Question

How much time does it take for the bill to fall beyond her grasp? the length of a bill is 16 cm?

Answer 1

Answer : t = 0.17 sec

Explanation :

It is given that :

length of a bill is, $l=16\ cm=0.16\ m$

from second equation of motion:

$s=ut+\dfrac{1}{2}at^2$

Where u is the initial velocity

Here, $u=0$

$s=\dfrac{1}{2}at^2$

$t=\sqrt{\dfrac{2s}{g}}$

$t=\sqrt{\dfrac{2\times 0.16\ m}{9.8\ m/s^2}}$

$t=\sqrt{\dfrac{0.3}{9.8}}$

$t=0.17\ s$

0.17 s it will take for the bill to fall beyond her grasp

Answer 2

Distance = 0.5 x g x t^2 where g is the gravitational force and t is the time required to cover the mentioned distance.

we have g = 9.8 m/sec^2 and distance = 16 cm = 0.16 m

From the above mentioned equation:
t = (2s / g)^0.5

Substituting with the givens, we can calculate t as follows:
t = [(2 x 0.16) / 9.8]^0.5 = 0.1807 seconds