phys (1023) - Space: gravity & orbit

today we talked about the earth's gravity, and i did the best i could paying attention to all that formula crap.

mr pitt started by asking us the unit for gravity.

some people said ms^2, others said it was N/kg. and apparently the N/kg was the correct one.

it goes like this:

w = mg

where w = weight (a force, so F)
and m = mass (in kg)
and g = gravity

switch that all around and you get..

g = F/m (aka N/kg.. get it?)

anyway.. we also talked about a few other.. random things. like building 6400km high ladders and jumping off. yeaahh.. apparently you'd need to be at a speed of something like.. 27000km/h? in order to stay in orbit and not come back to earth.. coz even firing a bullet would fall down again.

also, at the equator.. one would move at 1700km/h. now in order to have a satellite that would be geosynchronized? id unno if i heart pitt correctly.. but yeah.. it'd have to be 36000km up. or did i mix up my stats.. crap.. must double check and edit this post if i mixed it up.

but yeah.. satelllites like to be at that level so dishes can send signals to the same, "stationary" satellites. basically.. the satellites are in sync with the earth's rotation so it moves at the same rate, as if it doesnt move at all.. geographically