A balanced lever has two weights on it, one with mass 4 kg4kg and one with mass 8 kg8kg. If the first weight is 9 m9m from the fulcrum, how far is the second weight from the fulcrum?

1 Answer
Mar 24, 2016

4.5m4.5m

Explanation:

From the second condition for static equilibrium, the resultant torque (moments) must be zero, ie sumvectau=0τ=0, where vectau=vecrxxvecFτ=r×F.

therefore r_1F_1-r_2F_2=0, where F=W=mg.

therefore (9xx4g)-(r_2xx8g)=0

thereforer_2=36/8=4.5m.