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

1 Answer
Jan 11, 2016

Answer:

#5.333m#

Explanation:

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

So application in this case yields :

#r_1F_1-r_2F_2=0#

#therefore (2xx8g)-(r_2xx3g)=0#

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