The reaction time will be equal to the time the ruler takes to fall by 6.4 cm . the ruler is falling with acceleration due to gravity which is equal to 9.8 m /s² S = ut + 1/2gt² s is distance of fall , u is initial velocity , t is time and g is acceleration due to gravity . 6.4 = 0 + 1/2 x 9.8 t² t = 1.14 s . So reaction time is 1.14 s .
