Error in Wikipedia Cavendish article

[waverider]

According to Wikipedia, Cavendish was able to measure a force of 1.74E-7 N or “roughly the weight of a large grain of sand[13] of 0.13 mg”

However, with my calculations using m=F/g, where g=9.81m/s/s

Gives m=1.74E-7/9.81 = 1.77E-8 kg = 0.0177 mg

Which is much less than 0.13 mg

Am I missing something?

 

[Drakkith]

Let's see...

0.13 mg = 0.00013 g = 0.00000013 kg = 1.3x10^-7 kg
F = MG
F = 1.3x10^-7 * 9.81
F = 1.28x10^-6 Newtons

Hmm... you appear to be correct.
Perhaps it should be a small grain of sand?

 

[waverider]

Indeed, the Wikipedia weight is 7.3 times higher.
I find it impossible that Cavendish was able to measure such a tiny force of attraction between the metal spheres and this force was able to overcome the air resistance and mechanical friction which was apparent in the apparatus.

 

[pbuk]

What air resistance and mechanical friction?