Counterweights on a tractor

 

These iron blocks are 5cm wide and 50cm long. I'm estimating about 25cm deep. That means a volume of 6250 cubic centimetres. The density of iron is 7.9 grams per cubic centimetre. The mass of one block is therefore 49375 grams to too many sig figs. Since I'm extimating, best to say 50kg. There are 8 of them. That means 400kg. Not quite half a tonne!