4th Grade Science
Physics of Light, Sound, Force and Motion
Unit 4
Conservation of Energy
Conservation of Energy
Energy is all around us and even within us. Energy is there whenever there are moving objects, sound, light or heat.
Energy is all around us and even within us. Energy is there whenever there are moving objects, sound, light or heat.
When objects collide, energy is transferred from one object to another.
When objects collide, energy is transferred from one object to another.
Energy cannot be created or destroyed, only transferred from one medium to another.
Energy cannot be created or destroyed, only transferred from one medium to another.
Light
Light
We all have looked at a rainbow and wonder how after rain, colors can appear out of nowhere. Rainbows and mirrors can do what they do because of 2 characteristics of light:
We all have looked at a rainbow and wonder how after rain, colors can appear out of nowhere. Rainbows and mirrors can do what they do because of 2 characteristics of light:
- Reflection: light bounces off a surface (shiny mirror)
- Refraction: light bends when it changes medium (gas to liquid produces rainbows)
Play this Lights Quizizz to test your knowledge!
Characteristics of Objects
Characteristics of Objects
Opaque
Opaque
Opaque objects allow NO light to pass through them and therefore, we can't see through them at all. An example is a plank of wood.
Translucent
Translucent
Translucent objects allow SOME light to pass through them and therefore, we can partially see through them. An example is a frosted window.
Transparent
Transparent
Transparent objects allow ALL light to pass through them and therefore, we can see clearly through them. An example is a clear window.
Characteristics of Sound
Characteristics of Sound
Sound is the vibration of air particles and in collisions, sound is created when air is heated. Sound has 2 main characteristics which are important to life (and to music!)
Sound is the vibration of air particles and in collisions, sound is created when air is heated. Sound has 2 main characteristics which are important to life (and to music!)
- Pitch (also known as frequency): how fast the sound wave is vibrating
- Volume: how big a sound wave is (how loud)
Laws of Force and Motion
Laws of Force and Motion
Each force acts on one object and it has both a strength and a direction.
Each force acts on one object and it has both a strength and a direction.
Each force has a counterpart that balances it out. Forces that are not counterbalanced are known as unbalanced forces and these forces lead to speeding up or changing direction.
Each force has a counterpart that balances it out. Forces that are not counterbalanced are known as unbalanced forces and these forces lead to speeding up or changing direction.
Interactions between Forces
Interactions between Forces
Objects that touch each others (wheels on a road) exert forces on each other like friction or push/pulls.
Objects that touch each others (wheels on a road) exert forces on each other like friction or push/pulls.
Gravity is the pulling force of the Earth on all objects in close distance to it. Gravity is why things on Earth fall to the ground while astronauts in space float. Forces decrease in size when they are further apart.
Gravity is the pulling force of the Earth on all objects in close distance to it. Gravity is why things on Earth fall to the ground while astronauts in space float. Forces decrease in size when they are further apart.
When objects collide, the contact forces transfer energy that change the motion of the objects.
When objects collide, the contact forces transfer energy that change the motion of the objects.
Different Types of Simple Machines
Different Types of Simple Machines
Play this Simple Machines game to understand the machines in our world -->
Play this Simple Machines game to understand the machines in our world -->
