Question

Assume a force of 30 N is distributed over a surface of area 2m^2 in such a way that at each point force can be considered to act at an angle of 30° to the normal at that point. What will be the value of pressure on that plane?

(a) 7.5 Pa

(b) 7.5\(\sqrt{3}\) Pa

(c) 15 Pa

(d) 15\(\sqrt{3}\) Pa

This question was posed to me in unit test.

I need to ask this question from Fluids Mechanical Properties Pressure in chapter Mechanical Properties of Fluids of Physics – Class 11

Answer 1

Right option is (b) 7.5\(\sqrt{3}\) Pa

To explain I would say: One important thing to keep in mind is that pressure at a point is the normal component of force per unit area, NOT total force per unit area.

So, here we will take the normal component of 30N force, i.e:

30cos(30°)=15\(\sqrt{3}\).

Press = F/A = 15\(\sqrt{3}\)/2

= 7.5\(\sqrt{3}\) Pa.