:-)
Hence my Q to the TNP about spring scales vs. a proper balance. The former measures weight by having gravity stretch a spring (so your 1kg mass weighs 1kg on Earth and 1/6kg on the moon), whereas a proper balance compares masses by having gravity pull on them both (unknown mass in one pan, known masses in the other).
120Kg is always a mass. It's not like pounds, where you have pounds mass and pounds force, and the weight of a pound mass is a pound force under Earth Normal gravity.
Andy
Who are you trying to kid?
The OP never mentioned mass or weight, he simply said "Can anyone tell me how much energy is expended lifting 120kg through 5 metres vertically please". That is pretty unambiguous!
nope 120kg is also a weight.
Not if you are a pedant and want accurate answers.
To be really picky the Earths gravity is variable and is differnt at differtn places although not by nuch. They're mapping the moons gravity soon, apparently using two 300Kg satterlites which will orbit 55 Km above rthe surface. The satterlites will be aboit 100-200km apart and the differncde in gravity will cause teh distance between them to change by about the width of a human blood cell. I find it amasing they can meaure such distancies to that accuracy
You are TNP, ICMFP (well you spell like him after he's had a few drinks or maybe its the odd ministroke).
If you want to be really picky the OP asked how much energy was used lifting the mass by 5m not how much energy it gained. That of course depends on the efficiency of whatever is doing the lifting which all the posts have ignored.
Also the posts have ignored the fact that the path followed is not a straight line if you raise it to a point vertically above its original position over any period of time as the earth rotates (and moves through space). Also buoyancy of the atmosphere, tidal effects of the sun, moon, etc., and other physics that affect the answer.
All of which we can ignore as only physicists even know they exist. ;-)
I didn't mention the gaining of energy.
And where in the world as that too makes a difference, but only slight. And of course the hieght.
You'd have to make sure the person was lifting vertically too and not leaning to one side. You'd also have to consider height.
Yep, and moslty insignificant, I doubt such things will be taken into account during the olympics, but it is interesting to have some sense of scale of these things.
We can probably ignore them, but I do like to know about such things even if I'm not a physicist
Not in any lab I've ever been in.
Andy
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