JAMB Physics 2012 Paper

Concept:Apparent weight is the actual weight of the object minus the upthrust (buoyant force) acting on it when it is immersed in the liquid.Explanation:Actual weight of the object = $\text{mass} \times g = 2 \times 10 = 20 \, \text{N}$.Mass of liquid displaced = density of liquid $\times$ volume of object = $1 \times 1 = 1 \, \text{kg}$.Upthrust = weight of displaced liquid = $1 \times 10 = 10 \, \text{N}$.Apparent weight = actual weight $-$ upthrust = $20 \, \text{N} - 10 \, \text{N} = 10 \, \text{N}$.Answer:The apparent weight is $10 \, \text{N}$.Correct option: B. 10N