Question

A meter stick is held vertically above your hand, with the lower end between your thumb and first finger. On seeing the meter stick released, you grab it with these two fingers. You can calculate your reaction time from the distance the meter stick falls, read directly from the point where your fingers grabbed it. If the measured distance is 18.3 cm, what is the reaction time?

Answer 1

Answer:

$t=0.193s$

Explanation:

What is said is that the meter fell d=18.3cm=0.183m under the action of gravity. We can use the formula for accelerated motion:

$d=v_0t+\frac{at^2}{2}$

Since it departed from rest it will mean that:

$d=\frac{at^2}{2}$

So our time will be:

$t=\sqrt{\frac{2d}{a}}$

Which for our values is:

$t=\sqrt{\frac{2(0.183m)}{(9.81m/s^2)}}=0.193s$