Jen+Hughes+3-18

March 18, 2009 Today was another exciting day in Mr. Manning’s physics class. After a long week of PSSA assessment testing, and even though it was a shortened period, juniors were glad to finally be getting back to their favorite class. So, we started out the class with some quick demonstrations for the juniors. They were the same demonstrations that seniors saw yesterday. A person stood on a rotating table holding weights. The demo showed that when the person rotated, they slowed down when they held out their arms, thus putting all the weight on the outside of the circle, and sped up when they brought the weights to the chest, bringing all the weight to the central point. We also passed around a bicycle wheel. This demo showed that when the wheel rotated, the person holding the wheel can feel a significant amount of torque, or a twisting feeling. The last demo showed that when a person stood the rotating table (from the first demo) and held the rotating bicycle wheel, they would actually spin in the direction of the motion of the wheel. Amazing!! Mr. Manning then put a series of questions up on the smart board for the students to answer with the help of the person witting next to them. Some of the questions included the following: Students discussed all the questions in class and learned how leverage can be very important to our everyday lives. Next, students discussed the concept of the “center of mass” in an object. Mr. Manning explained that this point is where every side of the point has an equal amount of mass or all the mass is equally distributed. Every mass has this point. Some examples are shown in the pictures below. During rotation, all of the objects mass turn around this point. Class quickly came to an end because we had a shortened period. Students are reminded that the Physics Olympics are on April 7th at Solanco High School at 4 in the afternoon. A new extra credit opportunity is also now available to students. If students bring in two oddly shaped objects with a center of mass, they will receive extra credit. The objects can be made out of any material, including cardboard, wood, etc. Also, due to the significant amount of absent juniors because of those annoying PSSA tests, as well as our short period today, the due date for the homework (supposed to be due today) has been extended to tomorrow. So any student who has not completed problems on pages eleven through thirteen should do so by tomorrow.
 * At what point is it easiest to open a door? Right next to the hinge? In the middle? Of at a point furthest from the hinge?
 * It is easiest to open a door with the door knob furthest from the hinge because at this point the person pushing on the door has a greater amount of leverage on the door.
 * How could you modify a wrench if you are unable to loosen a bolt?
 * You could extend the handle of the wrench so you have greater leverage on the bolt. Or, you could add weight to the end of the handle.
 * Can any person bend a steel rod? How?
 * Any one could bend a steal rod if they have enough leverage. The longer the steel rod, the easier it will be for the person to manipulate the metal because they have a greater amount of leverage.