An object of mass 0.2kg and density 600Kgm-3 is suspended with a string so that 1/10 of it is immersed in paraffin of density 900Kgm-3. Find the tension in the string

Answer 1

what is its volume?
mass = density * volume
so
0.2 kg = 600 kg/m^3 * V
V= [ 0.2 / 600 ] m^3
vol of paraffin displaced = [ 0.02 / 600 ] m^3
so force up from paraffin = 900 kg/m^3 * [ 0.02 / 600 ] m^3 * 9.81 m/s^^2
= 0.294 Newtons
tension = 0.2 * 9.81 - 0.294 = 1.96 - 0.294 = 1.67 Newtons