Law of conservation of energy

Definition

The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. The total energy in an isolated system remains constant over time.

5 Must Know Facts For Your Next Test

1. Energy can transform between kinetic, potential, thermal, and other forms but the total amount of energy remains unchanged.
2. In a closed system, the sum of kinetic and potential energy at any point in time is constant.
3. Friction and air resistance often convert mechanical energy into thermal energy, but the total energy still remains constant.
4. The principle applies universally in physics, from simple mechanics to complex thermodynamic processes.
5. $$E_{total} = KE + PE$$ where $$KE$$ is kinetic energy and $$PE$$ is potential energy.

Review Questions

• What does the law of conservation of energy state about the creation and destruction of energy?
• How does friction affect the conservation of mechanical energy?
• In an isolated system, if potential energy decreases by a certain amount, what happens to kinetic energy?

Related terms

Kinetic Energy: The energy possessed by an object due to its motion. It is given by $$KE = \frac{1}{2}mv^2$$ where $$m$$ is mass and $$v$$ is velocity.

Potential Energy: The stored energy an object has due to its position or state. For gravitational potential energy, it is given by $$PE = mgh$$ where $$m$$ is mass, $$g$$ is acceleration due to gravity, and $$h$$ is height.

Thermodynamics: The branch of physics that deals with heat and temperature and their relation to other forms of energy and work. It includes laws governing these relationships.