a) + 100(8)$

so we have

$v_a = -10 m/s$

so car A will move with speed 10 m/s in opposite direction