A block of wood is initially floating in a lake at 4°C with 20% of the block exposed abo...

A block of wood is initially floating in a lake at 4°C with 20% of the block exposed above the surface of the water (Fig. 10.20). The temperature of the water then increases to 20°C. Will the block move (a) up or (b) down relative to the surface of the water?

(reference figure 10.20)