Solve the problem.
-A rock falls from a tower that is 416 ft high. As it is falling, its height is given by the formula h = 416 - 16t2. How many seconds will it take for the rock to hit the ground (h=0)?
A) 5.1 s
B) 10,816 s
C) 20.4 s
D) 20 s

Question

Quizplus · Accepted Answer

To find the time it takes for the rock to hit the ground, set h = 0 and solve for t: 0 = 416 - 16t^2. Rearranging gives 16t^2 = 416, and dividing both sides by 16 gives t^2 = 26. Taking the square root of both sides gives t = √26, which is approximately 5.1 seconds.

Solve the Problem. -A Rock Falls from a Tower That Is 416 Ft