Question

Gravity on the moon is about one-sixth of gravity on Earth. An astronaut standing on a tower 20 feet above the moon's surface throws a ball upward with a velocity of 30 feet per second. The height of the ball at any time t (in seconds) is h(t) = -2.67t squared + 30t + 20. To the nearest tenth of a second, how long will it take for the ball to hit the ground.

Answer 1

h(t) will be zero at the ground

0=-2.67t^2+30t+20

Use the quadratic equation.

Answer 2

10.83 seconds