A student catches a ruler after it is released without warning. What should the student measure to determine their reaction time using a conversion table?
the length of the ruler below the releasing hand
the distance between the thumb and finger initially
the distance the ruler falls before it is caught
the height of the releasing hand above the floor
126 exam-style questions on Edexcel GCSE Physics 2.5 Stopping and braking distances, covering 2.5.1 Stopping distance and reaction time, 2.5.2 Factors affecting stopping distance, 2.5.3 Dangers of large decelerations, and 2.5.4 Braking distance and initial speed. Each one has a worked solution and a mark scheme showing where the marks go.