Tommy and Brendan go out into the woods, they come a clearing and see an abandoned well.

Tommy said 'I wonder how deep that well is?'

Brendan replied, 'There's one way we could figure it out'.

Tommy asked, 'What's that?'

Brendan suggested, 'We drop something down it, we time how long it takes to hit the bottom, you multiply that time 32 feet per second squared, the rate at which objects fall in a vacuum, subtract a little for wind resistance and we've got the depth of the well'.

Tommy asked, ' What are you going to drop down it?' 

Then Brendan looked all around and he saw this big heavy log lying on the ground.  Next he squats down by the log and, using his legs correctly, he gets it up onto his shoulders and staggers over to the edge of the well, tips it up, drops it into the well and they start to count, 'One hippopotamus, two hippopotamus, three .................... SPLASH!!!!

Tommy said, 'Three seconds!'

Brendan said, 'Quick, multiply that time 32 feet per second squared!'

Tommy, being a quick thinker said '288 feet. Subtract a little for wind resistance, let's say 18 feet. The depth of that well is 270 feet deep'.

As he finished the calculation Tommy shouted, 'LOOK OUT!!' and he pushed Brendan backwards and a goat ran between them and jumped head first down the well.

'My God, I've never seen anything like that' said Tommy.

Just then a farmer walks into the clearing and said, 'What's going on here boys?'

Brendan answered, 'We just figured out the depth of this well to be about 270 feet deep and then the strangest thing happened. A goat ran between the two of us and jumped head first down into the well.'

The farmer says, 'Thank heaven it wasn't one of my goats.'

 'How do you know it wasn't?' Tommy asked.

And the farmer says, 'Because all of my goats are tethered to big heavy logs.'