Question

IF no external force act(or the work done by them is 0) and the internal forces are conservative, the mechanical energy remains constant.

BUT if u consider two charges 1 positive other negative they both attract each other, when we consider them as a system their attraction forces become internal and since force is internal the energy should remain constant which means no work is done but how is this possible since the objects have moved some distance that two with force applied on them

Answer 1

@Vincent-Lyon.Fr help sir

Answer 2

Mechanical energy includes kinetic energy AND potential energy.

In your case, the potential energy will account for the work done by the attractive/repulsive interaction between the charges.

Answer 3

@Vincent-Lyon.Fr yes so the potential energy changes to work so the energy should not remain constant right sir

Answer 4

Mechanical energy = Kinetic energy + Potential energy

Mechanical energy will remain constant but kinetic energy won't.

Answer 5

@Vincent-Lyon.Fr got my mistake i was not consdering the two particle as 1 whole system but i was only looking on 1 particle thnx for help sir

Answer 6

True. This phenomenon if explained chemically can be called the ionic attraction force due to difference in charges.

Answer 7

@Arnab_Chatterjee yes u r right i was slow in understnading thnx

Answer 8

Welcome... :)

Answer 9

As soon as you mention internal forces, it means that both charges belong to the system.

Answer 10

@Vincent-Lyon.Fr I will surely keep that in mind sir.

Answer 11

Correct. @Vincent-Lyon.Fr