The limitations of common sense

I would like to propose a topic here that would investigate the notion of common sense and how much of what we normally take for granted is not so necessarily common sense.The means by which I would like to proceed are by the fleshing out of understanding of the world around us by examining the "common sense" idea that the earth rotates about its axis. {no flat earthers please as there is a 300 post limit}
In doing so I would like to challenge people to try and resolve the questions that naturally arise which tend to be overlooked by people who merely absorb "facts" and not delve into implications of those "facts".
I would also enjoy input from our resident cosmologists and other scientists with the caveat that you stick with statements and questions on the basics of science to allow us an insight into how you think about these questions. As we progress {into different side topics as well as continuation of this one} I would like to see a learning process take place wherein gaps in knowledge and understanding on both sides are realized {or not as the case may be} It would be great if you could present questions to allow us to excercise our brains with actual thinking.First off, we will start with the "fact" taught to us that the earth rotates on its axis in a spin that is completed once every 24 hours.{23 hours 56 minutes 4.09053 seconds for those who care}Depending on where you are located on earth the rotaional velocity is from a little more 1000 miles per hour at the equator {25000 miles divided by 24 hours} to the pole where the velocity diminishes to near zero.
Now we ask the question how do we explain an example of motion meant to test this "fact"?
If we are located at the equator and take take a cannon ,point it straight up and fire a round, does the fact that the earth is rotating at 1000 miles per hour{roughly 1500 feet per second} mean that the round will be many miles away from us when it lands? Why or why not?This would probably be best located in Is it science. moved by the QueenThis message has been edited by sidelined, Sun, 2006-04-09 11:14 AM

PhatCertainly that is the result of experiment. How do we justify the position that the earth rotates around at that speed though if experiment denies what common sense would tell us should happen in that event?

DiscreetLabel

RazdA fine reply I must say However in relation to your statement The cannon does indeed and common sense does not dipute this but the cannon round is what is doing the travelling and this defies common sense. Since the cannon ball is no longer attached to the earth how do we explain that the cannon ball comes down anywhere near the cannon if the earth is now continuing to move 1500 feet per second while the round is travelling free of both cannon and earth?We may also inquire as to how birds flying in the air manage to keep up with the earth as it is travelling at this fantastic velocity.How do birds fly straight north or south while we who are watching them are travelling at 1000 mph eastward?How do we invoke common sense to explain gravity working on objects travelling out of contact with the earth? Perhaps buzsaw could fill this one in.

RAZD But we can say that about the car and the ball because we observe the two travelling together.If a person were to drop the ball from the car then it would end up behind the car as a common sense would dictate since the car is moving. If we stand on an earth that is moving at 1500 feet per second {far faster than the car} it would follow from this logic that a ball released from our hand or a cannonball shot into the air must fall a great distance even in a short period of time.Now what allows us to say that the earth is actually moving and not stationary? The scenarios above apply in both instances. Technically the reason why it does not come down has to do with the shape of the earth since at escape velocity it is still falling towards the earth. It has attained sufficient speed that it falls in sync with the curvature of the earth below, always falling but not losing altitude. Well here is another aspect of observation that is odd. If the earth is moving at 1500 feet per second then why do we not feel the air rushing past us as well? The birds should indeed be blown out to sea.

cavediver This is kinda the point of my opening this thread. We have an opportunity here .As I described in my opening post I would like to do debate on simple assumptions tht we make about the everyday world and the standard "facts" that are presented to us that we do not think deeply about.There are many consequences present in even "simple" laws such as Newtons on motion. We tend to have a superficial understanding of these things and an awful lot of the time some things we are taught are not entirely accurate or the colloquial terms are far removed from the scientific meaning.So I try here to play the devil's advocate by asking what i think the common sense idea would be and see how we respond to the very basic assumptions that we make and see where that leads us.I think it is far more valuable to challenge basic assumptions deeply before tackling some of the issues of cosmology such as the big bang or the nature of spacetime.I do hope that this will be a learning experience for all.

Omnivorous Ok then. Now we need to discuss how the cannonball can be tethered by gravity. In fact, what do we mean by gravity? The common sense evaluation of gravity is that it is an observation that objects sent into the air fall to earth again .We can investigate further as Galileo and others did to arrive at the notion that objects of different masses fall to earth with the same acceleration. How is this possible? How does gravity manage to differentiate the level of mass so precisely that no difference in acceleration is detectable from the force of gravity?

Dominion Seraph Thank you for the correction you are,of course, right. Did you know. though, that the use of the term velocity in escape velocity is not quite correct? Really? Would you care to tell us how that works?
Since the earth is a soid mass it is understandable that it wold move as a unit. However, air and water are both fluid, and thus would seem to not be likely to flow in the same way due to their "viscosity".
Why does the air and ocean travel as though,they too,were solid?

Discreet LabelSorry I took so long replying. Yes, this will do for the purpose of our discussion

cavediverI think this would make a fascinating topic on its own concerning the errors that science has uncovered through investigation. Can you put together a listing in columnists corner that we can use to refer to whenever we have the opportunity? It would be great if we could have examples and possibly some questions thrown in to have us dig through the list to see if we can identify errors properly.I really appreciate your input since this is probably the closest I will ever have to actually going and getting an education through regular schools.That means a lot to me.A question occurs to me also. When you were growing up and questions in physics and math were being presented to you in what way would you go about tackling new concepts?

RAZD But what is it that allows us to differentiate between this as a consequence of a planet rotating on its axis and one that is not? It would seem that the same situation is present in either scenario.
This also ties back into the OP since I was initially trying to validate the position of the assumption that the Earth spins on its axis?
I am also curious as to what other "common sense" discrepencies might occur to someone who does not quite understand the interrelationship of various lines of knowledge?

DominionSeraph This does not explain why the air is already travelling along with the earth. Friction with the crust cannot explain why the atmosphere above the contact with crust also moves along.The issue on the escape velocity is simply that velocity is a vector measurement that includes direction and escape velocity is independent of direction.

petrophysics Of course it can since in the gold panning you are not removing the force of electromagnetism present in the water which provides the resistance to motion. For that same reason, in air, a feather and a lead ball also fall at different rates. The acceleration due to gravity is still the same. It is merely overpowered by the electromagnetic force. That is correct. However,the acceleration due to gravity is still independent of the motion of the earth.

petrophysics In this instance the acceleration by the force of gravity is matched by the force of buoyancy and the net acceleration reduces to zero.The reason is simply that the buoyancy is measured in the same way as the gravityForce of buoyancy is Fb=mg m equal to the mass of water displaced and g equal to gravitational acceleration while force of gravity is also Fg=mg m equal to mass of body and g equal to acceleration of gravity.
Thus,folowing your reasoning, we get Fb/m +{-}Fg/m = g. g = 9.8m/sec^2
so the answer to your question is Yes.In accoradance with Newtons third law the force of buoyancy acts in a equal magnitude but opposite direction to the mass acceleration due to gravity. Since they are equal forces but applied in opposite directions the net force becomes zero.The acceleration due to gravity remains the same otherwise there would be an imbalanced force due to the opposing equal force of the water which would repel the mass and expel it from the water.The force of gravity remains constant thus it is always accelerating at 9.8m/sec^2 on earth.This message has been edited by sidelined, Tue, 2006-04-18 09:36 AM