# Falling Objects Problem for Calculus

## Homework Statement

The multiflash photograph in Figure A shows two balls falling from rest. The vertical rulers are marked in centimeters. Use the equation s=490t^2 (the free-fall equation for s in centimeters and t in seconds) to answer the following questions:
a) How long did it take the balls to fall the first 160 cm? What was their average velocity for the period?

## The Attempt at a Solution

160cm=490t^2
square root of (160/490)
My question is how do you find the average velocity? Do you take the derivative of the first equation which would be 490t and plug 160 cm in again?

Firstly, the derivative of $$s(t) = 490t^{2}$$ will not be 490t.