Question

If Chris jumps into a pool from a platform, his height above the water is given by the equation h(t) = -16t^2 + 21t + 20 where h(t) is the height in feet he is above the water at t seconds. Approximately, how long does it take Chris to hit the water (in seconds)?

a) 1.33 seconds
b) 1.57 seconds
c) 2.16 seconds
d) 1.95 seconds

Answer 1

Chris takes approximately 1.95 seconds to hit the water.

Step-by-step explanation:

To find the time it takes for Chris to hit the water, we need to determine when his height above the water, represented by the function h(t) = -16t^2 + 21t + 20, equals zero. This happens when the equation -16t^2 + 21t + 20 = 0. We can use the quadratic formula to solve for t, which gives us two solutions: t = 1.95 seconds and t = -0.81 seconds. Since time cannot be negative in this context, the approximate time it takes for Chris to hit the water is 1.95 seconds.