Question

car a of mass 1500 kg travelling at 25 m/s collides with another car B of mass 1000 kg travelling at 15m/s in the some direction. After collision, the velocity of car becomes 20 m/s. culculate the velocity of car B after collision.​

Answer 1

Given :

Mass of car A = 1500kg

Mass of car B = 1000kg

☆ Before collision :

• Velocity of car A, u₁ = 25m/s
• Velocity of car B, u₂ = 15m/s

☆ After collision :

• Velocity of car A, v₁ = 20m/s

To find :

Velocity of the car B after collision

Solution :

here, we have to use law of conservation of Momentum.

Law of conservation of momentum states that, when external force acting on a system is zero, then total momentum of the system remains constant.

As per the law of conservation of Momentum

Initial momentum = final momemtum

$\leadsto{ \sf m_1u_1+ m_2u_2 = m_1v_1 + m_2v_2}$

$\leadsto{\sf (1500)(25) + (1000)(15) = (1500)(20) + (1000)(v_2)}$

$\leadsto{ \sf 37500 + 15000 = 30000 + 1000v_2}$

$\leadsto{ \sf 52500 = 30000 + 1000v_2}$

$\leadsto{ \sf 52500 - 30000 = 1000v_2}$

$\leadsto{ \sf 22500 = 1000v_2}$

$\leadsto{ \sf \dfrac{22500}{1000} = v_2}$

$\leadsto \sf v_2 = 22.5m/s$

Thus, velocity of car B after collision is 22.5m/s.