Question

A penny falls from a windowsill which is 25.0 m above the sidewalk. How much time does a passerby on the sidewalk below have to move out of the way before the penny hits the ground?

Answer 1

\[h=u t+\frac{ 1 }{ 2 }g t^2\]
u=0
g=10 m/s
h=25 m
find t