if a bug is flying around your car while you’re driving 60mph on the highway, is the bug flying at 60mph?
In: 3939
Actual ELI5:
Yes.
But the air in the car is moved by the car, so it’s like a 60 mph wind that carries the bug.
It has nothing to do with speed. It has evening to do with acceleration. You can’t feel speed, you feel acceleration.
Is this supposed to be around “inside” or “outside” your car?
Compared to what?
Compared to the earth? Yes it’s moving at near 60mph.
Compared to the air in the car? No it’s almost stationary.
Speed is always measured in relation to something else.
If you want to get all clever and say “oh I’m relation to everything!” Well I’ve got news for you. The car is doing 60mph on the earth, but the earth is spinning on its axis, it’s also spinning around the sun, and the sun is spinning around the center of the galaxy, and the galaxy is moving, too.
So there is a concept in physics called an “inertial reference frame”, which is basically a way of saying that everything in a certain location is travelling at the same speed in the same direction, it is as if there is no movement at all. This is why you do not feel the rotation of the earth, despite it rotating at thousands of kilometres an hour.
Another way of visualising it is being on a train and throwing a ball. Within the reference frame of the inside of the train, everything is still, so throwing the ball behaves as it would if you were on the ground outside of a train.
OP, right now you are flying at 29 kilometers per second (give or take) around the sun. You’re also going at quite a few hundreds of kilometers per hour as the earth rotates (depends on your latitude).
Yet you feel none of it because, in effect, you only feel what moves RELATIVE to you.
When you’re going a steady 60kph outside – say on a bike – what you feel is not your speed. Its the wind and the road under you that are, relative to you, at 60kph.
Inside a car, the air bubble you carry is steady. The fly therefore feels nothing. If you were going 500kph it would still feel nothing.
Let’s do a thought experiment for a moment.
You’re in a train, traveling 100mph. Outside, you can see the scenery pass. You stand up and walk to the front of the train. Technically speaking, you’d be travelling 100mph plus the speed of you walk. If you walked towards the back, 100mph *minus* the speed of your walk. But you only feel the speed of your walk plus the bumps of the train, but not the *speed* of the train.
So the fly would be much the same. Technically 60mph plus it’s own speed, but it wouldn’t perceive the 60mph as 60.
Now zoom out a little bit, if you want your mind to explode. The earth is spinning at nearly 1,000mph. We don’t feel that on the surface.
Zoom out a little more, and earth is orbiting around the sun at a speed of around 67,000mph.
Zoom out a little more, the sun (and with it, the entire solar system) is travelling through space at around 450,000mph.
But why don’t we feel it?
Perception, and how it relates to you. Others have chimed in on that, but I *still* don’t fully understand it. It blows my mind to think about.
Plus, if you were on a ship travelling the speed of light somehow, you’d technically be going faster than the speed of light by walking towards the front, no? It’s insane to me. Plus, the way time works and speed of light works, you’d travel through freaking ***time*** if you were to go the speed of light somehow.
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