Mathguru tells me this is where physics questions go, so I'll post my question here.

I am having trouble understanding acceleration. Namely, how to calculate how fast an object will get to...

So here is my made up question to help me understand. Let's say (for simplicity) that gravity is equal to 10m/s^2 instead of 9.8. Now if we drop an object from 100 meters up how long (excluding air resistance) will it take to reach the ground?