Answer
given,
length of bar = 80 cm
mass of the bar = 10 kg
smaller mass = 4 kg
distance = 20 cm
[tex]s_1 + s_2 = 10 + 4[/tex]
[tex]s_1 + s_2 = 14\ kg[/tex]
taking moment about B
[tex]s_1 \times 0.8 - 10 \times 0.4 - 4 \times 0.6 = 0[/tex]
[tex]s_1 \times 0.8 = 6.4[/tex]
[tex]s_1 = 8\ N[/tex]
[tex]s_2 = 14 - s_1[/tex]
[tex]s_2 = 14 - 8[/tex]
[tex]s_2 = 6 N[/tex]
difference between two scale = 8 - 6
= 2 N