Speed, Distance & Time
Year 7 🚀 Forces & Motion Calculate speed using v = d/t; understand distance-time graphs.
🏃 The Speed Equation
Speed tells you how fast an object moves. It is the distance covered per unit time.
⚡ Speed Formula
$$v = \frac{d}{t}$$
$v$ = speed (m/s) · $d$ = distance (m) · $t$ = time (s)
Use the formula triangle: cover the quantity you want to find.
📈 Distance–Time Graphs
A distance–time (d-t) graph shows how far an object has travelled over time.
| Graph shape | Meaning |
|---|---|
| Horizontal line | Object is stationary |
| Straight line (slope) | Constant speed |
| Steeper slope | Faster speed |
| Curved line | Changing speed (acceleration/deceleration) |
Gradient = Speed
$$\text{speed} = \frac{\text{rise}}{\text{run}} = \frac{\Delta d}{\Delta t}$$⚡ Average vs Instantaneous Speed
Average speed is calculated over the whole journey. Instantaneous speed is the speed at a particular moment.
Example: A runner completes 400 m in 50 s.
Average speed = 400 ÷ 50 = 8 m/s
Average speed = 400 ÷ 50 = 8 m/s
Ready to test yourself? Click the Quiz tab above to answer questions on this topic!
🏃 Speed Calculator & Motion Graph
Motion Graph (s-t)