A balanced lever has two weights on it, the first with mass 7 kg 7kg and the second with mass 25 kg25kg. If the first weight is 6 m6m from the fulcrum, how far is the second weight from the fulcrum?

1 Answer
Dec 24, 2015

1,68m1,68m

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=0τ=0, where vectau = vecr xx vecFτ=r×F 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=0r1F1r2F2=0

therefore (6xx7g)-(r_2xx25g)=0

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