of a moving object changes with time. These graphs also show if the object is moving at a constant speed or accelerating, decelerating, or still. Acceleration is shown by a straight rising line.

A horizontal line means the object is moving at a constant speed ... The area under the graph = the distance travelled. This is a speed-time graph for a car moving between two sets of traffic ...

The results have been consistently disappointing: the constants appeared to remain constant over time. But that still leaves open the possibility that the fundamental constants may be subtly ...