Question

a boy gets into a floating boat

(a) what will happen to the weight of the water displaced

(b) what will happen to the upthrust

Answer 1

When a boy get into the floating boat then the boat starts flowing lower into the water because the weight of the boat increases.

(1) As the boat keeps on floating therefor the weight of the water displaced is also increased because the weight of the boat is increased. The condition for the floatation is
$Weightofthebody=Weightofthedisplacedliquid$

(2) The upthrust also increases because when the objects floats into the water then the upthrust or the buoyant force acting upon the object is equal to the weight of the fluid displaced by the object. As, the weight of the displaced liquid is increased therefore the upthrust will also get increased.