The air you breathe out has a different chemical composition (more CO2, usually more water vapor) and is at a differerent temperature from the air you breathe in. So the buoyancy effects will make a difference.
But trying to measure weight to within 1g, I would be more concerned about random...
And in the spirit of lean manufacturing, you should do that without using any ink :biggrin:
Spend your time at college learning some Mech Eng. Yes I know the ME courses are probably harder than this happy-clappy-mangement stuff, but you usually have to work for the worthwhile things in life.
Measuring anything to better than 0.1% precision is hard, and not a common requirement.
What use you can make of knowing the mass of an adult human, measured to the accuracy of 1cc of water (i.e. 1g) is another question, of course.
That is true, but bear in mind that the best known ones (with natiional companies) have more applicants per place than some degree courses at Oxford and Cambridge.
Companies in the UK are increasingly doing outreach work in schools with kids as young as 14, so they have already identifed the...
Your first hard choice is whether to limit your own life choices trying to patch up your dysfunctional parents' lives, or cut loose from them. Obviously to cut loose you need a job, but it doesn't have to be cleaning and babysitting. Aim for something with regular working hours so you develop a...
A 2-blade rotor has a different moment of inertia about different axes (along the blades and at right angles to them). That can create dynamic instability problems, but it's not likely to affect a low-speed room fan. It is a design issue for 2-blade aircraft propellers and helicopter rotors...
You should be able to find a load cell that will meet that accuracy requirement cheaper that $2500.. For example this has a range of 100kg and accuracy 20g. That was the first one Google found, so you can probably do better.
http://www.robotshop.com/en/type-s-load-cell-100-kg.html...
You won't find 4-bladed fans made in China, because the Chinese think 4 is an unlucky number.
Even in the west, 3 and 5 blades probably "look nicer" (i.e. less boringly symmetrical) than 4 when the fan is switched off.
On the other hand, the fans on the front of most large jet engines have...
The equations of motion for the spring without an extra mass on the end are basically the same derivation as the wave equations for longitudinal waves (not transverse waves in a string under tension).
The mass on the end just changes the boundary conditions at the end.
You will find plenty of...
There isn't an alternative party to the SNP. The Scots have completely given up on the Conservatives, and pretty much given up on Labour. The "western fringes" are the only core Liberal Democrat supporters, just as in England.
Of course Labour committed self-immolaton over that, when Blair set...
Use the identity sin(z)=[e^(iz)-e^(-iz)]/2i.
Or better still, take the general solution as the real part of ##Ce^{st}## where ##s = -b + i\omega## and ##C## is a complex constant.
If you ignore the constraints that you don't like (and make wild assumptions like "I can build perfect, balanced windmills of any size") you can get any answer you want.
In the real world, if you start from the basic assumption that the maximum possible power available is proportional to the...