Understanding Displacement-Time Graphs
Ever wondered how to read movement from a graph? Displacement-time graphs tell you everything about an object's motion. When the line is horizontal, the object isn't moving (stationary). A straight diagonal line shows constant velocity, whilst a curved line indicates changing velocity or acceleration.
Here's the key bit: velocity equals the gradient of a displacement-time graph. This means you can work out how fast something's moving just by looking at the steepness of the line.
There's an important difference between average velocity and average speed. Average velocity considers your displacement from the starting point, whilst average speed looks at the total distance travelled. If you end up back where you started, your average velocity is zero, but your average speed isn't!
Quick Tip: Remember that velocity can be negative - it just means you're moving in the opposite direction to your chosen positive direction.
