# 1.5.3 Unbalanced Forces

### Forces & Motion

• When an unbalanced (resultant) force acts on an object, it can affect its motion in a number of ways:
• The object could speed up
• The object could slow down
• The object could change direction

A resultant force can cause an object to speed up, slow down or change direction

Extended Only

### Acceleration

• Force, mass and acceleration are related by the following equation:
`force = mass × acceleration`
`f = m × a`
• You can rearrange this equation with the help of the formula triangle:

• The greater the force, the greater the acceleration (for a given mass)
• For a given force, the smaller the mass the greater the acceleration

#### Exam Tip

If you are trying to find the acceleration check that you know both the unbalanced (resultant) force and the mass of the object. If you don’t, you might need to calculate the acceleration using a different equation.

### Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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