Question

a student drops a rock from a bridge to the water 12.0m below. With what speed does the rock strike the water?

Answer 1

you have two formulas
\[v=at\] and \[s=\frac{ at ^{2} }{ 2 }\]
calculate the time from second formula \[12=\frac{ 9,8t ^{2} }{ 2 }\]
t=1,565 s
then use the first formula
\[v=at=9,8\times1,565=15,337 m/s\]