Nature of Energy and Energy Conservation

What is Energy?

Energy is the ability to do work or cause change. It is a scalar quantity measured in Joules (J). Energy is not tangible but is fundamental to all physical processes. It exists in various forms and can be transformed, but it is always conserved.

Law of Conservation of Energy

Energy cannot be created or destroyed; it can only be transformed from one form to another.
The total energy of an isolated system remains constant over time.

Kinetic energy at point A is 5J. The potential energy at point A is 10J. At point B, the potential energy is 0J. Find the kinetic energy at point B

At point A:

Kinetic Energy: \( KE_A = 5J \)
Potential Energy: \( PE_A = 10J \)

At point B:

Potential Energy: \( PE_B = 0J \)
Find: \( KE_B \)

Using conservation of energy:

\( KE_A + PE_A = KE_B + PE_B \)
\( KE_B = KE_A + PE_A - PE_B \)
\( KE_B = 5J + 10J - 0J = 15J \)

Written by Thenura Wickramaratna