## Wednesday, January 27, 2010

### Reflection: Gravitational forces, Centripetal forces, and Circular motion

I learned a lot about circular motion, gravitation, and centripetal force. I learned that uniform circular motion is when the object is moving at a constant speed in a circle. The velocity is found by 2pi(r)/T. T is the period, or the time it takes for the object to complete one full revolution around the perimeter of the circle it is going in. When an object changes direction, it accelerates. So although the object may have a constant speed, it does not have  constant velocity (scalar vs. vector!). The velocity is tangential, and the acceleration of the velocity is called centripetal acceleration. This is found by the equation v^2/r. The acceleration is perpendicular to the velocity. The force that keeps the object going in a circle is called centripetal force. This force is found by using mv^2/r. There are also vertical circles. These circles are not much different, accept for at the top you subtract mg and when it is at the bottom you add mg. Universal Gravitation states that the force that pulls all other bodies and causes them to fall exists also between all other bodies. This force pulls down, but also things together. This helps things like the planets stay in orbit.

What I have found difficult is knowing what equation to use at what time; especially with the gravitational equations. I also find the FBD's difficult to draw, because the forces can be switched around. I also sometimes get confused what the system is. I am still getting the hang of gravitational forces, but i think i am getting better. Practice makes perfect.

I think that my problem solving skills are pretty good, but could definitely improve. I think that with the more problems that I see, I improve with each one. I sort of freak out when I glance at a problem and it seems too difficult. But when I actually look at it and focus I usually see a way to find the answer. I think my problem solving skills are definitely improving.