In which direction do fluids exert pressure?

The head of a pin is flat and thick whereas its tip is fine and thin. Explain why? Write a formula that support your answer.

OR

When you press the head of a pin, it pierces into the board and not your thumb. Why?

A hollow plastic ball is taken to the bottom of a trough of water and released there (see adjoining figure).

(a) What happens to the ball?
(b) Give reason for this phenomenon.