Question

A balanced lever has two weights on it, the first with mass `8 kg` and the second with mass `30 kg`. If the first weight is `7 m` from the fulcrum, how far is the second weight from the fulcrum?

Answer 1

`1.867m`

Explanation:

I will apply the second condition of static equilibrium which states that the resultant torque (moments) must be zero,
ie. `sum tau=0`
where `vectau=vecr xx vecF` is the algebraic cross product of the position vector from the axis of rotation (fulcrum) to the applied force, and the applied force.

So in this particular case,

`r_1F_1-r_2F_2=0`

`therefore(7xx8g)-(r_2xx30g)=0`

`thereforer_2=(7xx8xx9,8)/(30xx9,8)`

`=1.867m`.