What is Uniform Acceleration?
The rate of change of velocity over time. It tells us how quickly an object speeds up, slows down, or changes direction.
When we talk about motion, we often describe how fast something is going (its speed or velocity). But in many real situations, objects don't travel at a constant speed — they speed up or slow down. This change in velocity is called acceleration.
Acceleration that remains constant over time. The velocity of the object changes by the same amount every second.
If a car accelerates uniformly, it might gain exactly 5 m/s of speed every second. After 1 second it's going 5 m/s, after 2 seconds it's going 10 m/s, after 3 seconds it's going 15 m/s — a perfectly steady increase.
Think of an escalator that moves at a steady pace. Now imagine instead a magical escalator that moves faster and faster by the same extra amount each second — that's uniform acceleration in action!
The SI unit of acceleration is metres per second squared (m/s²). This might look confusing at first, but it simply means "metres per second, per second" — how many m/s of speed are gained (or lost) each second.
Key Definitions: Speed, Velocity, and Acceleration
Before diving deeper into uniform acceleration, it's essential to distinguish between some closely related terms.
A scalar quantity that describes how fast an object is moving, without any reference to direction. Measured in m/s.
A vector quantity that describes both how fast an object is moving and the direction of motion. Measured in m/s.
A negative acceleration — when an object slows down. The acceleration is in the opposite direction to the velocity.
Since acceleration is the rate of change of velocity, it is also a vector quantity — it has both magnitude and direction.
Do not confuse speed and velocity! A car going around a roundabout at a constant speed is still accelerating because its direction (and therefore velocity) is constantly changing. In MYP assessments, using these terms interchangeably will cost you marks.
The formula connecting these quantities is:
Where:
- = acceleration (m/s²)
- = final velocity (m/s)
- = initial velocity (m/s)
- = time taken (s)
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