Pressure and Motion: Types, Examples and Everyday Applications

Pressure and motion are two important concepts in physics that explain how forces act on objects and how objects move from one place to another. Have you ever wondered why trucks have wide tyres or why a balloon expands when it is inflated? Similarly, have you noticed the movement of a pendulum or the hands of a clock? All these events can be explained using the concepts of pressure and motion.

Table of Contents

• What is Pressure
• Examples of Pressure in Daily Life
• Pressure Exerted by Liquids and Gases
• Atmospheric Pressure
• What is Motion and Different Types of Motion

What is Pressure

Pressure is an important physical quantity that explains how force acts on a surface. In our daily lives, we experience pressure in many ways, such as cutting vegetables with a knife, carrying a school bag, or inflating a balloon. The amount of pressure depends not only on the force applied but also on the area over which the force acts.

Pressure is defined as the force exerted per unit area. It depends on two factors: force and area.

If the exerted force is high, the pressure will also be increased. When a force acts over a large area, pressure will be less, whereas pressure will be high if a force acts over a small area.

Pressure is directly proportional to force and inversely proportional to area.

The mathematical formula of pressure is,

Pressure = Force ÷ Area

or

P = F/A

The SI unit of pressure is the pascal (Pa).

Examples of Pressure in Daily Life

Pressure plays an important role in many activities around us. By changing the area of contact or the force applied, we can increase or decrease pressure according to our needs.

Why do trucks and tractors have wide tyres?

Trucks and tractors have wide tyres because they have a large area, so less pressure is exerted on the ground.

Tractors are used in agricultural fields because, due to the reason mentioned above, the tyres do not sink into the soil.

Similarly,

• Hammering a sharp nail is easier.
• School bags with wide straps create less pressure on our shoulders.
• A sharp knife can cut better than a dull knife.

More Examples of Pressure Around Us

• Snow shoes have a large surface area, preventing a person from sinking into the snow.
• Camels have broad feet, which help them walk easily on sand.
• Pins and needles have sharp pointed ends so that they can exert greater pressure.

Pressure Exerted by Liquids and Gases

Both liquids and gases are fluids and exert pressure in all directions. The pressure produced by a fluid depends on factors such as depth, temperature, and volume.

Pressure Exerted by Liquids

The molecules of a liquid exert pressure in all directions. The liquid molecules exert pressure on the walls of the container in which they are poured.

The intensity of sideways pressure increases along with the depth of the container. The liquid molecules also exert pressure at the bottom of the container.

The pressure on the bottom of the container increases as the height of the liquid increases in the container.

Why Does Liquid Pressure Increase with Depth?

As we move deeper into a liquid, the amount of liquid above increases. Therefore, the weight of the liquid becomes greater, resulting in greater pressure.

This is why divers experience higher pressure underwater.

Pressure Exerted by Gases

Gas molecules also exert pressure in all directions like liquids. Gas can be compressed in a container.

When a balloon is inflated, it becomes bigger due to the pressure of the gas molecules, whereas a deflated balloon shrinks and has little or no gas inside it to put pressure on its walls.

The pressure exerted by gas molecules increases when the temperature increases and decreases when the temperature decreases. The volume of the gas increases when pressure is low and decreases when pressure is high.

We can say that the pressure exerted by a gas is directly proportional to temperature but inversely proportional to volume.

Why Do Gases Exert Pressure?

Gas molecules are in continuous random motion. They constantly collide with the walls of the container, and these collisions produce pressure.

Atmospheric Pressure

The Earth is surrounded by a layer of air called the atmosphere. The weight of this air exerts a force on everything around us, and this force is known as atmospheric pressure.

We all know that gravity pulls air towards the Earth. So, we can say that atmospheric pressure or air pressure is the force exerted by the air around us.

Air pressure also acts in all directions.

Importance of Atmospheric Pressure

• It helps us breathe.
• It influences weather and climate.
• It allows drinking through a straw.
• It plays an important role in the working of syringes and pumps.

What is Motion and Different Types of Motion

Motion is one of the most common phenomena observed in nature. From the movement of vehicles on roads to the revolution of planets around the Sun, everything around us is in motion.

The phenomenon of an object moving or being moved is called motion. Force can initiate the movement of an object as well as it can stop a moving object.

Different Types of Motion

Objects can move in different ways depending on the path they follow. Based on the nature of movement, motion can be classified into different types. 

Rectilinear Motion

When motion occurs in a straight line, it is called linear motion.

Example: Motion of a man running.

Circular Motion

When motion occurs in a circular path, it is called circular motion.

Example: Motion of the minute hand of the clock.

Rotational Motion

When motion occurs in a rotational path, it is called rotational motion.

Example: Motion of a soccer ball in a soccer match.

Periodic Motion

When motion occurs in a periodic path, it is called periodic motion.

Example: Motion of a simple pendulum.

Uniform Motion

When a body travels equal distances in equal intervals of time, it is called uniform motion.

Non-Uniform Motion

When a body travels unequal distances in equal intervals of time, it is called non-uniform motion.

In this concept, we have learned that pressure is the force exerted per unit area and depends on force and area. We also understood that liquids, gases, and air exert pressure in all directions. Further, we studied different types of motion such as rectilinear, circular, rotational, and periodic motion, along with uniform and non-uniform motion.