[Physics Class Notes] on Why Doesn't The Moon Fall Into The Earth? Pdf for Exam

We have been observing the moon since we were little and while many things have changed, the moon has remained constant. While it might appear to change its shape occasionally, it has never changed its position. The moon might not appear for a couple of nights but then it always makes an appearance again, coming back in its full glory. So there might be a question, that many of you would have in the back of your minds, why does the never fall on earth? What is it that keeps the moon away from earth? Well let us try and explain this phenomenon.

Gravity is a very fascinating topic in physics. As children we might have thought it is some kind of magic. But the reality is, it is just science. Let us have a brief into the reasons behind why the moon is not falling onto earth and how it continues to maintain perfect distance and equilibrium with earth. There is a strong gravitational force between the earth and the moon. So then, why isn’t it attracted to the planet earth? This is because the gravitational force isn’t intense enough to pull it to earth.

Gravity

As a child, even we used to think it was some magic, but we hate to break it to you, that’s not magic, it’s science. This is relatively close to magic, and today, we are going to talk about how the moon is not attracted to Earth and how we are safe from getting hit by the moon anytime soon.

Instead of asking why the moon doesn’t fall on Earth, you need to ask Why the moon is not attracted to Earth? This is a better way to put words to this question. The gravitational force between Earth and the moon is strong. But the force is not strong enough to pull the moon towards us, like an apple falling from the tree due to Gravity. 

 

What Keeps the Moon in Orbit Around the Earth?

From Earth, it might look like the moon is stationary, meaning it is not moving, but in reality, each year the moon gets 3 cm away from Earth. Without having the force of Gravity from earth-moon would have just floated away from us. The moon’s velocity and distance from Earth allow it to make a perfect balance between fall and escape.

In case the velocity of rotation of the moon was a little bit faster, it would have escaped the Earth’s Gravity. On the other hand, if it’s a little bit slower, it would have fallen on Earth. That’s why the moon doesn’t fall on Earth.

 

What Happens if Earth Doesn’t Have Gravity? 

We have told you about how Gravity depends on the distance too. You might have seen Astronauts in the space they are floating inside the space station and when they are doing the spacewalk. That’s a clear example of humans able to escape the Gravity of Earth. It does take a lot of energy to leave the Earth’s atmosphere and then go to space. But once you are in space, no force is holding you back from flying like a Superman.

On the other hand, there is a downside of not having any Gravity. If on Earth we don’t have Gravity, the Earth won’t be present in the first place. The big chunks of it will break and float away in space. In addition to this, if somehow Earth managed to keep itself together still, there will be no water and atmosphere on the surface of the Earth, and thus, no living organism will be able to survive such a harsh environment.

 

 

Furthermore, if we were somehow able to live on Earth, our bodies will have no shape, meaning the body structure that you see right now in all animals will not be present. Yes, you will be like Jelly, and your bones and organs will move inside your skin from place to place. We are sure nobody wants to have that kind of experience.

To keep their muscles intact, astronauts in space take more than 3 hours of daily exercise routine. Even after all this exercise, astronauts still need rehabilitation to get back on their feet to move around freely. One more thing we would like to tell you, with massive Gravity comes time travel. Yes, we are not joking here. A Russian cosmonaut named Sergei Krikalev spent 803 days on a space station revolving around the Earth. The gravity pull on the space station was less compared to the pull that we have on Earth. As a result, Krikalev lived 0.02 seconds less than everyone on Earth. 

This is the only way we can time travel right now. If an object is big and has a massive gravitational pull, then time around that object will slow down. This was also depicted in Interstellar, a Sci-fi movie by Cristopher Nolan, who showcased how time affects a person when they get close to Blackhole.

 

What is the reason behind the moon remaining in the orbit surrounding the earth?

From the position of the earth, it might appear that the moon is stationary, however the fact is the moon keeps getting 3 cm away from the earth every year. Without the force of gravity, the moon would have just vanished away from us. The moon’s distance from earth and its velocity enables the striking of the perfect balance between crashing to earth and escaping away. If the velocity of the moon’s rotation was a bit faster, then it would have managed to escape the gravity of earth. And if the velocity was a bit slower, then the moon would have crashed on earth. The fact is it is neither and the velocity is just right for it to stay where it is. 

The gravity of earth is an important factor in keeping the various planetary bodies and objects the way they are. So for instance if earth didn’t exhibit any gravity, then it wouldn’t exist in the first place. Without gravity massive chunks of earth’s surface will break and just float away down the space. Even beyond that, without gravity there will be no atmosphere or water on the earth’s surface and as a consequence no living being would be able to survive this harsh environment.