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Homework Help
15-09-2006, 03:09 PM
Post: #1
Homework Help

Floops, this may be one for you (no pressure).

It's KS3, Year 7 Science homework.

"Please explain why the sides of a sealed steel can collapse inwards when the air is sucked out of it by a vacuum pump".

Can anyone help?
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15-09-2006, 03:16 PM
Post: #2
Homework Help
yes, I can help Smile

Mick Smile
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15-09-2006, 03:18 PM
Post: #3
Homework Help
Thanks. When you're ready, obviously. I'll just......... wait........ until you're ready........ :whistling:

No rush.
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15-09-2006, 03:21 PM
Post: #4
Homework Help
and the magic word is...?

Mick Smile
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15-09-2006, 03:22 PM
Post: #5
Homework Help
Difference in air pressure Patsy.
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15-09-2006, 03:24 PM
Post: #6
Homework Help
Please, Mik. :wink_kiss

Yes, Grouch, but I need to pad it out a bit and sound like I know what I'm talking about. Or rather, my son does.
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15-09-2006, 03:35 PM
Post: #7
Homework Help
Well, it's what Groucho said.

Basically, the air all round us is under pressure (the weight of those miles of air above). We don't really notice this pressure, because it's all around. If the tin is sitting there with no vacuum in place then there's air pressure on the inside of the can, pushing outwards, and there's equal pressure on the outside, pushing in. So no net effect on the can.

If you seal the tin and reduce the pressure in it, by pumping the air out, then there's more pressure pushingin than out. This difference in pressure makes the walls of the tin push in.

HTH Smile

Mick Smile
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15-09-2006, 03:44 PM
Post: #8
Homework Help
Marvellous. Thanks Mik. Even I understood that.
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15-09-2006, 03:45 PM
Post: #9
Homework Help
How old is your child Patsy ??? That is a blummin hard question.

But what i dont understand is ... they make the questions so hard that the child doesnt know how to find the answer and neither do (the majority) of the parents, so even they end up having for help. How is this aiding the kid ?

In my view questions should be easy enough that with a little thinking, looking up on the internet and perhaps a smidge of help they could do it themselves.

But hey - what do i know.

I'm not perfect, but im so close it scares me
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15-09-2006, 04:04 PM
Post: #10
Homework Help
Patsy Wrote:Marvellous. Thanks Mik. Even I understood that.
My pleasure Pats Smile (hope I got it right, after all that...)

Bons, I don't mind the idea of my kids getting homework I can't help with. What I dread is the kids getting work they know I can help with. Anything for an easy life, me Wink

Mick Smile
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