Question

The image shows force vectors acting on a submerged block. Since pressure increases with depth, is there more pressure acting on the bottom block? Is there a larger net force on the bottom block? Explain.

Answer 1

As depth increases, pressure in a fluid increases.So, more pressure is acting on the bottom block.

However, net force remains the same. According to Archimedes' principle, net force is equal to buoyant force which is equal to weight of displaced liquid. Since the weight of displaced liquid is same for both cases, the net force acting on the block is same for both cases.

In terms of pressure, note that the lower surface of the block experiences upward force, while upper surface of the block experiences downward force. With increase in depth, pressure has increased for both upper and lower surfaces of the bottom block and the net force( equal to force on lower surface minus force on upper surface) remains the same.