Wonderful! Whether the figure is moving forward or backward, it is travelling only along one line. In the other cases, it is not travelling on a

**single straight line**.The simplest quantity that captures whether an object is moving or not is its

If an object's speed is \(0\), it is not moving. If an object's speed is not \(0\), it is moving. It's that simple!

**speed**. For example, if Johnny is riding his bike at 80 km/h, it means that, if he continued at that speed, he will cover 80 km in 1 hour.If an object's speed is \(0\), it is not moving. If an object's speed is not \(0\), it is moving. It's that simple!