Physics question help plz!!!?

Question

Have a friend hold a ruler by one end, letting the other end hang down vertically. At the lower end, hold your thumb and index finger on either side of the ruler, ready to grip it. Have your friend release the ruler without warning. Catch it as quickly as you can. If you catch the ruler 6.8 cm (~2.7 inches) from the lower end, what is your reaction time?

Answer 1

h=0.5 g t^2

h = distance (in meters) from the lower end to where it was caught

then

t = sqrt( 2 h/g)

t=sqrt( 2 x 68 E-3 / 9.81 )=.12 sec