Newtons Laws Of Motion Explained (gcse)

Newton`s laws of motion can be confusing, but they`re fundamental to understand and score full marks on lots of questions, so what are they and what do they mean?

Newton`s First Law: Any object will remain at rest, or at uniform motion, unless an external force acts on it.

What does this actually mean? Firstly, uniform motion means a constant speed, (in other words, no acceleration).

An external force is any force that would be applied on the object, such as a driving force by the engine, a braking force from the brakes, or air resistance.

However, A VERY IMPORTANT NOTE is that if the forces on the object cancel out (i.e, the resultant force is 0), then the object will remain at uniform motion

Another way of writing the first law so it`s easier to understand can be:

Any object will remain at rest or constant speed (and have 0 acceleration), unless there is a resultant force acting on it.

This law is used both for theory and calculation questions in an even mix

Newtons second law: F = ma

This is an equation that is fundamental to how the world works.

F is the RESULTANT force in newtons

m is the mass is kilograms

a is the acceleration in m/s/s, or m/s2 or ms^-2

Keep in mind that there might be several forces going in the same or opposing directions. Therefore, F would be the sum or the difference between the forces

This law is mostly used for calculation questions

Newtons third law: For any action (force), there is an equal and opposite reactionary force.

There isn`t much else to explain with this force, but it is important as it explains why we don`t just sink into the earth. We exert a downwards force as our weight onto the earth (this is the action), so the earth provides an upwards (opposite directions) force (reaction) that is as strong as (equal) to our downwards force. Therefore, the resultant force is 0 as the forces are balanced, so we stay standing on the earth.

This law is mostly used for theory questions

That`s all of Newton`s laws of motion with GCSE physics, hope this helps! If you have any questions (about this article or any other questions) please don`t hesitate to message me!! Good luck with your studies!