Question

A student drops a ball off the top of building and records that the ball takes 3.82s to reach the ground. Determine all unknowns and answer the following questions. Neglect drag.
What was the ball's speed just before striking the ground?

m/s

From what height was the ball dropped?

m

Answer 1

Explanation:

Given parameters:

Time of drop  = 3.82s

Unknown:

Final velocity of the ball  = ?

Height of fall  = ?

Solution:

To solve this problem, we apply the appropriate motion equation.

  To find the final velocity;

   v  = u + gt

v is the unknown final velocity

u is the initial velocity  = 0m/s

g is the acceleration due to gravity  = 9.8m/s²

t is the time

 v  = 0  + 9.8 x 3.82  = 37.4m/s

Height of drop;

       H  = ut + $\frac{1}{2}$gt²  

So;

        H  = (0 x 3.82) + ( $\frac{1}{2}$ x 9.8 x 3.82²) = 71.5m