Question

Atmospheric pressure is caused by the weight of a column of air above you, pushing down. At sea level on earth, this pressure is equal to 10^5 newtons per square meter. Answer the following:

a. Estimate the total force on the top of your head from this pressure.
b. Recall that the acceleration due to gravity is 9.8 m/s^2. If the force in part a were caused by a kangaroo sitting on your head, what would the mass of the kangaroo have to be?
c. Assume a typical kangaroo has a mass of 60 kg. How many kangaroos would have to be sitting on your head to be equal to the extremely massive kangaroo in part b?
d. Why are you not crushed by this astonishing force on your head?

Answer 1

The total force of atmospheric pressure on the top of a person's head is about 10,000 newtons. The equivalent mass of a kangaroo exerting this force would be roughly 1020 kg. Due to internal body pressure and evolutionary adaptation, humans are not crushed by this external pressure.

Step-by-step explanation:

Atmospheric pressure is the force exerted by the weight of the air above us. At sea level, this pressure is approximately 105 newtons per square meter (101 kPa).
a. The total force on an average adult head (which has an area of about 0.1 m2) would be 104 newtons, based on atmospheric pressure exerted on the surface area of the head.

b.Using acceleration due to gravity (9.8 m/s2), the mass of a kangaroo that would exert a force of 104 newtons would be 104 N divided by 9.8 m/s2, which is approximately 1020.41 kg.

c. If a typical kangaroo has a mass of 60 kg, about 17 kangaroos (1020.41 kg divided by 60 kg) would be needed to exert the same force as atmospheric pressure on your head.

d. You are not crushed by this force because your body is internally pressurized to balance the external pressure, and we are adapted to live under such conditions.