When has the rocket descended 500 centimeters?

Question

The height of a model rocket is given (in centimeters) by the formula h = −500t2, where t is measured in seconds and h = 0 refers to its original height at the top of a mountain. It begins to fly down from the mountain-top at time t = 0. When has the rocket descended 500 centimeters?

Answer 1

-500t² = -500 cm

divide by -500

to get: t² = 1 or t = 1 second

h(1) = -500 cm