Physics is the study of the physical world. It answers the kind of questions you asked when you were a small child. The questions that many of us no longer ask. Why is the sky blue? Where does the sun go at night? Where does the moon change shape and where does it go in the morning? Why does a pencil appear to bend when placed inside a glass of water? How come you can make a rainbow with a hose on a sunny day? And the question my wife asked her physicist uncle when she was a child; "How are those people able to talk from inside the radio and how come you can hear different people when you turn the knob? And my favorite question, what makes the world go 'round? And sorry people, it's not love.

Physics has answers to all these questions. Einstein said the most incomprehensible thing about the universe is that it is comprehensible. In other words, the most unbelievable thing about all the complexity we see around us is that it can be understood, described, and explained using a relatively small set of laws and theories. Physics is the science that sets out to discover the equations and laws that explain and describe the physical world.

The first topic we will investigate this year are the laws that govern motion. By the 16th century astronomic observations had revealed that we were all travelling through space on a large, somewhat spherical rock, that rotated on a tilted axis and orbited a medium-sized, orange star. That rock, the earth, also curved around the sun in an oval-shaped path. In the 17th century, a physicist was able to explain why the earth had rotated nonstop for over four billion years and why all the planets in our solar system all curved around the sun. 

That physicist was named Isaac Newton, and in the 17th century, he shocked the world by stating that the movement of all the celestial bodies in our solar system was not guided by supernatural forces, as most people of his day thought, but could be explained using the very same physical laws that governed the movement of objects on the earth. For instance, the very same forces that explain why a rock thrown across a field curves to the ground, can also explain the movement of the moon around the earth and Saturn's path around the sun.  Newton's 3 Laws of Motion and his Universal Law of Gravity were the first universal laws proposed by any scientist and went a long way to helping us make sense of all the motion we see around us. How is the earth able to spin day after day for over four billion years without a push? We will answer that question in a couple of months when we study what Newton had to say about net forces and motion.

The first step toward understanding how forces affect motion is to review the unique ways that physicists measure and describe motion. In science, very often, if we want to understand how something works, we start by taking careful measurements. The branch of physics that uses mathematical techniques to describe and measure motion is called kinematics.