Answer:
Velocity of the car decreases.
Explanation:
We can understand the situation if we apply the conservation of energy principle to the situation
Let the initial mass of the freight be [tex]m_{f}[/tex]
Initial velocity of the freight be [tex]v_{fi}[/tex]
Thus the initial Kinetic energy of the freight will be [tex]K.E=\frac{1}{2}m_{f}v_{if}^{2}[/tex]
When a Coal Block of mass M falls into the freight it's energy will become
[tex]K.E=\frac{1}{2}(m_{f}+M)v_{ff}^{2}[/tex]
Equating both the energies we get final velocity as[tex]v_{ff}[/tex]
[tex]\frac{1}{2}m_{f}v_{if}^{2}=\frac{1}{2}(M+m_{f})v_{ff}^{2}\\\\v_{ff}=\sqrt{\frac{m_f}{(M+m_{ff})}}\cdot v_{if}[/tex]
As we see that [tex]\sqrt{\frac{m_f}{(M+m_{ff})}}[/tex] is less than 1 we can infer that velocity decreases.
