Better swimming is a matter of stroke mechanics. This is another way of saying it takes advantage of the laws of physics. The most basic of these are Sir Isaac Newton’s three laws of motion.

Newton’s first law is the Law of Inertia: A body at rest tends to remain at rest, and a body in motion tends to remain in motion unless acted upon by an outside force.

I won’t bother much with the first part of this law except to say that people who are inactive tend to remain inactive until something or someone gets them to move. I hope my columns help to perform that function.

Now, how can a swimmer best take advantage of Newton’s first law? Primarily this involves decreasing resistance, one of two ways to swim more efficiently. (The other is to increase propulsion.) A swimmer’s body will move through the water until outside forces stop it.

One of those forces slowing a swimmer’s momentum is gravity. Gravity works against the vertical momentum of lift from Archimedes’ Principle of Flotation.

By keeping the body as elongated as possible, a swimmer’s weight can be distributed over a greater area. This helps keep the swimmer on the water’s surface.

More important, however, is decreasing horizontal resistance. An elongated body minimizes frontal resistance. I like to use in my clinics an 18-inch two-by-four to demonstrate this. Pushing the board on the flat side, angled either up or down, slows it quickly.

The most efficient way to move it through the water is to turn it on its side. Think about how fish swim. Is it no wonder that I teach swimmers first to push off the wall on their side?

Next, there is a suction force working against forward momentum. Consider how a car or truck’s back end attracts more dirt than the rest of its surface. Thus, a narrow glide can reduce this eddy resistance.

Finally, forward momentum is slowed by friction. Competitive suits are made to reduce skin friction, and swim racers “shave down” their bodies to help. In fact, suits have been banned that reduce the coefficient of friction too much and float the body unnaturally high.

If you want to swim better, more efficiently, be sure to follow the laws.

Dr. Bob Colyer of Bluffton is an actively retired college professor, coach and author of “Swim Better: A Guide to Greater Efficiency for Swimmers & Instructors,” directed primarily to non-competitors.