Newton's Second Law (including inertia)
I can explain what the equation F = m × a means and use it to carry out calculations.
Newton's Second Law (including inertia)
I can explain what the equation F = m × a means and use it to carry out calculations.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- Resultant force = mass × acceleration, F = m × a.
- An object that is thrown in the air experiences a constant gravitational force towards the centre of the Earth.
- An object that is thrown in the air is constantly accelerating towards the centre of the Earth.
- Inertial mass is a measure of how hard it is to change the velocity of an object.
- Inertial mass = force ÷ acceleration, m = F ÷ a.
Keywords
Resultant force - The overall effect of the forces acting on an object.
Acceleration - Caused by a resultant force and results in a change in speed and/or direction of movement.
Mass - The amount of matter in an object, measured in kilograms (kg).
Inertial mass - The mass determined by Newton’s Second Law of Motion; m = F ÷ a.
Common misconception
When applying the equation F = m × a, pupils may take F to be any one of the forces acting on the object, rather than specifically the resultant force.
Provide some more complex examples, in which forces act in opposite directions, so pupils are required to work out the resultant force in preparation for completing calculations.
To help you plan your year 11 physics lesson on: Newton's Second Law (including inertia), download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 11 physics lesson on: Newton's Second Law (including inertia), download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 4 physics lessons from the Forces make things change unit, dive into the full secondary physics curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions
mass -
kilograms
displacement -
metres
velocity -
metres per second
acceleration -
metres per second squared
force -
newtons

Exit quiz
6 Questions
resultant force -
The overall effect of the forces acting on an object.
acceleration -
A change in velocity caused by a resultant force.
inertial mass -
The mass of an object based on how it accelerates when a force acts.