Word Problem

[cprochilo]

An object launched upward with an initial velocity of 9.8m/s from a height of 73.5m will have a height of s(t)=(-4.9t^2)+ 9.8t + 73.5m, where s is in meters and t is in seconds. How long will it take the object to hit the ground.

I recieved this homework problem and I can't figure out how to start it, I was wondering if anyone could at least get me on the right track. Thank you

 

[stapel]

Hint: What is the value of the "height" when the object hits the ground?

Eliz.

 

[soroban]

Re: Calculus Word Problem

Hello, cprochilo!

This isn't really a Calculus problem . . .

An object launched upward with an initial velocity of 9.8m/s from a height of 73.5m
will have a height of: \(\displaystyle \,s(t)\:=\:-4.9t^2\,+\, 9.8t\,+\,73.5\),
where \(\displaystyle s\) is in meters and \(\displaystyle t\) is in seconds.
How long will it take the object to hit the ground?

What is the object's height when it hits the ground?
\(\displaystyle \;\;\)Obviously, the height is 0 (zero).

Very well, when is the height equal to 0?

Let's find out: \(\displaystyle \,-4.9t^2\,+\,9.8t\,+\,73.5\:=\:0\) . . . solve for \(\displaystyle t\).

 

[cprochilo]

Thank you for your help