Answer:
7.75 kg
Step-by-step explanation:
Archimedes’ principle tells you that the weight of the water displaced is equal to the buoyancy force:
To keep the wood afloat, the buoyancy force must have the same magnitude as the force of gravity on the block, so
The volume of water displaced is
So the mass of water displaced is
Thus, the mass of the piece of wood is 7.75 kilograms.