Question

Gauge pressure in the fluid surrounding an infant's brain may rise as high as 73.5 mm Hg (5 to 12 mm Hg is normal), creating an outward force large enough to make the skull grow abnormally large.

(a)

Calculate this outward force in newtons on each side of an infant's skull if the effective area of each side is 72.4 cm².

N

(b)

What is the net force (in N) acting on the skull?

N

Answer 1

Consider the skull to be a six sided cube. All five faces or sides except the one which is connected to neck will be under same gauge pressure of 73.5 - 8.5 = 65 mm of Hg = 8665.96 Pa = ∆p.

So,

For each side, where A is the effective area of each face or side.

Hence, for each side, F = 8665.96 x 72.4 x (1/10000) N = 62.7415504 N .

Note:- Do not forget to convert the respective units.

Now,

The net force,

Thus, 62.74 N is acting on each side and 313.71 N is the net force on the skull.