I read two articles on this objective they were titled “Newton’s Laws and How They Apply to Astronomy” http://www.brighthub.com/science/space/articles/60286.aspx and “The Science: Orbital Mechanics” https://earthobservatory.nasa.gov/Features/OrbitsHistory/page2.php
“If Kepler’s laws define the motion of the planets, Newton’s laws define motion.” Is what the article first states about Newton. I could not have said it any better myself. The article explains how Newton would look back on Kepler’s laws only to realize that all motion whether it was planetary orbits or an “apple falling from a tree” follow the same rules when it comes to the order of nature. Newton in turn wrote “we must, as far as possible, assign the same causes.” Meaning that we should find the explanation as to why all things seem to follow these patterns. His ideas revolutionized Astronomy yet again since Kepler when he shifted perspective to working to find the bigger picture behind all “Unifying patterns of nature”. He did this by creating his three laws of motion.
Law 1 the law of inertia- “Every body perseveres in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed theron.”
Basically what this law is stating is that an object that is in motion will tend to stay in that motion unless acted upon by an outside force and that an object at rest will stay at rest unless acted upon by an unbalanced force. So if a car is driving down the road and you take your foot off of the gas pedal the car will continue to move forward unless you hit the brakes or let the car go till gravity and other forces outside the car slow it down to a stop.
Law 2 F=ma- “The alteration of motion is ever proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.”
This law is a little more difficult to understand but it is saying that the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, and inversely proportional to the mass of the object. This is Force=mass X acceleration. An example of this law would be if you had two shopping carts and one was entirely full of groceries and the other was empty the empty cart would be easier to push because it has less mass than the full one.
Law 3- “To every action there is always opposed and equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.”
Newton himself gave an example of this when he said “If you press a stone with your finger, the finger is also pressed by the stone.” Meaning that whatever amount of energy and force you exert on an object it will exert the same amount back because for each reaction there is an equal and opposite reaction.
All three of Newton’s laws we discussed and did lecture tutorials on in class. I believe we also watched some simulations of all the forces at work to get a better understanding of what was taking place behind the laws. These exercises along with reading these two articles were altogether very interesting to learn about. They helped a lot to increase my comprehension of this material and have given me a better perception of science and especially Astronomy. These two articles were well written and easy to follow which helped also. One thing that these articles did explain better to me was Newton’s second law. For a while in class I was not understanding the whole “scientific talk” with Force equals mass times acceleration. It sounded like a bunch of math gibberish to me but the articles had some good examples to point out that helped a lot and I am grateful for that. This was yet again another good blog post topic to write on. I hope the next ones will be just as good.