Thursday, October 25, 2012

Unit 2 reflection


In this unit I learned about the physics of motion. Some of the key topics discussed during this unit were free fall, Newton’s second law of motion, projectile motion, and air resistance. We began the unit with Newton’s second law which states that forces is directly proportional to acceleration and mass is inversely proportional to acceleration. This definition is explained through the formula a=f/m. Furthermore, we learned about free fall. We learned that in free fall gravity is the only force acting upon a falling object. Therefore, all objects fall at the same acceleration of 9.8 m/s^2 . To calculate free fall, we were taught the equation, d=1/2gt^2. Transitioning from free fall, we learned about projectile motion. Projectile motion introduces both horizontal and vertical motion. Horizontal motion has a constant velocity and uses the equation, V=D/T. Vertical motion has constant acceleration and uses the formula d=1/2gt^2. The horizontal and vertical motions of a falling object create a parabolic path.  Finally, we learned about air resistance. With air resistance, we learned that as an object falls, air resistance increases with speed and decreases with acceleration until the object reaches terminal velocity. To calculate air resistance, you use the formula Fnet/M=A. Also, both weight and surface are affect air resistance. The more weight, the more air resistance is required since it has a greater downward force. The more surface area, the more air resistance because more air molecules are hitting the falling object and therefore a greater upward force is being applied to the object.  As a conclusion to the unit, we learned important applications of these physics resources. For instance, we learned about the fundamentals of air resistance through sky diving. As an example, a sky diver increases air resistance and speed until he reaches terminal velocity. When he pulls his parachute, he gains more surface area and thus a higher air resistance. Because there is more upward force acting upon the object, the sky diver slows down. Another example of physics in real life is baseball. Baseball shows us the application of projectile motion. When the ball is hit it forms a parabolic path. The horizontal velocity of ball remains the same as what the batter hit the ball with. The vertical velocity changes as decreases in velocity when it rises and then increases in velocity when it falls. To calculate the actual velocity which the ball is initially traveling you can use the formula a^2+b^2=c^2.

The most difficult challenge I faced this unit was retaining the information from the previous lessons and building on those previous lessons to learn new principles about physics. Specifically, the application of the formulas and the wording of my answers proved to be difficult for me.

I overcame these difficulties by practicing with the application and understanding the process of the formulas.  I will also force myself to be very specific when answering discussion questions as well as be very careful in my word choice.

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