Difference Between Contact and Non- Contact Force

Introduction

Imagine you're sitting on a chair right now. You may believe that you are simply sitting and doing nothing. Yet, a slew of forces is at work against you!

Force is essentially a push or pulls on an object. It causes an object to move, change direction, or change speed. Even when you're sitting still, forces are acting on you. The force of gravity, for example, keeps you stuck to the ground instead of floating off into space!

But there are other forces at work as well. The chair you're sitting on is pushing up on you with force called the normal force. Your body also exerts a force on the chair, known as your weight. And if you were to lean to one side, you'd be applying a force to the chair in that direction.

Forces are constantly present all around us. While you walk, your muscles work hard to push your body forward. A ball is thrown through the air when you toss it by exerting force. And when you turn on a light switch, you're using a force to complete the circuit and light up the bulb.

Here we saw different forces we are encountering daily; now, let's move to the discuss and explore what this force is.

What is Force?

Force is a physical quantity that describes the push or pulls on an object resulting from the interaction between that object and another object or system. It can cause an object to accelerate, change direction, or deform and is measured in units of Newtons (N) in the International System of Units (SI).

The direction and magnitude of a force depend on factors such as the mass and velocity of the object, as well as the nature of the objects or systems involved in the interaction.

Force is a fundamental concept in physics and is essential for understanding a wide range of phenomena, from the motion of planets in space to the behavior of particles at the atomic level.

Contact and Non-Contact forces

Think about a time when you played tug-of-war with your friends. In that game, you were applying a contact force to the rope. Contact forces occur when two items come into physical contact with each other. Friction, tension, normal force, and air resistance are all contact forces.

For example, friction is a contact force when two items rub against one another. If you try to slide a heavy box across the floor, you'll feel friction pushing back against you, making it harder to move the box. Tension is another contact force when you pull on something, like the rope in a tug-of-war. And normal force is the force that keeps you from falling through the floor when you stand or sit on it.

Let us now discuss non-contact forces. These forces act on items that have no physical interaction with one another. Gravity, magnetic force, and electric force are examples of non-contact forces.

Gravity, for example, is a force that exists between any two objects that have mass. It keeps us and everything else on Earth from floating into space. The magnetic force is another non-contact force you might be familiar with if you've ever played with magnets. And electric force is the force that causes charged particles to attract or repel each other.

What is Contact Force?

Contact force is a sort of force that occurs when two things make physical touch with each other. It results from the interaction between the molecules or atoms of the objects and can cause changes in the motion or shape of the objects involved.

Contact forces are a fundamental concept in physics and are crucial for understanding the behavior of objects in the world around us. By understanding the nature of contact forces, we can gain insights into how they affect our everyday lives and the world around us.

What is Non-Contact Force?

A non-contact force acts on an object without the need for any physical contact between the object and the source of the force. These forces arise from interacting with objects through electric, magnetic, and gravitational fields. Non-contact forces can be attractive or repulsive, and they can act over a distance without the need for any physical contact.

Examples of non-contact forces include:

• Gravity: Gravity is a non-contact force between any objects with mass. It is responsible for holding planets in their orbits around stars, keeping moons in orbit around planets, and keeping objects on the Earth's surface.
• Electromagnetic force: A non-contact force between electrically charged particles is known as electromagnetic force. It is responsible for the behavior of magnets, the electric fields surrounding charged particles, and the interactions between electrically charged things. It can be attractive or repulsive.
• Nuclear force: Nuclear force is a non-contact force that holds together the particles in the nucleus of an atom. It is one of the strongest forces in nature and is responsible for keeping the nucleus stable.

Non-contact forces are an essential part of our universe and play a vital role in the behavior of objects, from the largest galaxies to the smallest subatomic particles. Understanding the nature of non-contact forces is crucial for physicists and scientists to understand the universe's workings.

Types of Contact Force

1. Normal force: The normal force is a contact force that acts perpendicular to the surface of an object. The "normal" force is so named because it is perpendicular to the surface or "normal" to it.

When an object is put on a surface, such as a book on a table, the weight of the object produces a downward force, while the surface exerts an equal and opposite upward force. This upward force is typical because it prevents the item from falling through the surface.

The normal force has the same magnitude as the force pushing down on the surface, which equals the object's weight. Newton's third law of motion asserts that every action has an equal and opposite response.

