1. Science Knowledge Organiser – Summer half term 1: Forces. Key concepts
Know the facts- Forces 1
Air resistance
A force of friction produced when an object moves through the air. 2
Balanced force
When the total force in opposite directions are equal in scale. 3
Contact force
Contact forces are forces that act between two objects that are physically touching each other 4
Non-contact force
Non-contact forces are forces that act between two objects that are not physically touching each other. E.g. Magnetic force 5
Deformation
Changing shape and/or size as a result of forces being applied. 6
Density
Density is a measurement that compares the amount of matter an object has in a given volume 7
Effort
Force used to move a load over a distance. 8
Elastic
Elastic materials return to their original shape and size after being stretched or squashed. 9
Extension
Increase in length, for example, as a result of being pulled. 10
Force
A push or a pull. The unit of force is the newton (N). 11
Friction
Force that resists one object moving through or over something. 12
Hooke's law
The extension of an object or material is directly proportional to the force applied. 13
Load
Force in a machine due to the mass, weight or movement of an object. 14
Mass
Mass is a measure of the amount of matter in an object. It is usually measured in g or kg 15
Moment
A turning effect of a force. Moment = Force x distance from pivot. 16
Newton
Unit of force named after British scientist Isaac Newton ( ), e.g. the frictional force on the boat is 20,000 N. 17
Newton's laws
If the forces add to zero there is no acceleration.
If the forces do not add to zero there is acceleration.
All forces come in pairs. 18
Action and reaction forces
Action force is force acting in one direction. Reaction force is force acting in the opposite direction. 19
Resultant force
The single force that could replace all the forces acting on an object, found by adding these together. If all the forces are balanced, the resultant force is zero. 20
Thrust
The force that pushes an object forward.
Know the facts- Forces 21
Upthrust
The force that pushes an object upwards in a liquid or a gas, also called buoyancy 22
Weight
The force acting on an object due to the pull of gravity from a massive object like a planet. The force acts towards the centre of the planet and is measured in Newtons (N).
Know the facts- drawing force diagrams 1
The Object
The object can be drawn as a dot 2
The arrows
The arrows must be touching the object 3
The size of arrows
The size of the arrows represent the size of the force. Larger arrow = larger force
Smaller arrow = smaller force
A force diagram for a car: this car will move to the right
Reaction force
Air resistance
Engine force
Gravity
Know the facts- Speed 1
Speed
The distance travelled in a fixed time period, usually one second 2
Acceleration
The rate of change in speed (or velocity) is measured in metres per second squared 3
Deceleration
Slowing down or negative acceleration 4
Distance-time graphs
A graph with distance travelled plotted on the vertical axis against time taken on the horizontal axis.
Know the facts- Electromagnetism 1
Magnetic
Able to be magnetised or attracted to a magnet 2
Magnetic field
Area surrounding a magnet that can exert a force on magnetic materials. 3
Electromagnet
A magnet made by wrapping a coil of wire around an iron bar and passing an electric current through the coil.