Physics Flashcards
Force
(Definition)
A push or pull on an object caused by it interacting with another object.
What does Force affect?
- Changes speed
- Changes direction
- Changes shape
Two types of Force
1) Contact Force
2) Non-contact Force
Examples of Contact Forces
Upthrust
Friction
Tension
Examples of Non-contact Forces
Weight
Electrostatic force
Magnetic force
Free-Body Diagram
(Definition)
A diagram that only shows only the object (not the surroundings) and the individual forces acting upon it
Rules of Free-Body Diagrams
1) The larger the force, the longer the force arrow.
Ideally, the length of the arrow should be proportional to he magnitude (size of the force).
2) Force arrows always start touching the object and point away from it.
3) The start of the force arrow should be where the force acts
E.g. Weight acts from the centre of mass. Friction acts from where the objects are in contact.
4) Force arrows should be labelled
E.g. Weight / tension / etc.
Accelerate
(PHYSICS Definition)
A change in speed, either faster OR slower
Resultant Force
(Definition)
The single force that would have the same effect as all the separate forces acting on an object.
It is the total sum of all the forces.
What happens when the resultant force is ZERO?
The object can either be STAITIONARY or moving at CONSTANT SPEED
* When an object is moving at a constant speed, there will be resistive forces, neutralising the resultant force to 0
* When an object is stationary there will be no resistive forces
What happens when there IS a resultant forces acting on an object?
The object will accelerate
Mass
The amount of matter an object is made of (kg)
Weight
The force acting on an object due to gravity (N)
How to calculate weight
Weight = mass x gravitational field strength
How to tell a quantity is DIRECTLY PROPORTIONAL
1) It’s results are in a straight line
2) It’s results passes through the origin
How to tell a quantity follows Hooke’s Law
The extension of the object is DIRECTLY PROPORTIONAL to the FORCE APPLIED
How to calculate force
Force (N) = spring constant (N/m) x extension (m)
F = ke
What will prove Hooke’s Law does not always work?
1) Any objects beyond the Limit of Proportionality
2) Elastic bands - as they do not go back to their original length after time
What will adding weight beyond the limit of proportionality do?
It will produce large extensions as the spring will become PERMANENTLY DEFORMED and not return to its original shape
What happens to an ELASTICALLY DEFORMED object?
It goes back to its original shape and length when the force is removed
What happens to an INELASTICALLY DEFORMED object?
It does not return to its original shape and length once the force is removed
Energy Stores
Chemical
Kinetic
Gravitational Potential
Elastic Potential
Thermal
Nuclear
Electrostatic
Magnetic
Energy Pathways
Electrical
Mechanical
Heating
Radiation
How to calculate power
Power = energy / time