It is vital to notice that the normal force occurs only when the item touches the surface. When you hold a book in your hand, the normal force from your hand balances the weight of the book, but there is no normal force from the table or any other surface.

Another key notion is that additional forces operating on the item might influence the normal force. Pushing down on a book on a table, for example, increases the force pressing down on the surface, thereby increasing the magnitude of the normal force. Understanding how things interact with surfaces requires a grasp of the normal force. It is critical in many fields of physics and engineering because it lets us anticipate how objects react in different situations.

2. Friction Force: The friction force is the force that resists motion between two in-contact surfaces. It is caused by the surfaces' tiny roughness, which can interlock and prevent motion. Friction force acts in the opposing direction when an item moves. When an item is at rest, friction force works in the opposite direction as the force that would cause it to move.

There are two types of friction force:

I. Static friction: Static friction is the force that prevents motion from starting between two stationary surfaces. In other words, the force prevents a stationary item from moving.

The most significant magnitude of static friction force equals the force used to move the item. This indicates that if you push an item with less force than the maximum static friction force, it will not move.

The item begins to move when the applied force surpasses the maximum value of static friction force.

For example, you must use a force more significant than the maximum static friction force to move a heavy box down a floor. The force necessary to keep the box going is less than required to start moving.

II. Kinetic friction: Kinetic friction is the force that opposes motion between two surfaces in contact while one of the surfaces is already moving. It works in the opposite direction of the motion.

Kinetic friction is the force necessary to maintain an item moving at a constant speed. For example, when you slide a book across a table, the kinetic friction force between the book and the table resists the book's motion.

The quantity of static and kinetic friction force is determined by the type of the surfaces in contact, the force forcing the surfaces together, and the surface roughness.

Lubricants such as oil or grease can be employed to minimize friction force. Lubricants form a coating between two surfaces, minimizing direct contact and friction forces.

The materials determine the friction force in contact, the roughness of the surfaces, and the amount of force applied to the surfaces. A rough surface, for example, has more friction than a smooth surface, and a heavier object has more friction than a lighter thing.

Friction force may be helpful as well as damaging. On the one side, friction force enables humans to walk, run, and drive on the ground. On the other hand, the friction force can create wear and tear on machinery and make it more challenging to move big things.

3. Tension Force: Tension force is created when a string, rope, or cable is drawn taut between two objects. A simple experiment can help us understand tension force:

• Take a piece of string or rope and tie one end to a stationary object, like a doorknob.
• Pull the other end of the thread away from the fixed item. You will experience resistance to your pulling effort. This is the force of tension. When you pull the string harder, you will see that the tension force rises. This is because the tension force is proportional to the force applied to the string.
• You can also see how the tension force is communicated to the immovable item via the string or rope. Because of this, the doorknob resists your pulling effort.

Tension force is essential in many fields, including physics, engineering, and construction. For example, the tension force is used in suspension bridges, where cables support the bridge's weight under tension. Tension force is also used in the construction of buildings, where steel cables are used to reinforce concrete structures.

4. Spring Force: Spring force is a contact force that arises when a spring or elastic material is compressed or stretched. Springs are objects designed to deform under pressure and then return to their original shape when the pressure is released.

To understand spring force, you can try a simple experiment at home.

• Wrap a rubber band or a spring around your fingers. When you stretch or compress the rubber band or spring, you will sense a force resisting your movement.
• This is the spring force at work.
• The spring force exerted is determined by how much the spring is compressed or extended and the spring's stiffness. More force is required to compress or extend stiff springs than more flexible springs.

Another example of spring force can be seen in a car's suspension system. The car's suspension system comprises springs designed to absorb the shock of bumps in the road. When the car hits a bump, the springs compress and then push back against the force of the bump, creating a smoother ride for the passengers inside.

5. Air Resistance Force: Air resistance force, often known as drag force, is a force that resists an object's motion through the air. When an item goes through the air, it collides with air particles, which create a resistance force that slows the object's velocity.

The amount of air resistance force experienced by an item is determined by various parameters, including the object's size, shape, and speed, as well as the density and viscosity of the air. To understand air resistance force, you can perform a simple experiment.

