Determine the dynamometer readings if a 50 cm3 steel bar suspended on it is lowered into kerosene.

Dynamometer readings until the block is placed in kerosene will be equal to gravity
F = mg, here m is the mass of the bar, we find it m = V * ρ, where V is the volume of the bar 50 cm ^ 3, ρ is the density of the steel, we find from the table.
F = V * ρ * g = 0.000050 m ^ 3 * 7800 kg / m ^ 3 * 9.8 m / s ^ 2 = 3.822 N.
When the bar is lowered into kerosene, the buoyancy force of Archimedes Fа = g * ρ * V will act on it, here ρ is the density of kerosene in which the body is placed.
Fa = 9.8 m / s ^ 2 * 800 kg / m ^ 3 * 0.000050 m ^ 3 = 0.392 N.
Dynamometer reading = 3.822-0.392 = 3.43 N.