Question

A car of mass 1000 kg, travelling at 20m/s collides with another car B of mass 2000kg
travelling at 25m/s in the same direction. After collision the velocity of car A becomes 15m/s.
Calculate the velocity of car B after collision.

Answer 1

Explanation:

The given items in the question are :

Mass 1 = 1000 kg

Mass 2 = 2000 kg

Velocity (u¹) = 20 m/s

Velocity (u²) = 25 m/s (not u square)

Velocity Final ( v¹) = 15 m/s

Velocity Final (v²) = ? (not v square)

$\sf{———————————————}$

[Where u¹ and v¹ are initial and final velocities of car A]

[Where u² and v² are initial and final velocities of car B]

Note this formula:

$\boxed{\sf{m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2}}$

Replace the values in the formula :

$\sf{m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2}$

$\sf{1000 \times 20 + 2000 \times 25 = 1000 \times 15 + 2000 \times v_2}$

$\sf{20000 + 50000 = 15000 + 2000 \times v_2}$

$\sf{70000 = 15000 + 2000 \times v_2}$

$\sf{55000 = 2000 \times v_2}$

$\sf{\dfrac{55000}{2000} = v_2}$

$\sf{27.5 = v_2}$

So, the answer is 27.5 m/s.

Answer 2

Answer:

Explanation:

Please check the attached file

Velocity of car B after collision = 27.5