Two rods of the same weight and equal length have different thickness. They are held vertically on the surface of sand as shown in Fig.11.9. Which one of them will sink more? Why?

Rod B will sink more because:

i. As we know that the smaller the area, larger the pressure on a surface for the same force applied.

ii. Rod B has a smaller area.

iii. Hence, it will exert more pressure on the sand.

iv. On the other hand, rod A will exert less pressure on the sand as it has a larger area.