lets say we have some sphere under some pressure and I want to find what is the force pressing one-half of the sphere toward the opposite half?,lets take one piece of area then the pressure force exerted in this area is:
$$p\Delta A$$
and the horizontal component is: $$p\Delta A cos\theta$$
book says the following:
A cos θ is the projection of the area ΔA on a vertical plane, i.e., it is the fraction of the area facing to the right, in silhouette. For the complete half sphere, the net area facing to the right is πR^2 and the net force toward the left is therefore pπR^2
I dont understand that statment.why the area is not onehalf of that, can someome offer me an intuitive explanation of what happen, why the net force to the left is pπR^2?