year 7 science forces. what is a force? a force is a push or a pull. d i f f e r e n t types of...
TRANSCRIPT
Year 7 Science
Forces
What is a Force?A force is a push or a pull.Different types of forces can act
on a object at the same time.Forces can act in different
directions.An object can change speed or
direction only when the forces acting on it are unbalanced.
Action forces in one direction cause reaction forces in the other direction.
Different types of forces can act on an object at the same time and in different directions…
• Objects speed up/slow down when the forces are balanced or unbalanced?
ForcesA force cannot be seen! It has no
shape, colour or smellThey are interactions between
objectsThe effects of forces can be seen
If an object is speeding up, slowing down or changing direction there are unbalanced forces acting on it!
Sir Isaac Newton (1642-1727)
Millions saw the apple fall, but Newton asked why.
Measuring Forces
The units of force: the Newton (N)
1N is the equivalent of 98g weight
Or 1kg is 9.8N
ForcesForces
Represented by vectors (drawn as arrows)
This is a vector of size 20N to the 20N right
20N 20N to the left
5N 5N up
Forces
ForcesForces acting Resultant Force
20N
30N50N
20NNo resultant forceBALANCED forces
20N
60N 50N10N
This means that while forces are acting, they effectively ‘cancel’ each other out
Everyday ForcesWhat is a force?
◦A force is a push or a pull.Can you name any forces?
Gravitational
Friction Thrust DRAGMagnetic
Electrostatic
What forces are present?
Contact and Non-Contact Forces
Some forces are touching or contact forces.◦Physical push/pull◦Wind (air)◦Bouyancy (water)◦Friction
Some forces do not make contact and are non-contact forces.◦Gravitational forces◦Electrostatic forces◦Magnetic forces