Question

One of the first astronauts who traveled to the moon hit a golf ball on the moon. Suppose that the height h in meters of a ball t seconds after it is hit is described by h = 0.8t2 + 10t. At what times is the ball at a height of 20 meters? The ball is at a height of 20 meters at seconds and at seconds.

Answer 1

Answer:v(t) = 24 − 1.6t = 0 ⇒ t =

24

1.6

= 15.

Step-by-step explanation:

velocity: v(t) = ds

dt = 24 − 1.6t (m/s).

acceleration: a(t) = dv

dt = −1.6 (m/s2

).

s(15) = 24 · 15 − 0.8(15)2 = 180.