Human reaction time is usually greater than 0.10 s. If your friend holds a ruler between your fingers and releases it without warning, how far can you expect the ruler to fall before you catch it?
A) at least 3.0 cm
B) at least 4.9 cm
C) at least 6.8 cm
D) at least 9.8 cm

Question

Quizplus · Accepted Answer

The ruler will fall for the duration of the reaction time. Using the average human reaction time of 0.10 s and the formula d = 1/2at^2, where a is acceleration due to gravity (9.81 m/s^2) and t is the reaction time (0.10 s), we find that the ruler will fall approximately 4.9 cm before you catch it.

Human Reaction Time Is Usually Greater Than 0