### Home > CALC > Chapter 2 > Lesson 2.3.2 > Problem 2-119

2-119.

What value of *h* represents the ground?

Velocity is slope of a distance/position graph. Since *h*(*t*) is a parabola, we do not have the skills (yet) to find the slope on a curve. But we can approximate.

Choose two times very close to *t* = 5. Use the function, *h*(*t*), to find the balloon's height at those times. Find the slope of the line that goes through those points. This will be a good approximation of the velocity of the balloon at *t* = 5.