The Physics of a Lazy Susan

Here we go: So this is the first time I'm doing my journal before nine o'clock at night on Sunday. Wow! I can't believe it. Real fast, that BJ Penn fight was just a huge smashing. GSP had superior position the entire fight and just worked him. It was pretty sad. At least Lyoto Machida had a good fight. That guy is scary. Anyway, I went to my friend's house to watch the fight and there was a lot of food. I mean a lot. The best was the pokes from Tamura's and the barbeque chicken. Ono. After the fight we didn't know what to do, so we decided to shoot a film. It was pretty stupid. The idea was to do a survival show. I was the survivorman. We just went outside on the street and did random stuff. I ate an aloe. That was sick. The whole movie was pretty stupid. Anyway that explains the fake dirt spots on my face. While my friend was doing the editing, I went to get something to drink. On the way back, I noticed that they had a lazy susan on the dining room table. It was pretty cool. I started to play with it. I put the soda cans on top of the lazy susan and spun it around. While I was doing this I was reminded of a lab that we did. The lazy susan was exhibiting rotational dynamics. I ran to grab the camera and quickly captured it on film. Here is what happened.

When I spin the lazy susan I am exherting a torque on it. That is, I am creating a force that causes rotation. This sends the susan spinning. The cans on top of the susan are sent into motion as well. Because they are spinning, the cans have both angular momentum and centripetal accleration. The can in the middle of the lazy susan is tricky. The can has a greater centripetal acceleration than can on the outside, but it has less angular momentum. Of course this makes sense. The two cans have the same linear velocity and moment of inertia. The can toward the outside has a greater angular momentum. The radial distance from the center of rotation causes it to have a greater momentum becasue the moment of inertia of the two cans are the same. This works oppositely with centripetal acceleration. The can on the inside is closer to the axis of rotation so its angular acceleration is greater. Because the two cans have the same mass, the centripetal force on the inside can is also greater. Centripetal force is a force that causes circular motion. Centripetal force is expressed similarly to Newton's second law. Fc = m*Ac The centripetal force always points inward. The pepsi can toward the outside of the lazy susan flies off of the table because the centripetal force is not great enough to overcome the force of friction which opposes it. Notice the can flies off of the suzan tangent to its circular motion.The can in the middle has a greater centripetal force and thus stays on the suzan. So there it is, physics on a lazy susan. I hope you get to play with one. Its super fun. Ok gotta watch 'The Office'. SeeeeYa SuckaTrucka!!!