Last spring break, my parents and I flew up to Oregon to visit my brothers who are going to school there. We snowboarded as much as possible, so we were outside a lot and it was really cold. As you can see from the picture, my brothers and I wore several layers of cloths in order to stay warm (they would be horrified with this picture because they prefer to act hard-core and wear as little as possible as a sign that they are true 'oregonians' ) Anyway, most of they layers we wear under our outer jackets are fleece and when you are trying to peel off your outer layers after getting home, an electric charge is created. Usually, the fabric of our sweaters would be neutral, however, because the weather was very cold and there was very little moisture in the air, when we peel the fabrics away from each other quickly, a charge is created. Even though they are the same fabric, one steals electrons from the other, like we saw with the tape and the saran rap in lab 21. Charge is always conserved, so if one sweater becomes positive, the other becomes equally negative. The charge that is on the sweaters is not very much and to make the sweater become neutral again you just have to touch it and your body acts as a ground, effectively removing extra charge. 

Banked Turns for Bikes

This summer, my family and I went to California (same trip as the rope swing picture) and when my parents were done paddling we visited some colleges. These two pictures are of the campus as UC Davis. On the right, you can see that there are tons of bikes on campus and this picture was taken in the summer so classes weren't even in session, so during the regular year there would be even more. The picture on the right is a walkway/bike path that winds through campus and you can see that the path is banked as it curves down the hill. Banked curves allow for greater speeds, because on a banked curve centripetal force is made up of a combination of normal force and the x-direction component of friction. On level ground, centripetal force just comes from normal force, so on a banked curve, there is more centripetal force than on level ground. This added centripetal force allows bikers to travel at greater speeds without losing grip and flying off tangent to the curve. This banked path is especially important on a college campus because there are tons of bikers, all of whom are in a hurry and probably hyped up on caffeine :)