### Home > APCALC > Chapter 5 > Lesson 5.2.3 > Problem 5-81

5-81.

If the height (in meters) of an object traveling vertically is represented by the function *h*(*t*) = −4.9*t*^{2} + 21*t* + 3 where *t* is measured in seconds, determine its: Homework Help ✎

Starting velocity

Evaluate

*v*(*t*) when*t*= 0.Starting position

Evaluate

*h*(*t*) when*t*= 0.Maximum height

Since the height function is a parabola, the maximum height can be determined by using Algebra to locate the vertex. Calculus can also be used.

The maximum height will occur at the time when

*v*(*t*) = 0.The vertex of the parabola is located at

*t*= –21/2(–4.9) ≈ 2.143 seconds.*h*(2.143) ≈ 25.5 m