Question

How much times does it take for the first black/clear part to fall through the photo gate timer, starting from the rest? Plastic strip has 8 black stripes and 8 clear stripes the width of the black/clear pair is 5 cm.

Answer 1

I can figure out this is a frefall motion.

Starting from rest => Vo = 0

Then, use the equation: d = [1/2]gt^2 => t = √(2d/g)

d = width of a black/clear stripe pair = 5cm = 0.05m

g ≈ 10 m/s^2 (the real value is about 9.81 m/s^2)

t =√(2*0.05m/10m/s^2) =  0.1 s

Answer: approximately 0.1 s