Question

A penny falls from a windowsill 25.0 m above the sidewalk. How fast is the penny moving when it strikes the ground?

Answer 1

Alright so this is a free-fall problem. You can use the equation vf^2 = vi^2 + 2ad to find the final velocity. Your givens are: d = 25m, and because it's freefall you know vi = 0 m/s and that vertical acceleration is -9.81 m/s^2. So, just plug in the values and solve for vf :)