Unit 3 Summary

In Unit 3 we learned about three major concepts. They are Newton's Third Law, Universal Gravitational Force, and tides. Throughout this unit my logic was challenged and things that I previously viewed as easy to understand were proved far more complex than I thought. First off I will start with describing Newton’s Third Law and how it is present everywhere in the real world. This law states that whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. So, this creates action-reaction pairs, which can be written as simple as, Dorian pushes on wall and wall pushes on Dorian. Anytime an object exerts force on another object, the other object will exert the same amount of force. Before unit 3, I believed that in order to win a game of tug-of-war one side must pull harder than the other. However, this is not true because no matter how hard one-team pulls the other team will pull with the same amount of force (Newton’s Third Law). To win a game of tug-of-war one team must use the ground as an outside force, so the team who pushes on the ground harder will win. Next up is The Universal Law of Gravity, which states that everything pulls on everything else in a way that involves only mass and distance. This law can be written as F=Gmass1xmass2/distance squared. The G in the equation is the universal gravitational constant, which equals 6.67x10 to the power of 11. When you double the distance you decrease the force by the one fourth, which is called the inverse squared law. The equation always follows this pattern. When someone thinks of tides they usually think that tides are caused by the moon’s force on the Earth. This is partly true, but the actual cause of tides is the difference in force on each side of the Earth. This is caused by the difference in distances form the moon that each side of the earth has. Thus, creating a tidal bulge that has a high tide on opposite sides and low tide on opposite sides.  In this diagram A and C are experiencing high tides and the other sides are experiencing low tides. Also, the vector arrows show the difference in force from side C to side A.

  

 There are two specific types of tides that we learned about. The first is spring tides, which occur when the moon, earth, and sun are aligned creating a full or new moon. At this time the high tides are higher than usual and the low tides are lower than usual. The next is neap tides, which occur when the sun is at a ninety-degree angle to the earth, creating lower than usual high tides and higher than usual low tides.

          It is very difficult, at first to fully understand the fact that no matter how hard you push on an object that object will push back on you with the same amount of force. This totally goes against what I perceived as logical. This unit actually helped me improve my math skills, because while using the Universal Gravitational Law. Not being able to use a calculator taught me how to solve equations with exponents in a much simpler way than I had previously been doing. With the knowledge I have gained from this unit, I will be able to go to the beach and try to predict what tide is about to happen and whether it will be higher or lower than usual.