A balanced lever has two weights on it, the first with mass #3 kg # and the second with mass #4 kg#. If the first weight is # 25 m# from the fulcrum, how far is the second weight from the fulcrum?

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Answer 1 · 2016-08-13T15:26:19

#l_2=18.75 " m"#

#"Torque for the first weight:"#

#L_1=m*g*l_1#

#m_1=3" kg";g=9.81 N/(kg);l_1=25 "m"#

#L_1=3*g*25=75*g" " N*m#

#"Torque for the second weight:"#

#L_2=m_2*g*l_2#

#m_2=4" kg" " ; "l_2=?#

#L_2=4*g*l_2#

#L_1=L_2 " so the system is balanced"#

#75*cancel(g)=4*cancel(g)*l_2#

#l_2=75/4#

#l_2=18.75 " m"#