1. The problem statement, all variables and given/known data Okay, I've been set a piece of coursework to compare the reaction times of catching a ruler, with, or without a certain variable. (I've chosen either eye.) I'm having trouble working out the exact amount of time it takes the person to catch the ruler. (Yeah, I have attempted it. :) ) 2. Relevant equations (Explained in section 3.) 3. The attempt at a solution The ruler weighs 0.025kg. I hold the ruler at 1.04m. (An average of 10 times holding the ruler at a neutral position) To calculate the gravitational potential energy I do: 0.025 x 1.04 x 10 This gives me = 0.26 (Joules) The ruler falls 12 cm, (the person caught it at 18cm) So 0.025 x 0.12 x 10 = the kinetic energy = 0.03 The formula for speed is : Speed squared = kinetic energy/(0.5 times the weight) 0.03 divided by 0.0125 = 2.4 The square root of 2.4 = 1.549193338 To two decimal places = 1.55m/s And if the ruler travelled 12 cm at 1.55m/s 0.12/1.55 = 0.0774 seconds…… I must have gone wrong somewhere...because I swear its 'physically' (pun intended) impossible for them to catch it that quickly?