What is Energy?
- Energy is measured in joules and is the ability to work.
- Energy can be stored in a variety of forms.
- Energy is never created or destroyed, but it is only converted to other forms of energy.
- There is however a term called "energy degradation" where energy can change into forms that might not be useful for us.
What is Work?
- In physics, work is defined as the process of changing the form of energy.
- For example, if you were to lift a dumbbell, you'd be using the chemical energy stored in your body in order to give the dumbbell potential energy.
- A force is said to do work when it acts on an object, and it transfers energy to it.
- The work done by a force is calculated by multiplying the displacement of the object upon which the force acts and the component of the force that is parallel to the object’s displacement.
- Work can also be calculated through graphs.
Kinetic Energy
- The equation for kinetic energy, which is the energy of a moving object, is shown below.
- At constant velocity, energy is proportional to mass. This would mean that doubling the mass would double the energy.
Gravitational Potential Energy
- At heights, objects have gravitational potential energy.
- For example if you drop a rock then all its gravitational potential energy is converted into kinetic energy, and soon heat and sound when it hits the ground.
- The equation for gravitational potential energy is shown below.
Elastic Potential Energy
- Work can also be stored as elastic potential energy in a spring (or another elastic object such as a rubber band).
- Letting go of the spring transfers its elastic potential energy into kinetic energy (and thermal energy and a little sound).
- The equation for elastic potential energy is shown below.
