Physics 4 Flashcards
What is a scalar?
A quantity that has size only
Scalars do not have direction.
What defines a vector?
A quantity that has size and direction
Vectors are represented with both magnitude and direction.
Define mass.
The amount of matter in an object
Mass is usually measured in kilograms.
Define weight.
The force acting on the object due to the pull of gravity
Weight is measured in newtons.
What does Hooke’s law state?
The extension of a spring is directly proportional to the force applied provided the limit of proportionality is not exceeded
This law applies to elastic materials.
What is the principle of moments?
When a body is in equilibrium, the sum of the clockwise moments will equal the sum of the anticlockwise moments about the pivot
This principle is used in mechanics to solve problems involving levers.
Define centre of gravity.
The point on an object where all of the weight may be considered to act
The centre of gravity can change based on the object’s shape and distribution of mass.
What is the principle of conservation of energy?
Energy can be changed from one form to another but the total amount of energy does not change
This principle is fundamental in physics and applies to all physical processes.
Define renewable energy resource.
Energy that will be replaced in less than a human lifetime and so will never run out
Examples include solar and wind energy.
Define non-renewable energy resource.
Energy that cannot be replaced in a human lifetime so will run out
Examples include fossil fuels like coal and oil.
What is efficiency?
The fraction of the total input energy that is transferred usefully
Efficiency is calculated using the formula: Efficiency = useful output energy/total input energy.
