Question

A rifle shoots a projectile of mass 1kg into a block. The speed of the projectile before it hits is 100m/s. The projectile sticks in the block and they move together at 2 m/s. What is the mass of the block, in kg

Answer 1

To solve this problem it is necessary to apply the conservation equations of the momentum, for which it allows us to find the mass of object two, which was the product of an inelastic shock. Mathematically the momentum can be described as

`m_1v_1+m_2v_2 = (m_1+m_2)V_f`

Where,

`m_(1,2)` = Mass of each object

`v_(1,)2` = Velocity of each object

`V_f`= Final Velocity

Our values are given as,

`m_1 = 1 kg`

`v_1 = 100 m/s`

`v_2 = 0 \rightarrow` The block remains at rest

`V_f = 2 m/s`

Substituting,

`m_1v_1+m_2v_2 = (m_1+m_2)V_f`

`1*100 + 0 = (1 + m_2)*2`

`100 = 2 + 2m_2`

`98 = 2m_2`

`m_2 = 49 kg`

Therefore the mass of the block is 49Kg.