Mechanical Engineering - Engineering Mechanics - Discussion

Momentum changes with gravity, and gravity changes from place to place.

Momentum doesn't need constant force, if a body is accelerating in a direction then there must be a constant force applied on it, also the question is asking about SYSTEM OF MASSES, of which momentum can be changed in a by applying force in any direction & not in particularly that direction.

If a body has some constant momentum in one direction, it means that a constant external force is acting on it. But if the momentum has to change in magnitude in that direction then an external unbalanced force has to act.

Here only external force is given and not external unbalanced force hence answer is false.

The law of conservation of energy simply tells that energy in any form can neither be created nor be destroyed. It changes from one form of energy to another form of energy.

It will change by applying force in any direction.

Linear momentum is also a conserved quantity, meaning that if a closed system is not affected by external forces, its total linear momentum cannot change.

In classical mechanics, conservation of linear momentum is implied by Newton's laws; but it also holds in special relativity (with a modified formula) and, with appropriate definitions, a (generalized) linear momentum conservation law holds in electrodynamics, quantum mechanics, quantum field theory, and general relativity.

Law of conservation of energy is first law of thermodynamics where as law of conservation of momentum is Newton's second law and both law are not similar so statement is wrong.

It is true that energy not created nor destroyed transformation of energy from one form to another possible. So given description is wrong.

Answer B is wrong because the given question is Newton second law and not the energy conservation law.

According to conservation of energy: Energy neither created nor destroyed but it can change one form to another.