Mechanical Engineering - Engineering Mechanics - Discussion

According to conservation of energy principle. Energy cannot be created nor be destroyed. It can only be transferred from one source to another.

According to conservation of energy principle. Energy can neither be created nor be destroyed. It can only be transferred from one form to another.

Energy conservation should not be confused with linear momentum. Whilst one concerns itself with the fact that energy cannot be created or lost, the other is focused on changes that can happen within a system of masses moving in a particular direction when external forces are applied. Is there a change in system energy when momentum changes? Possibly.

Kinetic energy of a moving system of masses is 0.5 x (m1 x v1^2 + m2 x v2^2 x ......mn x vn^2). The mass of objects will not change unless some molecular distortion occurs which is not treated herein. However, the velocity can reduce or increase.

Hence, the system energy can go up or go down. However, if this is happening in a closed system, the kinetic energy lost becomes gained as heat energy. Hence, total energy remains unchanged. But if this is not a closed system, then energy is exchanged across our artificial boundary which contains the system of masses, and therefore system energy changes.

So, the key word here for the statement to be true is whether the system is CLOSED or OPEN. And, since we were not informed on this, the assumption is that it is an OPEN system in which case the correct answer is FALSE because the energy conservation principle will NOT hold in an OPEN system.

That question is based on newton 1st law of motion. According to this law, every body that time up to not motion then not external force are applied.

The rate of change of momentum is directly proportional to the applied force, as stated in the newtons second law of motion.

So, the answer is A(true).

The question related to the Newtons Second law of motion, whereas the law of conservation of energy is different.

According to the principle of conservation of energy, the total momentum of a system of masses in Straight line remains constant unless acted upon by an external force in that direction.

The law of conservation of energy states that in a closed system the total amount of energy is conserved and does not change. This means that energy may change from one form to another, but that the total amount of energy in the closed system remains constant.

According to conservation law of energy, energy neither created nor destroyed, it changes its form from one type of energy to another type of energy.

According to the law of conservation, all momentum of the system will remain constant in any direction without acting any force in that direction. It will change when any force will act in that direction.