Answer:
As it falls, its mechanical energy is conserved, but its momentum is not conserved.
Explanation:
The mechanical energy of the egg during the fall is the sum of its potential energy and its kinetic energy:
E = U + K
As we know, mechanical energy is always conserved when there are only conservative forces acting on a system. In this case, the only force acting on the egg is the force of gravity, which is a conservative force (we are neglecting air resistance), therefore mechanical energy is conserved.
In particular, as the egg falls down, its gravitational potential energy U decreases, while its kinetic energy K increases (since its speed increases), but the sum of the two quantities, E, remains constant.
On the contrary, momentum is not conserved. In fact, momentum is given by
p = mv
where m is the mass and v is the velocity. Since the velocity of the egg increases (in magnitude) while it falls down, it means that momentum is not constant, so it is not conserved.
Why? The reason is the following: momentum is only conserved when the net external force acting on the system is zero. This is not the case: in fact, there is a net external force acting on the egg (the force of gravity), so the momentum cannot be conserved.
