Question

A disc is thrown into the air with an upward velocity of 20 ft/sec. Its height h in feet after t seconds is given by the function h = -16t² + 20t + 6. How long does it take for the disc to be caught 3 feet off the ground

Answer 1

Time t = 1.39 seconds

Explanation:

Given;

Initial velocity v = 20 ft/sec

height equation;

h = -16t^2 + 20t + 6

How long does it take for the disc to be caught 3 feet off the ground;

At this point h = 3

Substituting h = 3 into the height equation;

3 = -16t^2 + 20t + 6

-16t^2 + 20t + 6 - 3 = 0

-16t^2 + 20t + 3 = 0

Solving the quadratic equation;

t = 1.39 or t = -0.14

Since t cannot be negative;

Time t = 1.39 seconds