A balanced lever has two weights on it, the first with mass 8 kg 8kg and the second with mass 3 kg3kg. If the first weight is 2 m2m from the fulcrum, how far is the second weight from the fulcrum?

1 Answer
Jan 11, 2016

5.333m5.333m

Explanation:

We apply the second condition for static equilibrium which states that the resultant torque (moments) must be zero,
ie. sum vectau = 0τ=0,
where vec tau= vecr xx vecFτ=r×F is the cross product of the position vector vecrr from the axis of rotation (fulcrum) to the applied force and the applied force vecFF.

So application in this case yields :

r_1F_1-r_2F_2=0r1F1r2F2=0

therefore (2xx8g)-(r_2xx3g)=0

therefore r_2=(2xx8xx9.8)/(3xx9.8)=5.333m.