### What are some common units to measure speed?

Some common units to measure speed include:

- Miles per hour (mph): Miles per hour is a unit of speed commonly used in the United States and the United Kingdom. It measures how many miles an object or person travels in one hour.
- Kilometers per hour (km/h): Kilometers per hour is a unit of speed widely used around the world. It measures the distance traveled in kilometers in one hour.
- Meters per second (m/s): Meters per second is the unit of speed in the International System of Units (SI). It quantifies how many meters an object or person travels in one second.
- Feet per second (ft/s): Feet per second is a unit of speed commonly used in the United States. It represents the distance traveled in feet in one second.
- Knots: A knot is a unit of speed primarily used for measuring the speed of a vessel (such as a ship or aircraft) in navigation. It is equal to one nautical mile per hour.

These common speed units offer different ways to quantify how fast an object or person is moving, whether it's in everyday usage or specific contexts like aviation.