Explain the law of conservation of energy then give an example that shows the slot to be true in your example explain where there is potential energy and where there is kinetic energy also explain if any energy is lost to friction

The energy of a system always remains constant as it can be converted from one type two another type. It can never be lost or created.

Lets take an example of the boy riding a bicycle.

The boy is using the biochemical energy in his body to run the pedals up and down in a cycle form.

The biochemical energy is converted into the potential energy in the pedal.

As the pedal moves, it gives energy to move the wheels of the cycle and consequently the cycle will move forward.

Hence the potential energy is converted into the kinetic energy.

If the road is not clear, a lot of energy is needed to move the wheels or cycle as compared to clear road. Because some of the energy will be converted into heat during friction.