The time t (in seconds) that it takes for an object to fall a distance of s feet is given by the formula

t = radical symbol s /4

In some places, the Grand Canyon is one mile (5,280 feet) deep. How long would it take a stone dropped over the edge of the canyon to hit bottom?

would the answer be

18 seconds?

2 answers

it is 26seconds
A falling object travels a distance given by the formula
d = 5t + 16t2,
where t is measured in seconds and d is measured in feet. How long will it take for the object to travel 21 ft?