Non-conservative forces, like friction and air resistance, make it harder to follow the Law of Conservation of Energy. This law tells us that in a closed system, the total amount of energy stays the same. Energy can change forms, but it cannot be created or destroyed. Non-conservative forces make this idea a bit more complicated.

1. Energy Loss:

   • Non-conservative forces take mechanical energy (which is the sum of kinetic and potential energy) and turn it into thermal energy (heat). This means some energy is lost and can’t be used.
   • For example, when calculating the work done against friction, you can use this formula:
     $W_{\text{friction}} = f_{\text{friction}} \cdot d$
     Here, ( f_{\text{friction}} ) is the force of friction, and ( d ) is how far something moves.

2. Efficiency:

   • In systems that deal with non-conservative forces, the efficiency is often less than 100%. For example, in machines like engines, the efficiency might only be between 20% and 40% because energy is lost to friction and heat.

3. Energy Changes:

   • In real life, when potential energy changes to kinetic energy, some energy is usually lost to non-conservative forces. For instance, if a marble rolls down a hill, not all its potential energy
     $PE = mgh$
     (where ( m ) is mass, ( g ) is gravity, and ( h ) is height) becomes kinetic energy
     $KE = \frac{1}{2}mv^2$
     because of the work done against friction.

In summary, while the Law of Conservation of Energy is generally true, non-conservative forces show us how tricky it is to keep energy in usable forms in moving systems.