7 Examples Of Physics Pressure Phenomena In Real Life

“Pressure” - What comes to mind when you first hear the term?

When you’re dealing with Secondary 3 or 4 physics, you already have an idea of what pressure is. In the simplest terms, it’s defined as the force applied per unit area, which constitutes the basic formula:

P = F/A

You also know that you can change the amount of pressure by increasing/decreasing either the applied force or the area. Some common types of pressure that you may have come across and probably also written in your PSLEs, are atmospheric pressure, hydrostatic pressure, etc.

While some of the applications are solids, like a nail exerting pressure on a wooden plank, liquids and gases too exert pressure on the walls of containers that hold them.

Now, that was your primary science knowledge, i.e. the basics, which has helped build an intuition regarding pressure. You have learned that it’s a physical quantity depending on the amount of force and the application area. Secondary physics will delve deeper into the topic, helping you calculate pressure in diverse situations accurately.

• In sec 3 itself, you’ll be formally introduced to the topic, and
• In sec 4, you’ll no longer treat it as an independent entity.

Further, you’ll understand its application across various real life scenarios, besides calculating the amount.

At our secondary physics tuition in Singapore, we help build a foundation so strong that students rarely face difficulties solving problems or identifying the effect of pressure in diverse practical applications.

7 Pressure Phenomena That Impact Day-To- Day Activities

Before we start giving you the examples of some real life pressure phenomena and how those influence both regular and critical systems, you can check out some sample questions on pressure to get an idea of what to expect in your exams.

1. Flat Shoes Vs High Heels

One of the most common examples of pressure phenomena that we teach at our sec 3 physics tuition is the comparison between high heels and flat shoes.

Have you noticed how high heels penetrate soft grounds, like mud or sand, making it difficult to stand or walk? Why do you think this happens?

In both cases, the amount of force applied may be the same, i.e. the bodyweight of the wearer while walking or standing. However, what changes is the area on which that force is applied.

For example,

• A person weighs 500 N and the heel area measures about 0.0005 m².
• On applying P = F/A, we see that the pressure amounts to 1,000,000 Pa.

The same force applied on a flat shoe with the underneath area of 0.02 m², amounts to 25,000 Pa, about 4 times lower than that of high heels.

This is the reason why walking or standing with high heels on soft ground causes the wearer more difficulty than in flats.

This practical scenario also applies to pencil heels and platform heels. While the former poses a greater difficulty to wearers, the latter gives greater comfort and balance.

2. Sharp Knives Vs Blunt Cutting Tools

Now the same theory applies for sharpened knives and cutting tools versus blunt ones. In sharp knives, the area at the edge is smaller. When pressure is applied, it penetrates materials faster. The same pressure applied on a blunt cutting tool is spread over a wider area, making it harder to cut.

So be it a kitchen knife, surgical tools, or smaller items, like nails and pins, the sharper it is, the faster it will cut.

Note: In butter knives, the edge area is deliberately made wider, so it penetrates softer surfaces like cake or butter easily but cannot do the same for harder materials, e.g., a watermelon skin.

3. Drinking Liquids Through Straws

This one’s a little different from the two aforementioned examples, as it debunks a common myth -

Through suction, you can pull liquids readily.

The fact is, you don’t first suck the liquid upwards into your mouth. It happens in three distinct phases.

• You suck the air out of the straw,
• The air pressure around it forces the liquid to fill the vacuum
• And the liquid gets sucked into your mouth.

At our physics tuition in Bukit Timah, Singapore, we also tend to clear such scientific misconceptions that many students tend to carry forward. Our goal is to make scientific concepts both understandable and accurate to develop strong foundations.

4. The Function Of Suction Cups

Like the straw phenomena, suction cups also follow the pressure difference principle. When you press such cups against a flat, smooth surface, the force applied causes the air to move out from that area, creating some kind of vacuum.

With the atmospheric air pressure in the surrounding space being higher, it pushes the cup firmly against the surface before it starts returning to its original form. It shows clearly that even the air around us exerts a decent amount of pressure.

5. Liquid Pressure Increases With Depth

One of the most interesting things that a physics tutor will help you understand in secondary 3 is how liquid pressure rises with depth.

Have you observed how dams are built thicker near the bottom? Or do you wonder why deep sea divers often feel some kind of discomfort in their ears?

It’s all because liquid pressure is greater in depth than at the surface.

As you go deeper, the layers of liquid above will exert a considerable amount of pressure in addition to the atmospheric pressure. This explains why holes created horizontally in a container filled with liquid, say water, produce water jets at different ranges. The ones spurting out from near the bottom area have a higher range than their peers above.

6. Hydraulic Jacks In Cars And Other Systems

The working of hydraulic systems is a clear example of how pressure is transmitted through liquids. These systems have enclosed liquids on which a certain amount of force is applied. The resultant pressure spreads evenly throughout the liquid, as it cannot be compressed.

But how does this pressure change, as we see in the case of hydraulic jacks that are able to lift lighter to heavy vehicles?

Many students assume that increasing the force will automatically increase the resultant pressure. But it’s not the case.

Every hydraulic jack is composed of these elements -

• A smaller piston
• A larger piston, and
• Enclosed liquid connecting them.

When you push the smaller piston (say of 0.002 m²) down with a force of 100 N, it creates a pressure of about 50,000 Pa.

As this pressure spreads out evenly throughout the system, at the larger piston, it delivers a greater force. How?

P= F/A

So, F= P X A

50,000 Pa (Pressure) X 0.02 m² (larger piston area) = 1,000 N (Force)

That’s the reason hydraulic jacks are able to lift both lighter and heavier vehicles using two different pistons.

7. Airplane Lifts And Flight

Now, this is quite a recurring question in many students’ minds, whether in primary or secondary levels.

How do airplanes fly?

While the flight of an airplane is not dependent only on one physical phenomena, our physics tutors can explain the contribution of air pressure in it.

The wings of the airplane actually hold the secret formula.

These are shaped in a way that forces the air above to travel faster than the air below. The air below the wing creates higher pressure as speed of air is indirectly proportional to pressure.This helps push the plane upwards, which is also known as the lift mechanism.

But this happens only when the plane is already moving. If it stops, the air stops flowing, the pressure difference will disappear and the lift will no longer be there.

Physics Is All Around Us And So Is Pressure

Now these examples of pressure phenomena clearly reveal how physics is woven into our daily lives, even in the minutest of activities. It’s not limited to some classroom or textbooks. From breathing, drinking, walking and running to traveling and working at a factory or diving under the sea, everything involves physical pressure, which you should learn to decipher.

Once you have the ideas clear and the concepts concrete, you can attempt any kind of tricky question in your O and A Levels and also solve problems easily.

At our physics tuition in Bukit Timah, Singapore, we always aim to clear concepts first, debunking misconceptions and demonstrating textbook theories with simple, hand-on experiments. Of course, we cannot show you the functioning of an airplane wing, but we can easily conduct the straw experiment or the heel vs flats one.

Contact Miracle Learning Centre today to know more about our flexible schedules for sec physics or combined science tuition for primary students. If you have queries, feel free to ask. We have all the time to resolve your doubts before we enroll your child in our batch. Just get in touch and everything else will fall in place.