Scientists often make measurements. The physical quantities they measure fall into two categories: scalars and vectors. Scalar and vector quantities are treated differently in calculations.

Speed and velocity refer to the motion of an object. Distance-time and velocity-time graphs can be a useful way of analysing motion.

Isaac Newton’s laws surrounding forces were formulated hundreds of years ago, but are still used today – they help to describe the relationship between a body and the forces that act upon it.

Momentum can be thought of as the product of mass and velocity. Momentum helps explain some of the most important interactions in nature.

Forces are responsible for changing the motion of object. If more than one force is present, the shape of an object can also be changed.

Gravity is one of the most important forces in the universe. An object with mass in a gravitational field experiences a force known as weight.