Saturday, May 8, 2010

A Year of Physics


Wow! I believe that this is our last physics blog. Well, its been an interesting year and I have definitely learned a lot. For my last physics blog, I feel that it is fitting to return to my first post, where I told my impressions of the first four weeks of class. At that point I felt as though physics was a tightrope that I was struggling to balance on. This feeling lasted through the year, as physics is a fun, yet dificult subject.
In this blog, I am going to talk about something similar to a tight rope, a see-saw. When I was little an in Georgia I used to play on a big wooden sea-saw all the time. A see-saw is a great example of torque. Torque is measured by force times the cross product of the lever arm. This can be useful in figuring out where to sit on a see-saw to make it balanced with people of different weights. The lever arm of a see-saw is measured from the fulcrum where the weight of just the board can be balanced. In other words, if there are two people of the same weight they would need to sit the same distance from the fulcrum, but on opposite sides. If one person weighs twice the other, the lighter person needs to sit twice as far from the fulcrum as the other.

Saturday, May 1, 2010

Hard work...or is it?


Last weekend was the OBDA Select Stage Band concert in Seto Hall. I played the Bari Sax in this band and as usual got tired while caring my saxophone all around campus, band room to Seto Hall and back. My saxophone in its case is pretty heavy, but sadly, as I have learned from physics I do not do any work while I carry it, no matter how heavy it is, how long I carry it, or how tired I get.
Work is force x distance but since when I carry my saxophone I am applying force in an upward direction while I am walking forward, the force and distance vectors are perpendicular and so no work is being done.
I do however do a small amount of work while moving my saxophone and interestingly enough, the more times I stop and rest, the more work I do. Why? Because when I pick-up my saxophone I am in fact doing work, even though I am not while walking. When I lift my saxophone I am applying an upward force of the mass times the acceleration of my saxophone, and because it is also moving a distance in the same direction (upwards) work is being done as calculated by equation Work=force times displacement.
Also, when I am standing still with my saxophone it has potential energy of mass times g times the height at which I am holding the case.
(Sorry I do not have my actual saxophone to take a picture of, but this painting gives the general idea)