Beleive it or not there is a huge range - smallest around 700kg, largest well over 5 tonnes - large Bentleys. RR's etc. Educated guess at an average - around a tonne, probably a little more.
Do you mean landmass or people?
not much really
In the UK the huge majority are 250g.
Auto Trader - UK - was created in 1975.
1 Gallon of gasoline weighs 6.152 lbs.
My 1970 SS weighs 3600 lbs. SBC, Auto, no air.
short bed 4x4 318 auto trans 4800lbs
She's a healthy size 12(UK)!
A UK £2 coin weighs 12 grams so 80 of them will weigh 960 grams.
A 50p coin in the UK weighs 8 grams.
A 2 pence coin in the UK weighs about 7.12 grams.
Around the £10..00 per hour mark here in the UK.