Solve the problem.
-A rock falls from a tower that is 117.6 m high. As it is falling, its height is given by the formula $$h = 117.6 - 4.9 t ^ { 2 }$$ How many seconds will it take for the rock to hit the ground (h=0)?
A) 4.9 s
B) 10.6 s
C) 10.8 s
D) 2,800 s

Question

Quizplus · Accepted Answer

To find the time it takes for the rock to hit the ground, set $h = 0$ and solve for $t$: $0 = 117.6 - 4.9t^2$. Rearranging gives $4.9t^2 = 117.6$, and solving for $t$ gives $t = \sqrt{\frac{117.6}{4.9}}$, which simplifies to $t = 4.9$ seconds.

Solve the Problem h=117.6−4.9t2h = 117.6 - 4.9 t ^ { 2 }h=117.6−4.9t2

Solve the Problem $h = 117.6 - 4.9 t ^ { 2 }$