Recent content by Zetan

Thank you, that's given me a nice clear picture.

Yet another question: If all matter is moving through space, is there such a thing as a truly stationary 'object', how would we know it was with nothing stationary to measure it against? In other words - If an object in space is described as being in a complete state of rest, what is that...

One last question to clarify if I have understood this or not!: If there were 2 rocks in space, exactly the same mass, one of them is traveling at 30mph and then collides with the stationary rock, would both rocks end up traveling at 15mph because of the equal opposite force from the stationary...

Because this is all new to me and dare I say it, I had no idea what F=ma described. I should have looked that up first or asked. However, I didn't want to test everyones patients to much! I have just looked up the definition of inertia and F=ma which has made it slightly clearer!

It definitely helps build a clearer overall picture

Yes, that's what happens when one looks on Yahoo for information :smile: Probably best avoided. Although some of it helped. Just to check - is it right to say that it is the 'Inertia' of a moving barge that makes it 'hard' to stop? In other words, a 'stationary' object has no inertia?

Interesting, thanks. I had to change the image in my mind of objects "dropping", to one of objects being pulled, from a standstill by the same force? Came across this on Yahoo to: "The keyword is INERTIA. It's a tendency of an object to conserve its momentum: a stationary object will try to...

Another question I have is (this might need a new thread?): If you have two balls exactly the same size, one made of lightweight foam and the other of steel, why do they fall at the same speed in a vacuum? When you hold them in each hand, why does it take less effort to hold one up than the...

It's probably my fault for not explaining exactly why I wondered whether a vacuum would have a similar lifting effect to warm air, as I didn't know about buoyancy and why less air mass would lift the weight of the entire balloon and basket, etc. It has ended up even more interesting though...

Ah yes, thanks. That must mean that when the balloon is inflated to the point where neutral buoyancy is achieved, the balloon material must be able to expand further for the volume to increase to achieve lift off then? You'll be glad to hear that I am not a hot air balloon pilot! :eek:

Is that why oil stays separate from water, the oil molecules not being attracted to the water molecules? What creates the mutual attraction? Is the force similar to magnetism or something completely different? I suppose if it were similar to magnetism there would be degrees of attraction and...

That's what I wanted to know, thanks. It was thinking about why warm air rises that started me off. I suppose as the air inside of a hot air balloon warms up and expands it is expelled through the hole at the base until there is less weight of air inside?

Thanks, it looks like I need to read up on surface tension to, just to see what causes it! There are so many branches to go off on :smile:

Just to make sure I've got this - does an object placed on a set of scales in a vacuum weigh more than it does in "normal" air pressure, because air is fluid and is pushing on the object from all directions including upwards?

As with an air bubble in water then...