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TOPIC 16: Physics of Fluids

Tip 1:

How do you answer this question: Explain how a plane's wings are able to create a lift force.

Some model answers wrote about Bernoulli's Effect, ie. the air flow over the top of the wing is faster than that below. Therefore according to Bernoulli's equation, the pressure will be higher at the bottom than the top, thus creating a lift force.

But some other answers said that the downward momentum of the air stream created an equal and opposite force that resulted in an upward lift on the plane (by Newton's Third Law - Action/ Reaction Law).

So which answer is correct? In my opinion, they're just different ways of looking at things.

In fact, there is a "battle" going on amongst scientists and engineers whether it is the Bernoulli effect or the Angle of Attack/ Newton Dynamics that created this lift force.

We shall not get ourselves drawn into this battle. Since this chapter is on the Bernoulli effect, let's support Mr. Bernoulli. Until one day you become an engineer you may choose to support another party.