Once upon a time, Sir Isaac Newton had a cannon. Noisy thing that. Orbitologists call the figurative device “Newton’s cannon.”
I managed to borrow one of these cannons from the National Museum of Orbitology and Conjecturism, and am standing next to a large pile of cannonballs (see image).
Depending on all sorts of factors, like how much gunpowder, how big the cannonball, etcetera, I’ve discovered the cannonball leaves the cannon around 1440 feet per second. Alas, after leaving the cannon, the speeding cannonball gets affected by wind, gravity and distance it has to travel.
The first factor is the wind resistance. At 1440 feet per second on a calm day, the spherical ball of lead immediately encounters 1440 feet per second wind resistance in the opposite direction of flight. The cannonball’s gonna slow down.
The second factor is gravity. No matter how fast that thing travels through the air, it’s still going to fall toward the ground for the same reason we plant our feet here. Gravity.
A third factor, I suppose, is if we’re shooting at a target or just an open space to see how far the ball will travel. Since I want to see how far the ball will go, I’m in an open field.
A fourth factor is trajectory. Am I shooting level to the ground, or in a big arc? Obviously it’s going to travel farther if I angle the barrel of the cannon up and shoot the ball in a big arc. So what to do? Let’s just put a level on the barrel and shoot it parallel to the ground to see how far the projectile is going to travel before wind resistance and gravity pull that hurdling ball of metal down to the unyielding ground below and then it bounces and rolls until it comes to a halt.
Now that we’ve fired the cannonball, let’s take a tape measure and see how far it went before it hit the ground. Surprising distance it seems for such a big heavy object. I wonder if we could make it go any farther?
This is the example of Newton’s Cannon. Given a condition of no atmosphere, and enough speed, that ball would travel around the curve of the earth, hitting further and further away from us. Speed it up even more and it will never hit the ground (see illustration).
That’s an orbit.
Umm….wait. Something’s seriously wrong here. My brain puts up red flags. I’m a layman, not a real scientist, so what do I really know about physics and all that stuff. I’m a buff isn’t it enough? Seems to me that a falling object should accelerate, not just fall at a constant speed. Seems to me the rate of acceleration of a falling object is (Googling it now) 9.8 m/s/s.
“Free-falling objects are in a state of acceleration. Specifically, they are accelerating at a rate of 9.8 m/s/s. This is to say that the velocity of a free-falling object is changing by 9.8 m/s every second.” –physicsclassroom.com
So the cannonball should not just curve around with the curve of the earth, but accelerate downward as it falls, thus never achieving orbit and always hitting the ground. Therefore nothing can orbit anything and the moon can’t stay in the sky and the Earth is going to fall into the sun. The International Space Station is doomed tomorrow and all the GPS satellites are going to fall down. Forget about Dish Network, DirectTV, SeriusXM Radio, weather satellites and Google Earth. It’s all coming down.
Right?
Well, obviously wrong, but why wrong? This is a question this layman has pondered over many an hour sitting in pondering places at various pondering moments in this pondering life. I suppose I’m going to have to just ponder up another Google search. I will ask this question another way posted here, and after you read that one you can read here and then here!