11-12


 * November 12, 2008-** Today's agenda for Physics included submitting a homework problem, reviewing our homework, doing a daily question and discuing Free Body Diagrams.


 * Homework Review:** At the beginning of class Mr. Manning had us write down our answer to problem number 4 in our homework. After submitting the problem we reviewed all of the answers. The answers to Newton's 2nd Law, Mass and Weight are as follows:

b.) 410N = mass x 9.8 mass= **42kg** a.) **597N** b.) **1396 N** c.) **225 N** d.) **97 N** b.) **20 kg** c.) Weight= 20 kg x -9.8 m/s/s = **-196 N** d.) Weight= 20 kg x -3.72 m/s/s = **-74.4 N**
 * 1) 1.) Weight= 2kg x 9.8 + 0 = 19.6 = **20N**
 * 2) 2.) a.) **410 N**
 * 1) 3.) For this problem everyones answers will vary depending on their weight. The following answers are based on my weight.
 * 1) 4.) a.) **20 kg**

The class came up with the following reasons why the rocket becomes easier to accelerate: Gravity is not acting against it because you are getting further away from planets. A second reason was that once the rocket was out of the earths atmosphere, there would be no fiction acting on the rocket. Thirdly, with the help of Mr.Manning, we were able to figure out that the mass of the rocket would decrease as the rocket used its fuel causing the rocket to be easier to accelerate.
 * Daily Question:** A rocket becomes progressively easier to accelerate as it travels through space. Why is this so?

__Normal Force (Fn):__ forces acting on an object from the environment. The arrow is drawn from the point of contact through the object, perpendicularly to the object's surface. __Static Friction Force (Fs):__ the force acting on an object that is not moving due to friction. The arrows start at the point of contact and drawn oposite the way the object would slide. (Static friction force will always be greater then Kinetic friction force) __Kinetic Friction Force (Fk):__ the force when the object is actually moved by an environmental force. This occures when something is moving against friction. The arrows are drawn the same way as Static Friction Forces. __Tension Force (Ft):__ the force when something in the environment pulls on the object. (Example: Spring Scale) The arrows are drawn where contact is made on the object, pointing in the direction of the environment. __Gravitational Force (Fg):__ the force on the object due to gravity. The arrows are drawn from the center of the object to the center of the earth. __Buoyant Force (Fb):__ the force of a fluid acting in the opposite direction of the Gravitational Force. The arrows are drawn from the bottom of the object upward. For example today Mr. Manning did an expirement with a 10N block (outside of water). When he put the block in the water the spring scale read that the block was 9N. This happened due to the upward force (Fb), which caused the net force to be a little less.
 * Free Body Diagrams (FBD) :** We then reviewed FBD's which are drawings of an object showing all forces acting on an object.

Here are drawing to help you better understand each force:


 * Homework:** Tonights homework, which is due Thursday November 13th is to complete the Free Body Diagrams for problems #1-10 in the FBD packet.


 * Sweet Dreams of Physics!**