A girl throws a stone straight down from a bridge. The stone leaves her hand with speed of 8.00 m/s at a height of 12 m above the water below. How much time does it take for the stone to hit the water?
A) 0.41 s
B) 17.3 s
C) 0.95 s
D) 1.8 s
E) 2.58 s

Question

Quizplus · Accepted Answer

To solve this, we use the equation of motion under gravity: $s = ut + \frac{1}{2}gt^2$, where $s$ is the distance (12 m), $u$ is the initial velocity (8 m/s), $g$ is the acceleration due to gravity (approximately 9.8 m/s$^2$), and $t$ is the time. Plugging in the values, we get $12 = 8t + \frac{1}{2} \times 9.8 \times t^2$. Solving this quadratic equation for $t$, we find that $t \approx 0.95$ seconds.

A Girl Throws a Stone Straight Down from a Bridge