Also as for mass of ruler, we could do a preliminary estimation
Ruler would be 100cm long, perhaps 4cm wide and prolly 0.5cm thick
This would give vol. of 200cm3
Density of wood tends to be ~0.5 (depending on type, anything between 0.3 to 1.2, but the ones more than 0.7 are less common)
So the mass = dxv=0.5*200=100g, sounds about right P:
I wrote 250g cause I'm stupid like that.
I wrote 50g...lol I should have written 100g....but I think 50 would be accepted...