• Take a piece of paper and crumple it into a ball.
• Hold the ball at the top of a stairwell and drop it.
• Notice how the ball falls slowly and gently to the ground. This is because the crumpled paper ball experiences air resistance force, which slows down its motion and reduces its speed.
• Now, hold a flat piece of paper horizontally in front of you. Blow on the paper and notice how it moves away from you. This is because the air resistance force pushes the paper away from you in the opposite direction of your breath.

In everyday life, we can experience air resistance force while riding a bicycle or driving a car. The faster we move, the greater the air resistance force we experience, which makes it harder to move faster. This is why cars and bicycles have aerodynamic designs that reduce air resistance and make it easier to move faster.

Understanding air resistance force is essential in fields such as aviation, where engineers design airplanes with streamlined shapes and powerful engines to overcome air resistance and achieve high speeds.

6. Buoyant Force: The buoyant force is a type of contact force that arises when an object is submerged in a fluid, in this case, air. The force is exerted on the object in the upward direction, equal to the weight of the displaced air. This means that the denser the object is, the greater the weight of the air it will displace and, therefore, the greater the buoyant force it will experience.

To see this in action, you can try an experiment at home.

• Take a balloon and blow it up.
• The air inside the balloon has a lower density than the air outside, so when you let go of it, it will float upwards due to the buoyant force.
• Now, take a piece of paper and crumple it up into a ball. This ball is denser than the air around it, so it will not experience as much buoyant force as the balloon and will fall downwards instead of floating upwards.

Types of Non-contact forces

1. Gravitational force: Gravitational force is an elemental force between all objects with mass in the cosmos. It is an attracting force that draws items together. The gravitational force's strength is proportional to the mass and distance between the objects. The stronger the gravitational pull, the greater the mass of the items and the closer they are.

This force maintains the planets in orbit around the sun, the moon in orbit around Earth, and all objects on Earth from drifting away into space. It is a tremendously powerful force in the cosmos since it directs the motion of celestial bodies and plays an essential part in defining the universe's structure. Consider a flattened rubber sheet to represent the notion of gravitational force. Placing a hefty object in the center of the sheet will cause it to distort and bend. Because of the curvature of the sheet, if you lay a smaller object nearby, it will roll towards the more significant thing. It is comparable to how gravitational force operates between two things. One object's mass warps the fabric of space-time, causing a curvature that affects the velocity of other things nearby.

The universal law of gravitation describes the gravitational force quantitatively, stating that the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. It indicates that as the distance between two things grows, so does the gravitational force between them.

The gravitational force is an intriguing and vital subject to understand while studying physics and astronomy. It significantly influences the mobility and behavior of things in the cosmos. It is a topic of continuing inquiry and exploration.

2. Electric force: Electric force, or electrostatic force, is a fundamental natural force resulting from electrically charged particles' interaction. Together with the strong nuclear force, the weak nuclear force, and the gravitational force, it is one of the four fundamental forces in the universe.

Electric forces cause the attraction or repulsion of electrically charged particles. Similar charges repel one another, whereas opposing charges attract one another. This force connects atoms and molecules and is used in electrical devices.

Coulomb's law says that the force between two point charges is proportional to the product of their charges and inversely proportional to the square of the distance between them. This is stated mathematically:

F = k * q1 * q2 / r^2

Where F is the force, q1 and q2 are the charges of the two particles, r is the distance between them, and k is the Coulomb constant, which is a fundamental constant of nature.

Several ordinary phenomena exhibit electric force, such as when you brush a balloon against your hair, and it adheres to a wall or when you get an electric shock after walking across a carpet and hitting a doorknob. The electric force also controls electronic gadgets such as computers, cell phones, and televisions.

The electric force is a fundamental natural force that governs the attraction or repulsion of electrically charged particles. It is measured by Coulomb's law and is essential for binding atoms and molecules together and operating electrical equipment.

3. Magnetic Force: A magnet or a magnetic field exerts a magnetic force on a magnetic substance. This force is capable of attracting or repelling other magnets or magnetic materials.

Magnetic materials feature magnetic domains at the atomic level, which are groupings of atoms with magnetic fields pointing in the same direction. When these materials are subjected to an external magnetic field, the magnetic domains align with the external field, leading the material to become magnetized.

The strength of the magnetic force is determined by various parameters, including the strength of the magnetic field, the distance between the magnets or magnetic materials, and their orientation relative to each other.

