Question 45
HA student measures her reaction time using a ruler.
Her partner holds a ruler vertically, with the zero mark level with the top of the student's thumb. The partner releases the ruler without warning and the student catches it.
The Figure shows the ruler just after it is caught.
Figure
The ruler accelerates from rest at 10 m/s2.
a.[1]
Give the distance the ruler falls, in metres.
b.[3]
Calculate the speed of the ruler when it is caught.
Use the equation
v2−u2=2×a×xv^2 - u^2 = 2 \times a \times xv2−u2=2×a×x
c.[2]
Calculate the reaction time of the student.
d.[3]
The student repeats the test while talking on a phone. The ruler falls 45 cm before she catches it.
Show that her reaction time increases by 50%.
2.5 Stopping and braking distances Questions
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.