Forces, accelerations and Newton's Laws of motion

Newtons first law

Newtons first law says that the velocity, speed or direction of an object will only change if a resultant force is acting on it.

This means that :

• If the resultant force on a stationary object is zero the object will remain stationary

• If the resultant force on a moving object is zero then it will continue to move at the same velocity in a straight line.

• If the resultant force on an object is not zero its velocity will change

Newtons second law

Acceleration is directly proportional to the resultant force of a object but inversely proportional to the mass of a object.

Resultant force = mass x acceleration

F=ma

The inertial mass is a measure of how difficult it is to change the velocity of a object

Inertial mass = force / acceleration

m = f/a

Newtons third law

It states that whenever two objects interact with eachother, they exert an equal and opposite force on eachother meaning forces always occur in pairs.