A wooden block of mass 0.8kg floats in fresh water with 20% of its volume above the water surface. Take density of water =1000kg m−3 and g=9.8m s−2.
(i) Calculate the volume of the block.
(ii) Using your result from part (i), determine the density of the wood.
(iii) Sand is gently poured on the upper surface of the block so that it remains horizontal and continues to float. Determine the minimum mass of sand that must be added so that the top surface of the wooden block just comes level with the water surface.
(iv) If an additional 0.1kg of sand is placed on the block after part (iii), state and explain whether the block–sand system will sink or continue to float.