May the force(s) be with you

Newton and the laws of frisbee: part 1

One of my physics professors (who was also a frisbee legend) took me out for some object disc golf many years ago. Luckily I didn't get hooked then or I probably wouldn't have graduated from college! Now, I can put some of that physics to practical (?) use:

Isaac Newton would have enjoyed disc golf

Before Niels Bohr, Albert Einstein, and Werner Heisenberg came along with quantum physics and relativity, Isaac Newton was the big dog in physics, and Newton’s laws still dominate the world that most of us live in. Physicists call it classical physics. We call it disc golf physics.

Newton would have loved disc golf, but he was born 300 years too early, so he had to make do with falling apples instead of flying discs.

As the story goes, Newton wondered why the apple always fell straight down toward the ground (and possibly hit him on the head). The falling apple eventually led him to come up with the law of gravitation:

Every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

But what we’re really interested in is

Newton’s law of universal frisbitation:

When applied to frisbees, Newton’s law of gravitation is:

The earth attracts every frisbee with a force that is proportional to the product of the earth’s mass and the frisbee’s mass and inversely proportional to the square of the distance to the center of the earth.

(For practical disc golf purposes, we can ignore the gravitational forces on our disc due to the moon, the sun, other astronomical objects, and other frisbees. The earth is the big player here.) Note also that the direction of forces is along the line between the center of mass of the two objects. For disc golf, that is straight down. There is no gravitational force that pulls to the left or to the right for either apples or frisbees.

Support your local frisbee

When you’re holding a disc, the force you exert upward with your hand balances the force of gravity on the disc and it remains still: the forces are balanced.

If you release the disc, the only force acting on it is gravity, and it will accelerate toward the ground.

Unless you have fun just dropping discs to the ground, there are a couple of other forces involved in disc games, including disc golf. Newton has a few other laws too. We’ll get into them next time…

Thanks for reading, and happy discing!