Fun with Gravity

Gravity can really bring
you down........

What goes up must come down. We discover gravity at an early age. I think the whole gravity concept sinks into our heads as babies. My kids discovered gravity when learning to walk and eating in their highchairs. Lots of “baby fall down and go boom” and constant splats of food hitting the kitchen floor resulted in a mental idea of a force out there that makes things fall.

At the age of 19 I rediscovered gravity. I was taking my first college physics class and getting refreshed on all sorts of fun formulas and calculations that I had learned in high school. I lived in a 12 story apartment my first sophomore year of college. The cool thing about this 12 story apartment was that it had a 12 story trash chute. My roommates and I had a good time dropping things like light bulbs, beer bottles, and rotten fruit from the twelfth floor to hear what kind of sound it made when hitting the bottom of the chute. One night one of my roommates reappeared from a trip to the grocery where he had bought a gallon sized glass jug of apple juice. We just couldn’t let that opportunity to apply some physics to the good old trash chute pass us by.

Once the jug was empty we filled it with water and waited for the prime drop opportunity, i.e. the time when the trash chute was completely empty. A few days later the chute was primed for dropping breakable stuff.  Half of us went to the twelfth floor and the rest went to the sixth.  I was on the sixth floor with the chute door open to watch the jug as it whizzed by. I gave the all clear and the jug was dropped. The jug was released, and just under three seconds later it hit rock bottom. I could barely see it as it passed the sixth floor trash shoot door. At the point of impact there was a loud BOOM! A mist of water shot up the chute well past the sixth floor. At that point we ran like hell, laughing hysterically.  We went back and did some calculations. At the sixth floor the jug had exceed 42 miles per hour and was cruising at just under 60 miles per hour at the time it hit the bottom. If you’ve ever had to pull over along a busy highway and get out of your car you’ve realized exactly how fast things fly by you at 60 miles per hour.

Now, at the time we didn’t realize what damage had occurred. At the point of impact the force was so high that it blew the trapdoor off the chute and knocked it into the dumpster. Apparently the jug was pulverized into small glass granules. Gravity gives us a lot of fits, make us fall down, makes things saggy, etc., but definitely provides the opportunity for many entertaining experiments. You don’t need to buy expensive things to entertain yourself. All you really need is some junk and a really high place to drop it from.