I came across an interesting question which brought me back to highschool physics. Want to hear it? Probably why you're here...
If I'm travelling forward in a car at the speed of a bullet, and my partner in crime shoots an actual bullet out of the back of the car (ignoring the windshield), what happens to the bullet?
Hm, seems simple right? It is if you have a basic understanding of vectors!
Remember vectors? Imagine an arrow, pointing in the direction of the car, and another pointing in the direction the bullet was fired. So you should be picturing two arrows pointing in the opposite direction of each other.
Now vectors aren't just arrows, they represent both direction AND magnitude. Magnitude in this case being the speed of the bullet, which was also the speed of the car. So these arrows (vectors) are equal in length (representing the magnitude) and opposite in direction. Pretty easy to follow, right?
Now, here is where I want you to think of the scenario mentioned at the beginning, what will actually happen to the bullet?
Well, think back to the vectors. If we overlay the vectors, one on top of the other, what would the net vector be? In other words, would any vector piece remain when overlaying the two arrows?
No! They were equal in size! And since they are opposite in direction they cancel themselves out. So, simply, the bullet would fall, straight down, due to gravity.
Does this surprise you? It would definitely seem weird since it would be as if the bullet is shot from the gun and then just falls, losing all of its momentum, or having none at all. But picture yourself as the bullet.
If I was the bullet and was shot from the gun, remember, the gun is travelling forward (in the car) at the same speed as the bullet would be travelling if fired in a still car. It would seem as if everything was normal. I, the bullet, was shot from the gun and travelled at the speed a bullet normally would travel. So relative to the gun, more so, relative to who shot the gun, the bullet would appear to go in the direction fired and at the speed expected. But relative to me (the bullet), the car is travelling away from me just as fast as I should have gone, so it would seem like I stood still and the car flew backwards.
It takes a little to wrap your head around, but that's relativity!
So how else does relativity make things appear as normal but in reality are kinda weird? Well, our planet has a north and south pole. In other words, there's a top and a bottom. So how come the people on the bottom, say, in Antarctica, aren't upside down all the time? If you look at the Earth from space, it's a sphere, a ball. If you held a ball out in front of you and pictured tiny people with their tiny feet standing around the entire surface, only a few of them would be standing up straight, to your eyes. But in real life, to those people, they aren't upside down or sideways, they stand just like you do.
That's the beauty of relativity.
Thanks for reading!
If I'm travelling forward in a car at the speed of a bullet, and my partner in crime shoots an actual bullet out of the back of the car (ignoring the windshield), what happens to the bullet?
Hm, seems simple right? It is if you have a basic understanding of vectors!
Remember vectors? Imagine an arrow, pointing in the direction of the car, and another pointing in the direction the bullet was fired. So you should be picturing two arrows pointing in the opposite direction of each other.
Now vectors aren't just arrows, they represent both direction AND magnitude. Magnitude in this case being the speed of the bullet, which was also the speed of the car. So these arrows (vectors) are equal in length (representing the magnitude) and opposite in direction. Pretty easy to follow, right?
Now, here is where I want you to think of the scenario mentioned at the beginning, what will actually happen to the bullet?
Well, think back to the vectors. If we overlay the vectors, one on top of the other, what would the net vector be? In other words, would any vector piece remain when overlaying the two arrows?
No! They were equal in size! And since they are opposite in direction they cancel themselves out. So, simply, the bullet would fall, straight down, due to gravity.
Does this surprise you? It would definitely seem weird since it would be as if the bullet is shot from the gun and then just falls, losing all of its momentum, or having none at all. But picture yourself as the bullet.
If I was the bullet and was shot from the gun, remember, the gun is travelling forward (in the car) at the same speed as the bullet would be travelling if fired in a still car. It would seem as if everything was normal. I, the bullet, was shot from the gun and travelled at the speed a bullet normally would travel. So relative to the gun, more so, relative to who shot the gun, the bullet would appear to go in the direction fired and at the speed expected. But relative to me (the bullet), the car is travelling away from me just as fast as I should have gone, so it would seem like I stood still and the car flew backwards.
It takes a little to wrap your head around, but that's relativity!
So how else does relativity make things appear as normal but in reality are kinda weird? Well, our planet has a north and south pole. In other words, there's a top and a bottom. So how come the people on the bottom, say, in Antarctica, aren't upside down all the time? If you look at the Earth from space, it's a sphere, a ball. If you held a ball out in front of you and pictured tiny people with their tiny feet standing around the entire surface, only a few of them would be standing up straight, to your eyes. But in real life, to those people, they aren't upside down or sideways, they stand just like you do.
That's the beauty of relativity.
Thanks for reading!
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