>> Monday, September 15, 2008
I have a test on Friday and I figured the best way to review is to teach. If I can teach you anything in the next few minutes without totally losing you as a reader, I must know my stuff. Wish us both luck and let's get started.
Introduction to Physics and One Dimensional Motion
First things first. Physics is the understanding of the physical world and an attempt to explain the visible world. Pretty much everything has physics based reasoning behind it. Keep in mind, however, like all true sciences, it is a continuous work in progress. The whole point of science is to test and retest and DISPROVE theories. Yes. It's true. We are trying to DISPROVE things. All the time. Weird, I know.
Physics really has always been studied without meaning to be but leaps and bounds were made when our friend Galileo Galilei (1564-1642) started dropping things off the Leaning Tower of Pisa to show the constant acceleration of gravity.
By the way, constant acceleration of gravity means that everything falls to earth at the exact speed. It's true. The only thing that slows an object down is friction with the atmosphere. If you ball up a feather so you reduce the friction, it will fall at the same speed as a lead pellet the same size. In case you were wondering what this acceleration actually is... it is 9.8 meters per second per second. That means every second, the object falling picks up speed at at rate of almost 10 meters per second more than the previous second. Phew! Just leave me questions if you have any.
Back to Galileo... this really taught us a lot about one dimensional motion (you know, just forwards and backwards in a straight line). Now, to understand one dimensional motion, there are a few "terms to know."
Frame of reference- a starting point. If I look at the problem starting from the ground, but you see the problem starting from the rooftop, our approaches will be very different because our reference frame is different.
Distance- how far you (or an object) travels in a given amount of time.
Displacement- how far from your original starting point you are. This is not the same as distance traveled. If you leave the house in the morning, go to work, and come home, you may travel 40 miles, but your displacement is zero.
Average speed- total distance/total time. It is division so if you traveled a total of 40 miles in 2 hours, you have an average speed of 20 miles(distance) per (/) hour (time). I know I am anti- English system, but I am keeping it in these units to not confuse my American readership! It works the same in SI.
I think that is enough for today. If you wanna get into physics on an easy scale, there are tons of books you can buy that will help you on your quest to becoming an everyday scientist!
The image is a painting of Galileo Galilei facing the Roman inquisition. The artist is Christiano Banti. Image courtesy of Wikimedia Commons.