Question

The observation deck of tall skyscraper 311 m above the street. Determine the time required for a penny to free fall from the deck to the street below. (Make x negative since the penny is falling)

Answer 1

8.0 s

Step-by-step explanation:

The penny is in free fall, so its motion is a uniform accelerated motion with constant acceleration; therefore we can use the following suvat equation:

`s=ut+(1)/(2)at^2`

where

s is the displacement

u = 0 is the initial velocity of the penny

t is the time

`a=g=-9.8 m/s^2` is the acceleration of gravity

The displacement is

s = -311 m

So we can re-arrange the equation to solve for t, the time of flight:

`t=\sqrt{(2s)/(g)}=\sqrt{(2(-311))/(-9.8)}=8.0 s`