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

1 Answer
Trevor Ryan.
Mar 24, 2016

#4.5m#

Explanation:

From the second condition for static equilibrium, the resultant torque (moments) must be zero, ie #sumvectau=0#, where #vectau=vecrxxvecF#.

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

#therefore (9xx4g)-(r_2xx8g)=0#

#thereforer_2=36/8=4.5m#.

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