A penny dropped into a wishing well reaches the bottom in 1.5 seconds. what was the velocity at impact?

At the surface of the Earth, the acceleration of all objects due to gravity

is about 9.8 m/s².

So an object that's acted on by no other forces except gravity increases

its speed by 9.8 m/s every second.

If the object is dropped from "rest" (zero speed), then after 1.5 seconds

have passed, it's falling at (1.5 x 9.8) = 14.7 m/s.

Its velocity is 14.7 m/s in the direction of straight down.