Speed

Speed measures how much the Distance changes, every second.

It’s not in any specific direction, so it’s a scalar quantity.

Example

• We cycle 18km in 1 hour, so our speed is:
  • 18km\div1h=18hmh^{-1}
• Or, if we walk 400m in 200s, our speed is:
  • 400m\div200s=2ms^{-1}

\text{speed}=\text{distance}\div\text{time}

s=vt

v=\frac st

Where:

• s is the distance, measured in metres, m
• v is the speed, measured in metres per second, ms^{-1} (m/s)
• t is the time, measured in seconds, s

This calculates average speed.

A van drives 200m in 10s. Calculate the speed.

• v=\frac st
• v=\frac{200}{10}=20
• Answer: 20ms^{-1}

A car drives 75m in 5s. Calculate the speed.

• v=\frac st
• v=\frac{75}{5}=15
• Answer: 15ms^{-1}

A bike drives 10m in 20s. Calculate the speed.

• v=\frac st
• v=\frac{10}{20}=0.5
• Answer: 0.5ms^{-1}

A truck drives 240m in 8s. Calculate the speed.

• v=\frac st
• v=\frac{240}{8}=30
• Answer: 30ms^{-1}

A car drives 300m in 12s. Calculate the speed.

• v=\frac st
• v=\frac{300}{12}=25
• Answer: 25ms^{-1}

A van drives 600m in 15s. Calculate the speed.

• v=\frac st
• v=\frac{600}{15}=40
• Answer: 40ms^{-1}

A person cycles 100km in 4h. Calculate their average speed.

• v=\frac st
• v=\frac{100}{4}=25
• Answer: 25kmh^{-1}