Science heads needed

Figment

Ive designed myself into a corner and now i need to get my facts straight

I need to know an altitude of a 30th floor of a building.
Then i need to know the force of gravity at this altitude and what a 1kg bag of sugar would weigh at this altidude.

Also how is wind speed measured?

Last time i try and be clever!

seamus

Unless you want to be ultra-accurate, the force of gravity at 240 feet (roughly 30 floors?) is the same as that at 0 feet - 9.81 ms^-2. Any difference in the force is negligible.

So a 1kg bag of sugar still weighs 1kg.

And wind speed is either measured in knots of kph, I'm not sure.

Offy

Weight does not change with height, pressure however does. The higher you go the lower the boiling point goes, water for example will boil at 100°C at sea level but will boil at a lower temperature on top of K2, 68°C or 78°C I think, don't quote me on the exact temp.

Figment

Weight does change, its mass that doesnt change.
Though i believe in the american system weight means weight or mass.

seamus

Weight does change yep, but only when you're far enough from the earth. There is a negligible decrease in mass for relatively tiny increases in height, such as a tall building.

The weight of the sugar may not be 1kg exactly, probably more like
0.99999999999999999999999999999999999999999999kg, so for all intents and purposes, is 1kg

SkepticOne

Originally posted by Figment
Weight does change, its mass that doesnt change.
Though i believe in the american system weight means weight or mass.

Yeah, kg is a unit of mass in the metric system. The unit of weight would be newtons since it is a force. I suspect this is a trick question since nothing 'weighs' 1 kg, strictly speaking.

I would go for approx 9.81 newtons as the answer.

Force = mass * acceleration = 9.81 newtons.

where

mass = 1 kg and accelleration = g = 9.81 m/sec^2.

In the imperial system the concepts of mass and weight are mixed up so 'pound' is used for both mass and weight.

Figment

Thank you all for replying and for the education
All be adjusting the design slightly to make the science easier.

daveirl

This post has been deleted.

Figment

OK, i have changed around what details im going to show in the design.
Ill post the design when im finished.

I found this site:
http://aerospace.colorado.edu/classes/2002/aero/atmosphere.html

Which has an atmosphere model. Does it look correct to people?
Im using the 30th floor of a building standing in the heart of dublin. The floor is at a height of 400ft (height of spike). And placing dublin at a height of 72 ft above sea level.
So using an altitude of 472 ft i get these details back:

Geometric Altitude 472 ft

Geopotential Altitude 471.98931 ft
Temperature 517.004 deg R
Density 0.0023443 sl/ft^3
Pressure 2080.41 lb/ft^2
Speed of Sound 1114.481 ft/sec
Viscosity 0.00016109 lb sec/ft^2

Does it look right to you? its for a desktop image that is to be on the desktops of teachers and scientists.
Thanks,
Al

amen

why are you using the imperial system Viscosity 0.00016109 lb sec/ft^2 ?
you would be much better off using metric
and what is a Temperature 517.004 deg R ? Whats deg R ?

e

SkepticOne

Originally posted by amen
you would be much better off using metric
and what is a Temperature 517.004 deg R ? Whats deg R ?

I think it is meant to be kelvins. That's what is on the website.

daveirl

This post has been deleted.

Ciaran

Originally posted by amen
Whats deg R ?

I think Degrees R are the farenheit equivalent of Kelvins i.e. an increment of 1R is the same as of 1ºF and 0R is absolute zero.

daveirl

This post has been deleted.

Woden

eh i think R stands for Rankine another unit of temperature don't know how it relates will look into it

Woden

ok what i've figured is that one Rankine=0.556Kelvin and that the scale is linear i.e 10R=5.556K etc. Don't know where it came from did some thermodynamics this year and don't think it was ever mentioned it probably only has a niche use or something as for those other units get with the m.k.s man thats shocking.