Question

two trucks of mass 5 tonne and 7 tonne are moving in the opposite direction with a speed of 54km/hr and 72km/hr calculate their speed after collision if they are crush into each other and become one​

Answer 1

GIVEN:-

Before Collision:-

• $\rm{Mass\:of\:first\:truck (m_1)= 5\:tonnes = 5000kg}$

• $\rm{Mass\:of\:second\:truck(m_2) = 7\:tonnes= 7000kg}$

• $\rm{Initial\:Velocity\:of\:m_1 = 54km/hr = 15m/s}$

• $\rm{Initial\:Velocity\:of\:m_2 = 72km/hr = 20m/s}$.

After Collision

• $\rm{Mass\:of\:first\:truck (m_1)= 5 tonnes}$

• $\rm{Mass\:of\:second\:truck(m_2) = 7 tonnes}$

• $\rm{ Final\:Velocity = v_1 = v_2= ?}$

TO FIND:-

• Their speed after collision if they are crush into each other and become one.

According to the Conservation of momentum

$\implies\rm{ Before\: Collision = After\: Collision}$

$\implies\rm{ m_1u_1 + m_2u_2 = m_1v_1 + m_1v_2}$

$\implies\rm{5000\times{15} + 7000\times{20} = (5000+7000)v}$

$\implies\rm{ 75000 + 140000= 12000v}$

$\implies\rm{ 215000 = 12000v}$

$\implies\rm{ v = \dfrac{215000}{12000}}$

$\implies\rm{ v = 17.9m/s^{-1}}$.

Hence, The Final Velocity will be 17.9m/s^-1