A railway truck P of mass 2000 kg is moving along a straight horizontal track with speed 10 m s^-1 - Edexcel - A-Level Maths Mechanics - Question 1 - 2003 - Paper 1

To find the speed of truck P after the collision, we use the principle of conservation of momentum:

The momentum before the collision is:

$ext{Initial Momentum} = m_P imes v_P + m_Q imes v_Q = 2000 imes 10 + 3000 imes 0 = 20000 ext{ kg m s}^{-1}$

The momentum after the collision is:

$ext{Final Momentum} = m_P imes v'_P + m_Q imes v'_Q = 2000 imes v'_P + 3000 imes 5$

Setting the initial momentum equal to the final momentum:

$20000 = 2000 v'_P + 15000$

Solving for $v'_P$:

$2000 v'_P = 20000 - 15000$

$2000 v'_P = 5000$

v'_P = rac{5000}{2000} = 2.5 ext{ m s}^{-1}

Therefore, the speed of P immediately after the collision is 2.5 m s^-1.