States & Forms of Energy

• G7 Science
• Secondary Education
• Age 12

States & Forms of Energy

Energy can be in 2 states and 6 forms.

The States of Energy

1. Kinetic energy (KE): every moving object requires energy to set it in motion (which comes from a force). This energy of motion is called kinetic energy.
2. Potential energy (PE): an object may have stored energy due to its position or its condition.

Gravitational Potential Energy

Gravitational potential energy (GPE) is stored in an object due to its physical position and the force of gravity acting upon it.

Energy Transformation

• Potential energy can be transformed into kinetic energy and back again.
  
• Think of a roller coaster or a ski-jumper.
  

KE and Work

• Whenever an object is moving, it has the ability to do work.
  
• E.g. a swinging baseball bat hits a ball and the ball moves in the direction of the force applied to it.
  
• Because every moving object has the ability to do work, every moving object has kinetic energy.
  

PE and Work

• An object does not need to be moving to have the ability to do work.
  
• Think of a stretched elastic band which has the ability to do work when released (the EPE is change to KE).
  
• An object has PE because of its position, condition or chemical composition.
  

__________ is the ability to cause change.
What is the missing word?

1. Force
2. Motion
3. Friction
4. Energy

The faster an object moves, the ______ kinetic energy it has.

1. more
2. less
3. same
4. none of these

Energy due to motion is ________ energy.
What is the missing word?

1. potential
2. energy
3. kinetic
4. friction

__________ is stored energy.
What is the missing word?

1. kinetic
2. potential
3. all of these
4. none of these

Gravitational potential energy depends on the ________ and ________ of the object.

1. height and mass
2. friction and movement
3. mass and movement
4. height and friction

How much potential energy is at the top of a hill on a roller coaster ride?

1. 0%
2. 20%
3. 50%
4. 100%

When you stretch a rubber band, you are storing __________ energy.

1. kinetic
2. potential
3. none of these
4. all of these

The Forms of Energy

What are the various forms of energy around us?

Chemical Energy

• Chemical energy is the (potential) energy stored in the chemical bonds of substances.
  
• Examples: fuels (coal, gas, sugar), batteries, matches, etc.
  

Electrical Energy

• Electrical energy is the (kinetic) energy of moving electric charges called electrons.
  

Radiant Energy

• Radiant energy is the energy transferred by electromagnetic radiation.
  
• Examples: light, x-rays, gamma rays, thermal radiation (heat), etc.
  

Nuclear Energy

• Nuclear energy is the (potential) energy stored in the nucleus of an atom.
  
• When the nuclei of atoms are split (fission) or fused together (fusion), nuclear energy is released. 
  

Thermal Energy

• Thermal energy is the total (kinetic) energy of all the particles that make up an object.
  
• Particles move faster at higher temperatures.
  
• Higher temperatures increases thermal energy.
  

Mechanical Energy

• Mechanical energy is the energy of an object due to its movement (kinetic energy) and/or position (potential energy).
  
• Kinetic energy is the energy of motion.
  
• Potential energy is the energy of position or condition.
  
• We will look at kinetic and potential energy later.

Sound Energy

• Sound energy is the result of when a force makes an object vibrate e.g. plucking a guitar string.
  
• Sound travels as waves through matter e.g. air.
• Sound energy is a form of mechanical energy.

Elastic Energy

• Elastic energy is the mechanical (potential) energy stored in a material due to its condition.
  
• Examples: stretching (an elastic band) or compression (of a spring).
  

This energy is related to the potential energy stored in the bonds between atoms.

1. sound
2. electrical
3. chemical
4. nuclear

This energy is related to the motion of atoms or molecules in a substance.

1. chemical
2. thermal
3. nuclear
4. sound

This energy is related to the vibrations of atoms or molecules.

1. sound
2. chemical
3. electrical
4. radiant

This energy is related to the condition of a material such as stretching or compressing it.

1. electrical
2. chemical
3. sound
4. elastic

This energy is related to the energy stored in the nuclei of atoms that can be related by either fission or fusion.

1. chemical
2. electrical
3. nuclear
4. mechanical

This energy is related to the movement of electrons down a wire to create light in a lamp.

1. nuclear
2. electrical
3. chemical
4. sound

This energy is related to the electromagnetic radiation produced by the Sun.

1. radiant
2. nuclear
3. mechanical
4. thermal

This energy is related to the relative position and movement of an object.

1. thermal
2. mechanical
3. electrical
4. sound