A stone falls freely for 3 seconds — from what height does it fall, and at what speed does it land?

Step-by-step solution

1. 1

   Step 1. Free fall is a special case

   This is uniformly accelerated motion with $a = g = 10\ \text{m/s}^2$ and $v_0 = 0$. Height: $h = \dfrac{g t^2}{2}$, speed: $v = g t$.

2. 2

   Step 2. The height

   $h = \dfrac{10 \cdot 3^2}{2} = \dfrac{10\cdot 9}{2} = 45$ m.