Question

The function relating the height of an object off the ground to the time spent falling is a quadratic relationship. Travis drops a tennis ball from the top of an office building 90 meters tall. Three seconds later, the ball lands on the ground. After 2 seconds, how far is the ball off the ground?

30 meters
40 meters
50 meters
60 meters

Answer 1

When dropped, initial velocity is 0 so h(t) = 90 − k t^2. Since h(3) = 0, 90 − 9k = 0 → k = 10. Thus h(2) = 90 − 10·4 = 90 − 40 = 50 meters.

Answer: 50 meters.