Is the person on the sidewalk moving in relation to the passing bus?

Mechanical movement is a change in the position of the body relative to other bodies. The body we are looking at changes its position the body we are watching is called the reference point.
In our example, the reference point will be the bus. The position of a person relative to the bus changes, the person first approaches the bus, and then moves away from it. The person is moving relative to the bus.