Question

A balanced lever has two weights on it, the first with mass `7 kg` and the second with mass `25 kg`. If the first weight is `6 m` from the fulcrum, how far is the second weight from the fulcrum?

Answer 1

`1,68m`

Explanation:

We may use the second condition for static equilibrium to solve this problem, that is, that the resultant torque of the system must be zero.
ie, `sum vectau=0`, where `vectau = vecr xx vecF` is the vector cross product of the position vector from the axis of rotation (fulcrum) to the applied force and the applied force.

So in this case,

`r_1F_1-r_2F_2=0`

`therefore (6xx7g)-(r_2xx25g)=0`

`therefore r_2=(6xx7xx9,8)/(25xx9,8)=1,68m`.