okay so 1/2 acre and you want to know how many times the wheels rolled and the wheel is 16" in diameter?
hold on just a second.
I will assume that mower has a 18" cutting width for my calculations....
1/2 acre = 18000 square feet
18000 square feet = 1200" x 2160" yard (to make it easier)
assuming your dad's mower cuts an 18" path he would have to make 66.7 passes to cover the 1200" side of the yard (width)
We'll call it 70 passes because we all know you have to overlap the blades each pass.
so 70 passes across 2160" (length), wheels turn 1 rotation every 16" according to you
So on one pass of 2160" the wheel turns 135 full rotations.
135 x 70 = 9450 rotations of the wheel per 1/2 acre mowed. approximate
Dont forget that sucker has 4 wheels and you might want to add a bit in for turning and ligning up each pass......hahaha
If you powdercoat the yard you may not ever have to mow!
Does the old mower run again?