Home

Science

Physics - Energy

Energy

Energy is the ability to cause change or to do work.

Energy comes in many, many forms; some of the most common forms we experience on earth are: heat, light, and movement.

Energy is the impetus behind all motion and all activity.

Energy is separated into two different categories: Potential and Kinetic.

Potential Energy

Potential energy is energy that is "stored" i.e. not being used.

This can mean any type of energy that is not being spent. For example, a book that is carried to the top of a tower has potential energy;

It has potential energy because it is acting against gravity.

circular stairway

Potential Energy

In physics, every action has an equal and opposite reaction.

The action was the book being elevated to the top of the tower. And the reaction would be the book falling or otherwise descending to the ground. This is only one type of potential energy, potential energy can exist in many states such as:

  • Food (broken down into simple components and expended by respiration)
  • Electric Current (stored in batteries, or generators)
  • Springs (mechanical devices, when expanded or contracted too far)

Potential Energy

Which of the following is an example of potential energy?

  1. a battery in a flashlight that is on.
  2. a battery in a flashlight that is off.

a flashlight

Potential Energy

Which of the following is an example of potential energy?

  1. a battery in a flashlight that is on.
  2. a battery in a flashlight that is off.
    The battery in the flashlight that is off has the potential to turn on.

a flashlight

Potential Energy

Which of the following is an example of potential energy?

  1. a pogo stick in the garage.
  2. a poto stick that is being used.

person holding a pogo stick

Potential Energy

Which of the following is an example of potential energy?

  1. a pogo stick in the garage.
    The pogo stick still in the garage has the potential to be used.
  2. a poto stick that is being used.

person holding a pogo stick

Kinetic Energy

Kinetic energy is energy that is in use.

Kinetic energy is the energy that radiates, moves, shines, and heats.

This type of energy is very common in our universe.

Kinetic energy is very, very changeable; all its forms are interchangeable.

As shown below:

  • Motion → Heat (through conduction)
  • Heat → Motion (through convection)
  • Light → Heat (through radiation)

Types of Kinetic Energy

Motion is the type of kinetic energy that moves physical objects through space.

Heat is the type of kinetic energy that moves the molecules of a physical object. This causes the objects temperature to rise.

Light is the type of energy that radiates through space in waves and beams. Light is categorized into a spectrum. Visible light is the light we can see reflected off of objects, while other types of light such as x-rays, gamma rays, and radio waves cause radiation.

Types of Kinetic Energy

Which of the following is NOT an example of kinetic energy?

  1. Baking a pie in the oven.
  2. Turning on the oven light.
  3. An empty, unheated oven.

items baking in an oven

Types of Kinetic Energy

Which of the following is NOT an example of kinetic energy?

  1. Baking a pie in the oven.
  2. Turning on the oven light.
  3. An empty, unheated oven.
    An empty oven has potential energy, not kinetic (in use).

items baking in an oven