Daniel Bernoulli gave a basic principle of fluid dynamics, this principle helps us understand how an airplane flies, how a spinning ball curves, how a chimney functions, why a fast-moving train pulls things closer to it, etc. It’s an important principle of physics that makes us understand the phenomena occurring in our daily life. In physics, Bernoulli’s Principle states that when the velocity of flow increases, pressure decreases, and vice versa. Let’s have a few real-life examples of Bernoulli’s Principle:
1. How an airplane takes off?
When an airplane moves on the runway, the shape of the wings of airplanes is designed in such a way that the air flowing over the upper side of the wing has to cover more distance than the air flowing underneath at the same time. Hence, on the upper side of the wing, air velocity is higher than the lower side, and the pressure is lower on the upper side of the wing; making the aircraft take off when the air tries to move from higher pressure to lower pressure.
2. Why a fast-moving train pulls nearby objects?
The air close to a fast-moving train also moves in the direction of the train, and due to the higher velocity of airflow close to the train, a low-pressure zone is developed close to the moving train, and thus, the surrounding air rushes from high-pressure to a low-pressure area, and this is the reason that things are pushed towards the train. People standing on platforms are advised to move away and keep their belongings away from approaching trains to avoid accidents.
3. Why a spinning ball curves
When a ball is thrown with a spin, the ball moves against the surrounding air, but there is a portion of the ball spinning in the direction of the air, and its opposite part spins against the air. The relative velocity of air spinning in the direction of air becomes more, but in opposite direction, the spin of the ball opposes airflow, and the velocity of the air is relatively lesser. As per Bernoulli’s Principle, more air velocity leads to lesser pressure, and the air moves from high pressure to lower pressure area, which pushes the ball to a curved path.
4. Why roofs are blown away in heavy winds?
During heavy winds, the velocity of air is stopped by the walls of the house, but the velocity is very high on the rooftop, which creates a lower pressure zone on the rooftop, but inside the house, the air velocity is very less, and hence, the pressure is very high as compared to the rooftop. High-pressure air inside the room tries to move towards a low-pressure area, and hence, the roof is lifted and blown away sometimes.
5. How atomizer works?
If we see the diagram of the atomizer carefully, the pressure at point “A” and point “B” is the same under normal conditions. When rubber bladder “R” is squeezed, the air rushes from the nozzle at point “B,” and due to high air velocity, the pressure drops down, and fluid at point “A” rushes from high pressure to the low-pressure area and gets sprayed by high-velocity air at point “B.” The carburetor also works similarly.
6. How chimney works?
Wind velocity outside the house is normally higher than inside, due to higher velocity above the nozzle of the chimney, the pressure becomes low, and the air rushes from high pressure to a low-pressure area, and thus, the smoke is blown away by the chimney. Thus, we can easily understand why chimneys work better when there is high wind flow.