OK
Suppose we have
- body of weight W N
- Maximum pressure endured Pmax Nmm^-2
- Area of each pin is a mm^2
- And X pins
The weight must be distributed evenly the
X pins and given the surface area of each pin this will be an area
X.
a
The maximum pain threshold
Pmax is defined as force / area
This gives us:
Pmax = w / (X.a)
Rearranging gives
X = W / (Pmax.a)
An examination of the units show they cancel out
Plugging in the numbers gives 162.5
Since we canot have 0.5 of a pin, we round up to give the answer of 163 pins
Pluging the nuimbers back
Pmax = 650 / (163 * 1) = 3.99
Just under tollerance
QED