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Current time:0:00Total duration:4:47

Slow sock on Lubricon VI

Video transcript

this is a piss is a picture of the planet lubricant 6 and lubricant 6 is a very special planet because it's made up of a yet to be discovered element called lubricant and lubricant is special because if anything glides across the surface of lubricant it will experience absolutely no friction so if this right over here is a sheet of lubricant we're looking at it from the side and if we have a brick on top of it maybe gliding on top of it like that it experiences absolutely it experiences absolutely no friction now the other things we know about lubricant 6 is this drifting in deep space and it does not have an atmosphere in fact it is a complete vacuum outside of it's in such deep space such a remote part of space that there aren't even a few hydrogen atoms right over here it is a complete absolute vacuum and it's also an ancient planet the star that it used to orbit around has long since died away so it's just this lonely planet drifting in deep space without an atmosphere the other thing we know about lubricant 6 is that it is a perfect sphere it is a perfect perfect sphere now my question to you for some bizarre reason there happens to be on the surface of lubricon 6 so this right over here is the surface of lubricon 6 there happens to be a sock that is frozen in a block of ice so this is my sock and it's frozen it's frozen in this block of ice and it happens to be traveling at 1 kilometer per hour 1 kilometer per hour in that direction if we were to look at it from this kind of macro scale when we're looking at the planet let's say that that is the frozen sock and it is traveling it is traveling along the equator it is traveling across the equator of lubricon of lubricon 6 so my question to you given all of the assumptions we made that it has absolutely no atmosphere it's a perfect sphere and lubricant Li no friction regardless of what's traveling on top of it what will happen to this rock or I should say to this frozen sock over time to answer that question we need to think about all of the forces that are acting on this frozen block of I guess this frozen block of ice and sock and first of all let's think about the forces that are acting in the radial Direction inward or outward of the center of the planet well this planet has a mass and so you have an inward force towards the planet center of mass and so you have the force of gravity acting on this block going radially inward to the center of the planet so I'll draw it like this so we have our force of gravity we have our force of gravity's going radially inward just like that but then we know that the block is not just spiraling towards the center of the earth we have the surface here it's not going to go through the surface of lubricon also assume that lubricant is a very very very strong material and so you also have a normal force you also have a normal force that is keeping that is keeping the block from spiraling towards the center of the earth so this is a normal force and one thing I'll will think about now and we'll address it directly in another in another tutorial is whether this normal force is equal to the it was equal to the force of gravity we'll think about that in a future video but these are all the forces that are acting in the radial direction either inward or towards the center of the planet or outward but if we think about in the tangential direction along the surface of the planet there are no net forces and because there are no net forces in this tangential direction right over here this block will not either accelerate nor decelerate there is no air friction there is no friction or I should say air resistance which is really just friction with the particles if you had an atmosphere it's a complete vacuum so there's nothing there there is no friction with the surface of the planet so there's no friction there which could have been a which could have been a force in the tangential direction so there's absolutely no forces in the tangential direction so this block of ice will actually continue to travel at one kilometer per hour for all of eternity so it'll just continue to do it given the assumptions that we've just made