A balanced lever has two weights on it, the first with mass #3 kg # and the second with mass #1 kg#. If the first weight is # 7 m# from the fulcrum, how far is the second weight from the fulcrum?

1 Answer
Jan 3, 2016

Answer:

#21m#

Explanation:

We apply the second condition for static equilibrium which states that the result torque (moments) must be zero,
ie. #sum vectau=0#, where #vectau=vecrxxvecF# is the 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 (7xx3g)-(r_2xx1g)=0#

#thereforer_2=(7xx3xx9.8)/(1xx9.8)=21m#.