Laws of Motion

Contact forces examples: friction, air resistance, tension, and normal reaction force (support).

Non-contact forces examples: - gravitational, electric (electrostatic), magnetic forces.

In Physics we have three fundamental Laws of Motion created by Sir Isaac Newton way back in the 17th century. Today we are looking at the first law of motion, sometimes called the law of inertia.

In this video, we are going to learn about and practice applying Newton’s Second Law in calculations, relating force, mass and acceleration.

• A force is a push or a pull that acts on an object.

• Forces are vector quantities because they have both magnitude and direction, and so can be represented by an arrow. Scalar quantities have only magnitude and no direction. 

• When several forces act on an object they can be replaced by a single force that has the same effect. This single force is called the resultant force.

In this video we will look at how force, mass, velocity and acceleration are all related. 

Remember that velocity is the speed in a particular direction - a vector quantity! To change the velocity of an object there needs to be a  force acting on it, and the object is accelerating. Find out different formulae we use for force, mass, velocity and acceleration in this video!

The third law of motion states that for every action there is an equal and opposite reaction.