9-25-08

Fifth Period 9/25/08 Lindsey Chillot

When I walked into class today, there was a graded Daily Question. The question was: a) What happens when you jump heavily onto your feet from an elevated position? b) Can you think of a reason why you are a little taller in the morning than the night before?

Mr. Manning's daily schedule for today was: 1. Graded Daily Question 2. Finish the activity from yesterday 3. a discussion about yesterdays activity 4. maybe auto-control?

There were no assignments handed in today (except for the graded Daily Question).

Mr. Manning had us complete a state required survey on the laptops. Then, we finished the "Stretchin' for an Answer Activity" (pages 11-13) that we started yesterday involving pulling a cart of weights with a rubber band or spring. In order to stretch a rubber band or spring, an amount of force must be applied with our hands. If the rubber band or spring is stretched to a constant length, then we are applying a constant force. This activity applies to Newton's 1st Law (every particle remains in a state of rest or continues in a state of motion with constant speed in a straight line unless compelled by an unbalanced force to change that state). On the activity sheet, the first observation made was there will be an increasing force that causes the cart to move at an increasing speed. The second observation made was there is a constant force with a constant speed for the whole time. The least amount of force you need to keep the cart going at a constant speed was 1 newton. You have to apply some minimum force of about 0.7-1 newtons to get it just to move. A cart of weights being pulled by a rubber band (in this picture, Kyle Karpinski)

After the activity was completed, we received a notes worksheet entitled "Unbalanced Forces"( page 14). This is a summary of the lab/activity just completed. The more force you apply to an object, the more it will move. You know if you have constant speed, you have equal forces. When something moves across a surface, there is a resistance called friction. If the pulling force on an object is equal to the friction force, the object WILL NOT move. If the amount of pulling force is greater than the friction force, there WILL BE acceleration. Force is measured in Newtons (about 4 Newtons in a pound). Let's say where was 10 N of friction force, and 25 N of pulling force. You must subtract the numbers to find the pulling force which is 15 N (called a sum and written as a sigma). Sigma also means unbalanced force (meaning 1 force is larger than the other) and cause things to accelerate.


 * Homework: number 1 and 2 on the notes sheet.
 * Reminder-- the test and reading guide may be due on Wednesday?