Question

question 12 of 17, step 1 of 3
a ball is dropped from the top of a building that is known to be 400 feet high. the formula for finding the height of the ball at any time is h = 400 - 16t², where t is measured in seconds.
step 1 of 3: how many seconds will it take for the ball to hit the ground?

Explanation:

Step1: Set height to 0

When the ball hits the ground, $h = 0$. So we set up the equation $0=400 - 16t^{2}$.

Step2: Rearrange the equation

Add $16t^{2}$ to both sides: $16t^{2}=400$.

Step3: Solve for t

Divide both sides by 16: $t^{2}=\frac{400}{16}=25$. Then take the square - root of both sides. Since $t\geq0$ (time cannot be negative in this context), $t = 5$.

Answer:

5