Today’s post is going to be a little different. I know I usually write about origins of words & phrases, but I’m going to start throwing some science related stuff in here as I write more.
So today I’m going to write a little bit about speed & how what we perceive as fast, really isn’t that fast in the large scheme of things. Hopefully, I can put some of this stuff into perspective for those who don’t know.
Let’s start simply with things we’re used to here on Earth. How fast do you walk? The average running speed of a human is between 5 & 8 miles per hour. Doesn’t seem that fast just yet, right? What if I told you that Usain Bolt holds the record for being the fastest man alive with an average of 23.5 miles per hour? That’s close to how fast you’d drive down a residential side street. Speaking of cars…
We’re going to pick up speed a little, here. Remember how fast it felt when you hopped behind the wheel on the highway for the first time? You were traveling about 65 miles per hour. Keep that feeling in mind while we accelerate to almost 4 times that speed. Depending on the size of the track, NASCAR racecars can reach speeds of up to 230 mph. Those things are a blur as they pass. Now, things are starting to get fast, right? Well, actually no. Let’s keep accelerating.
Airplanes. A normal passenger jet can get you across the Atlantic Ocean in 5-6 hours, depending on what kind of winds it’s facing. That’s because they travel on an average of 600mph. That’s almost the speed at which sound travels through air. That would be 761.2 mph. At this speed, a moving object creates pressure waves which are compressed together because they’re moving too fast to get out of their own way. They mesh into one wave & this creates the familiar sonic boom. 761 miles per hour.
Throttle up. Bullets. Their speeds range, but the average pistol fires a bullet at about 800mph. Certain hunting rifles fire bullets at 2,000 mph & ammunition from some military weapons can reach speeds of 3,000 mph. That’s too fast for the brain to process, so we can’t see it. Believe it or not, compared to other things, it might as well be stopped.
Before I move on, I want to let you know that the reason I kind breezed through those is because, while we consider a lot of those things fast, we’re very familiar with them. Now, it’s time to leave Earth & head into space, where speed & velocity tend to really rocket away.
Speaking of rockets… What do the International Space Staion, the Space Shuttle & the Gemini Capsule have in common? They all orbit Earth. In order to reach an orbit around the earth, the pull of gravity needs to be equal to the velocity of the object. The gravity of the central object is trying to pull the orbiting object towards it, while the orbiting object’s inertia is trying to keep it going in a straight line. It results in a constant free-fall around central body. In the case of Earth, how fast does the orbiting object need to be moving? Well, to us humans, it’s astronomical (Yeah, all pun intended. Har har har). That speed is about 17,500 miles per hour. The website What If, is a weekly updated site which answers questions in layman’s terms about physics. To put that speed into perspective, they put it this way: “The ISS moves so quickly that if you fired a rifle bullet from one end of a football field, the International Space Station could cross the length of the field before the bullet traveled 10 yards.” Nuts.
To be safe for human flight, the space shuttle & other man rated rockets need to accelerate to the same speed, but need to do it in a manner which is safe enough for humans. It reaches it’s top speed in just under 10 minutes. In other words, the when the space shuttle needed to go from 0-17,500 in about 8 minutes. Think about that for a second.
The last bit I’ll give you today is about the Saturn V. That was the moon rocket.
It was bigger, but needed to go much faster than the space shuttle. You see, while something is in orbit, it is still held to the central object by gravity. In order to break this hold, you have to reach what physicists call an escape velocity. The more massive an object, the faster you need to be moving to leave its gravitational influence. The Saturn V was a three stage rocket. That means it had three parts. All three stages of the rocket fired to put it into a temporary orbit around Earth. When everything was squared away & stowed properly, the third burned again to accelerate the spacecraft to reach Earth’s escape velocity of 25,000 miles per hour. That’s about 7 miles per second. The spacecraft would’ve covered 28 miles in the time it takes you to read this sentence, which means the astronauts who flew in the Saturn V hold the record for being the fastest humans on (& off) Earth.
That’s it. Humans haven’t moved faster than that yet. Hopefully, we’ll reach faster speeds as we head to other planets in the future. At any rate, I figure reaching the end of man’s physical capabilities is a good place to put the bookmark, but believe it or not, what I’ve discussed so far doesn’t even begin to scratch the surface of the mind blowing speeds the rest of Universe is capable of. I’ll touch upon those next week
For now, this has been another installment of Bill’s Bologna. Thanks for reading. You can walk away knowing just a little bit more about than you did 10 minutes ago.
Now you know. You’re welcome.