Forms of energy
- Chemical energy - Energy stored in a fuel and released when chemical reactions take place
- Kinetic energy - Energy stored in a moving object : Ek = 0.5 x mass(kg) x (velocity(m/s))^2
- Gravitational potential energy - Energy of an object due to its position : Eg = mgh
- Elastic energy - Energy stored in a springy object when it is stretched : Ee = 0.5ke^2
- Electrical energy - Energy transferred by electrical current
- Thermal (heat) energy - Energy of an object due to its temperature
Energy is transformed from one form to another.
Energy changes in falling object
When an object is lifted up, it loses kinetic energy and gains gravitational potential energy until maximum altitude is reached. This is when the gravitational potential energy is maximum and kinetic energy is least. When the object is released, it gradually gains kinetic energy and loses gravitational potential energy until it hits the ground when the gravitational potential energy is 0 and kinetic energy is most. But, as it hits the ground, some of the kinetic enrgy is lost due to sound and heat.
Conservation of energy
Energy is neither created nor destroyed, it can only be transformed from one form to another.
Energy in a pendulum :