Understanding the fundamental idea behind rocket science isn’t, well, rocket science. To launch ourselves skyward, we have to throw a bunch of stuff downwards really fast. Most of the time it’s rocket fuel, but all the fire and noise makes that underlying idea hard to see. So what if we used elephants instead?
In the video above, YouTuber Maxim Sachs did the math to show how many elephants it would take to launch a Saturn V rocket like the one that took us to the Moon. However, the numbers in the video description are a bit off, as is his conclusion: there are way more than 1.3 elephants coming out of that rocket every second.
So I did a little math of my own. The combined flow rate for the five F-1 engines powering a Saturn V rocket is around 28,415 pounds (12,890 kg) per second. Elephants range from almost 7,000 lbs (the smaller, female Asian elephant) to over 15,000 lbs (the male African elephant). Let’s call the average elephant 11,000 lbs. Dividing the two values, we get about three elephants per second to launch a Saturn V. The video still looks like it’s putting out more elephants than that per second, but you get the idea.
It sounds silly, but the thought of throwing three elephants out of the back of a metal tube bound for space every second is a great way to visualize what is really going on. Newton’s third law of motion states that every action has an equal and opposite reaction. So if you very quickly throw a lot of mass away from you, you are going to experience a lot of force.
Imagine yourself in the center of a frozen lake: the ice is so slippery that you can’t walk in any direction without falling over. What do you do? You could take some mass, maybe a boot or two, and hurl it towards the shore. You slide back in the opposite direction. Throw enough of your clothes and you’ll soon be at the lake’s bank (and very cold). A rocket does the same thing, but instead of a boot it uses rocket fuel, and instead of a bank its destination is space.
All of this physics talk belies a simple fact: a rocket doesn’t push off against the ground, or anything. If that were the case, if wouldn’t be able to move around the near vacuum of the cosmos. No, a rocket pushes off against itself—whether that’s with thousands and thousands of gallons of exploded rocket fuel or with elephants.
IMAGES: Maxim Sachs