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.

Newton's second law of motion can be described by this equation:

Force = mass × acceleration

This is when:

- force is measured in newtons (N)
- mass is measured in kilograms (kg)
- acceleration is measured in metres per second squared (m/s²)

The equation shows that the acceleration of an object is:

- proportional to the resultant force on the object
- inversely proportional to the mass of the object

In other words, the acceleration of an object increases if the resultant force on it increases, and decreases if the mass of the object increases.

Calculate the force needed to accelerate a 22 kg cheetah at 15 m/s^{2}.

Force = mass × acceleration

Force = 22 × 15

Force = 330 N

- Question
Calculate the force needed to accelerate a 15 kg gazelle at 10 m/s

^{2}.Force = mass × acceleration

Force = 15 × 10

Force = 150 N