Chapter 14.2, Problem 16R

To determine

The description of lifting the roofs from the building in tornados by using Bernoulli’s principle.

Explanation of Solution

Introduction:

Bernoulli’s principle governs the flow of the fluid between different positions. The total energy at a point remains conserved in the flow of fluid. The total energy includes kinetic energy, potential energy and pressure energy.

The potential energy of the fluid at the same elevation remains the same. So, it does not vary at the same height. The pressure energy depends on the pressure and kinetic energy depends on the speed of the fluid.

The pressure of air at a point and speed of the air varies inversely. If the pressure increases then the speed of the air decreases and vice-versa.

When air flows with high speed above the roof of the building, the pressure above the roof becomes less than the pressure below the roof. This pressure differential produces a lift force in upward direction and roof lifted off from the buildings.

Conclusion:

Thus, the roof lifted off from the buildings in tornados due to pressure differential between the above and below the roof.