A century after Albert Einstein said we would never be able to observe the instantaneous velocity of tiny particles ... In 1907, Einstein likely did not foresee a time when dust-sized particles ...

Velocity-time graphs show how the velocity (or speed) of a moving object changes with time. These graphs also show if the object is moving at a constant speed or accelerating, decelerating ...

Save guides, add subjects and pick up where you left off with your BBC account. The gradient of a velocity-time graph at a particular time gives the acceleration of the object at that time.