AAA estimates that, every year, more than 10,000 drivers swerve off the road and

ID: 1860767 • Letter: A

Question

AAA estimates that, every year, more than 10,000 drivers swerve off the road and end

up submerged in water. This terrifying scenario can be life-threatening, as the water

pressure exerted against a sinking auto makes it extremely difficult to open a door and

swim to safety.

In a MythBusters episode Jamie Hyneman and Adam Savage took the plunge to verify

the scientific logic that until a car completely fills with water and equalizes the pressure

inside and outside it.

As an engineer you can investigate this without having to sink a car, in a pool (though

that might be more fun). Assume that the car sinks straight down with the front end first

(i.e. car oriented vertically). Note this is different from the MythBusters who sank their

car oriented horizontally. Calculate what at what depth a person will no longer be able to

open the door of their vehicle while the passenger compartment is still filled with air.

This question is highly open-ended. You will need to make assumptions to make the

problem tractable. Justify your answer, including any assumptions that you need to make

in order to solve the problem.

let volume of car is 100 m^3

pressure of air inside car is 1 atm

area of car door is 1 m^2

let depth at which a person will no longer be able to

open the door of their vehicle while the passenger compartment is still filled with air is H

pressure exerted by person on door is 10 atm

density of water * acceleration of gravity * H * 1 = (1 + 10)*1

H = 11/9.81 aym.m.s^2/kg