Velocity and Acceleration

This lesson covers velocity, acceleration and velocity-time graphs as required by AQA GCSE Combined Science Trilogy (8464), section 6.5.2. These concepts build on the speed, distance and time work from the previous lesson and are essential for understanding Newton's laws and momentum.

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Velocity

Velocity is speed in a stated direction. It is a vector quantity.

$v = \frac{\text{displacement}}{t}$v=tdisplacement​

An object can move at constant speed but have a changing velocity — this happens whenever the direction changes (e.g. moving in a circle).

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Acceleration

Acceleration is the rate of change of velocity. It tells you how quickly an object is speeding up, slowing down, or changing direction.

$a = \frac{v - u}{t}$a=tv−u​

Where:

• a = acceleration (m/s²)

• v = final velocity (m/s)

• u = initial velocity (m/s)

• t = time (s)

• A positive acceleration means the object is speeding up (in the direction of motion).

• A negative acceleration (deceleration) means the object is slowing down.

Exam Tip (AQA 8464): The equation $a = (v - u) / t$a=(v−u)/t is on the AQA equation sheet, but you should practise rearranging it to find $v$v, $u$u or $t$t.