Speed, Distance, Time Triangle

Trick / Shortcut

Topic

Formulas

How It Works

The relationship between Distance (D), Speed (S), and Time (T) can be visualized using a triangle. Imagine D at the top, and S and T side-by-side at the bottom.

To find any variable, cover it in the triangle to reveal the formula:

To find Distance (D): $D = S \times T$ (Speed × Time)
To find Speed (S): $S = \frac{D}{T}$ (Distance ÷ Time)
To find Time (T): $T = \frac{D}{S}$ (Distance ÷ Speed)

Unit Conversion Tip

To convert km/h to m/s: Multiply by $\frac{5}{18}$. (Since $1 \text{ km} = 1000 \text{ m}$ and $1 \text{ hour} = 3600 \text{ s}$, $1 \text{ km/h} = \frac{1000}{3600} \text{ m/s} = \frac{5}{18} \text{ m/s}$)
To convert m/s to km/h: Multiply by $\frac{18}{5}$.

Example

A train 360 m long travels at 72 km/h. How long does it take to pass a pole?

First, convert speed: $72 \text{ km/h} \times \frac{5}{18} = 20 \text{ m/s}$

Then, calculate time: $T = \frac{D}{S} = \frac{360 \text{ m}}{20 \text{ m/s}} = \textbf{18 seconds}