Share Tweet Email. Share: Share Tweet Email. Another day, another hoax sweeping the internet. This time, people are trying to fool you into believing that something unique about the Earth's gravity is allowing brooms to stand up on their own.
Gravity isn't a spell from the wizarding world of Harry Potter. The fact of the matter is, the other planets in our solar system are much too far away to have any effect on broomsticks or tides or anything else here on Earth. But this raises an interesting question: Could the broom challenge work the way people on social media think it does if there were another planet much closer to us? Maybe even a ginormous asteroid? What kind of force would this require?
No brush at the bottom, no advantageous low center of gravity. Don't worry, we make these kind of weird brooms in physics lab. The broom has to stay on the ground, so the net force on the bottom mass has to be downward.
But to stay upright, there must also be a net upward force on the top mass. If I draw the forces on these two masses, it might look like this:. I tilted the broom to the side a little bit so you could see that this upward force on the top mass would straighten it up.
Now for the tough part. How close to Earth would a planetlike thing have to be such that the net forces on these two masses pull in different directions? Suppose there is a giant space rock with mass M p at a distance h above the ground. The gravitational force from Earth is constant, but if the other planet is close enough, it can pull more on the top mass than the bottom one. Maybe this picture and these equations will make things clear:. It's not obvious how to make this work, so let's just pick a value for the size of the planet.
I'll assume it has a mass of 10 20 kg. Yes, that's small for a planet—about a thousandth the mass of the moon—but I want to get it close to Earth. The bristles are soft enough to spread out a bit at the contact point with the floor and provide a stable base to support the handle and allow the broom to balance.
Of course, believing that it is the alignment of planets, otherworldly beings, or the moons gravitational pull is way more fun to talk about than the real explanation. Here are some other fun simple physics demos you can do. This site uses Akismet to reduce spam. Learn how your comment data is processed. Click to Share! We couldn't find anything from NASA to support the tweet. But as with many things on the internet, people ran with it. Harris dyantaatnaydh February 10, Fun, right? But the truth is, you can make a broom stand upright today
0コメント