Bernoulli's Principle

Common Applications of Bernoulli's Principle 

Bernoulli's Principle has common  several various modern day applications in the world around us. The following section discusses where, and in what applications can you see this principle take place.


One of the most common everyday applications of Bernoulli's principle is in airflight. The main way that Bernoulli's principle works in air flight has to do with the architecture of the wings of the plane. In an airplane wing, the top of the wing is soomewhat curved, while the bottom of the wing is totally flat. While in the sky, air travels across both the top and the bottom concurrently. Because both the top part and the bottom part of the plane are designed differently, this allows for the air on the bottom to move slower, which creates more pressure on the bottom, and allows for the air on the top to move faster, which creates less pressure. This is what creates lift, which allows planes to fly. An airplane is also acted upon by a pull of gravity in which opposes the lift, drag and thrust. Thrust is the force that enables the airplane to move forward while drag is air resistance that opposes the thrust force.


One of the most common trends that occurs in the modern day physics world is that of lift. Lift can be seen in many different ways, shapes, and forms in our world. Lift is seen in airflight, as in my example above, as well as in several of my forthcoming examples. But , what is lift exactly? Most people define lift in terms of Bernoulli's principle which has some validity to it, but the main way for one to define lift is through Newton's three laws. While most accept that Bernoulli's principle is what creates lift, some say that it leaves many unanswered questions. For one, it says that upside down flight cannot happen. Also, many people say that by using Bernoulli's principle to explain lift, it doesn't take into account the fact that no where in the commonly accepted defenition of lift, is there any mention of work, and lift can only take place if there is a certain type of unit of work that we are all familiar with, called power. The next most widely accepted definition of lift involves Newton's three laws, specifically his first and third. (The first is the law of intertia and the third is that for every acton there is an equal and opposite reaction.) As we have all seen on an airplane, the wing moves up and down a little bit as it flies through the air, but under the common defintion of lift, this cannot happen; the wing just stays still. Many physics scholars believe that there must be some form of movement on the object that is being lifted. Some believe that according to Newton's law "the wing must change something of the air to get lift. 


Baseball Baseball is an example of where Bernoulli's principle is very visible in everyday life, but rarely do most people actually take note of it. One example in baseball is in the case of the curve ball. The entire pitch works because of Bernoulli's principle. Since the stitches of the ball actually form a curve, it is necessary for the pitcher to grip the seams of the baseball. The reason as to why this is a necessity is that by gripping the baseball this way, the pitcher can make the ball spin. This allows for friction to cause a thin layer of air to engilf the misunderstanding of the baseball as it is spinning, but since the ball is spinning in a certain manner, this allows for more air pressure on the top of the ball and less air pressure on the bottom of the ball. Therefore, according to Bernoulli's principle there should be less speed on the top of the ball than there is on the bottom of the ball. What transpires is that the bottom part of the ball accelearates downwards faster than the top part, and this phenomenon allows for the ball to curve downward, which causes the batter to miscalculate the ball's position.


And furthermore, another example of Bernoulli's principle in our everyday lives is in the case of someone feeling a draft. We all at at least one time or another, have experienced feeling a draft, and it is because of Bernoulli's principle that we feel this draft. Let's say that in your room, you are really hot, but you know that it is nice and cool both outside your window and outside your door. If you open up your window, to try and let fresh air in, there won't be much of a temperature change, unless the door to your room is open to air out the hot air. The reason why it works this way is that if the front door is closed the door will become an area of high pressure built up from the hot air, and right outside the door there is little pressure, meaning that the rate at which the air enters will be in an incredibly high speed. When you open the door, the pressure is relieved from the door on the inside and the hot air exits quickly. When the hot air exits there is a lot more pressure outside meaning that it will take awhile for the cool air to come in. Once the hot air has flown out, the cool air will come in at a fast speed, thus causing a draft.


In addition to the three items above, Bernoulli's principle is also the governing theory that is behind sailing. Most people believe that sailing is just having a big sail and that when you put it up, the wind just takes your boat and drags it along the sea. This is not 100% correct. This is true only in the cases when the boat is moving with the wind, otherwise it is not true. When the boat does not travel with the wind, it usually moves perpendicular to the wind, and the boat moves not because the wind drags it along, but because of the concept of lift, which as mentioned above and in the case of airplanes, is what happens when either a liquid or a gas act on an object. The same way that Bernoulli's principle works for creating lift in airplanes, it works for creating lift in sails. All sail boats have two parts to it: a sail which points north and a keel which points on the opposite direction. If the speed of the air increases on the sail, there is less pressure on the sail, and conversely there is less pressure on the keel but a higher speed. Just like with an airplane this produces lift and propels the sail to move in the water.