Acceleration (Oxford AQA IGCSE Combined Science Double Award)

Acceleration

What is acceleration?

• Acceleration is defined as the rate of change of velocity

• In other words, it describes how much an object's velocity changes every second

• Acceleration is a vector quantity, it has both magnitude and direction

• Any change in velocity is acceleration

• This includes:

  • Speeding up

  • Slowing down

  • Changing direction

• As it is a vector quantity, the sign of acceleration tells us its direction, depending on which direction is defined as positive

  • If an object is speeding up (accelerating), its acceleration has the same sign as its velocity

  • If an object is slowing down (decelerating), its acceleration has the opposite sign to its velocity

Acceleration & Deceleration

Calculating average acceleration

• Average acceleration can be calculated using:

• Where:

  • a = average acceleration measured in metres per second squared (m/s²)

  • Δv = change in velocity measured in metres per second

  • t = time measured in seconds (s)

• Change in velocity can be found using:

• Where:

  • Δv = change in velocity

  • v_f = final velocity

  • v_i = initial velocity