Okay so the question is:A crane lifts a 35,000-N steel girder a distance of 25 m in 45 sHow much power did the crane require to lift the girder? Write your answer in kilowatts.I did the math like this : 35,000 / 45 777.777778 (I put 778)Problem is it says to put it in kilowattsIsn't that, like, 1 kilowatt 1000 watts?If so, how does that make sense?Thank you, any help is appreciated.
You are confusing aluminum with aluminum oxideThe first is a metallic element and the second is a compound of aluminum and oxygenAluminum doesn't rust, as that term is reserved for ferrous metals, ie containing ironAluminum will oxidize but not rust.
Aluminium has a high charge density 3+ It is also very small with a high charge to size ratioNow if you stick something very electronegative such as oxygen next to a highly charged cation the bonds are going to be very strongMore energy is needed to break the bondsWhich is why it is quite unreactiveCovalent bonds form.
Anti rust paints are made out of oxidesThe oxide layer you mention is the protection for aluminum against further corrossionyou can see rusting aluminum to the limit if you induce it, for example, I once saw an old airplane whose wings and rivets created spots of heavy corrossion, due to the fact that both aluminum ribets and aluminum metal in wings had different formulas, of blends, which created a galvanic par that created holes where once were clean, neat ribetts, and the the plane became unusable, kaput!
Rust as we know it is a common term for ferric oxide, which is corrosion/oxidization of iron alloysSo technically, aluminum does not rustHowever, aluminum does oxidize very rapidly when exposed to airSo aluminum always has a thin coating of aluminum rust (perhaps alumrust would be the term?)The good news is that aluminum oxides are very thin and remain well bonded to the surface forming a protective coating that helps protect from further, deeper corrosionFerric oxide on the other hand flakes easily from the surface and forms cracks that actually assist the corrision processCaution though that under the right conditions, heavy corrosion of aluminum can occur resulting is similar flaking of the oxides and loss of the protective oxide layerI've seen dusty piles of aluminum oxides when aluminum was used in a highly corrosive environmentAlso, consider that there are steels that are highly resistant to corrosionThink surgical stainless steelAll metals can and will form oxides.
you just use your formulas W F x P W / t W 35,000 25 875,000 P 875,000 / 45 19 10^3 watt converted to kilowatts this becomes 19 Kw