Magnetic force, like gravity and electromagnetic force, is an elemental force of nature. It is essential in many sectors of contemporary technology, like power generation, electric motors, MRI machines, etc.

Imagine two bar magnets with opposing poles facing each other to illustrate the magnetic force. When the magnets are brought near together, the north pole of one attracts the south pole of the other, while the south pole of one repels the north pole of the other.

The Lorentz force equation, which says that the force on a charged particle traveling in a magnetic field is proportional to the particle's velocity, the intensity of the magnetic field, and the particle's charge, may be used to describe the magnetic force. This equation is critical for understanding the behavior of charged particles in magnetic fields, such as those found in particle accelerators.

The magnetic force is an intriguing and fundamental part of physics essential in many current technologies.

4. Nuclear force: So, what exactly is nuclear force? The nuclear force is a strong force between protons and neutrons, the particles that make up an atom's nucleus. It is similar to the force that keeps you and me together when we hug. Because of their electromagnetic charge, positively charged protons in the nucleus of an atom would ordinarily repel each other. However, the nuclear force operates between them to counteract this repulsion, allowing the nucleus to remain stable.

The nuclear force is quite powerful. It is several orders of magnitude more powerful than electromagnetic force. This is because the force is transmitted by particles known as mesons, which are transferred between nuclei. This exchange produces a force that holds the nucleons together and maintains the stability of the nucleus. The nuclear force has a relatively small range, only a few femtometers. This means it can only act across minimal distances, often within the range of the nucleus's size.

Let us now consider the relevance of nuclear weapons. Without the nuclear force, the positively charged protons in the nucleus would naturally oppose each other, resulting in the nucleus splitting apart, radioactive decay, and the emission of hazardous radiation. As a result, nuclear force is required for stable atoms. Additionally, nuclear force is essential in various important nuclear physics events, such as nuclear fusion and fission.

Nuclear fusion is the process of two atomic nuclei joining to produce a heavier nucleus, which releases energy and powers the sun and other stars. Nuclear fission breaks a heavy nucleus into two lighter nuclei, often releasing additional neutrons and energy employed in nuclear power plants and weapons. Since the nuclear force is critical in maintaining the nucleus together and enabling stable atoms, it is a unique and critical force in many important nuclear physics events.

5. Radiation pressure force: Radiation pressure, or radiation pressure, is a physical phenomenon that occurs when electromagnetic radiation interacts with objects and exerts pressure on them. This phenomenon results from the momentum transfer from photons, the constituent particles of electromagnetic radiation, to the objects they collide with.

The radiation pressure force is proportional to both the intensity of the radiation and the surface area of the object it impinges upon. Hence, as the intensity of the radiation and the area of the object increase, the force of radiation pressure also increases accordingly.

Examples of Radiation Force

1. One of the most notable illustrations of radiation pressure force is observed in solar sailing. This technology harnesses the pressure exerted by the sun's radiation to propel a spacecraft forward. The sail comprises a lightweight material with a large surface area that captures the energy from the sun's photons and converts it into momentum, thereby driving the spacecraft forward.
2. Overall, the radiation pressure force is a fascinating physical phenomenon that finds numerous applications in different fields of science and technology. From solar sailing to optical manipulation, its diverse applications inspire research and exploration.
3. Another example of the radiation pressure force can be seen in the formation of comet tails. When a comet approaches the sun, the heat causes the ice and other materials on the comet to sublimate, releasing gas and dust particles into space. The radiation pressure force pushes these particles away from the sun, creating the characteristic tail we see behind a comet.

In addition to these examples, the radiation pressure force has also been studied extensively in optics. In this context, the force of radiation pressure is used to manipulate tiny particles and molecules, allowing scientists to study their properties and behavior.

Therefore, radiation pressure force is a fascinating physical phenomenon that plays a role in many different areas of science and technology. This force has many applications, from solar sailing to comet tails to optical manipulation. It continues to be the subject of ongoing research and studies.

Conclusion

Contact forces are those forces that require physical contact between two objects. In comparison, non-contact forces are those forces that act without any physical contact between two objects. Examples of contact forces include frictional, tension, and regular forces, while non-contact forces include gravitational, magnetic, and electrical forces.

One of the critical differences between contact and non-contact forces is that contact forces are typically weaker than non-contact forces, as they rely on the strength of the materials in contact to exert a force. Non-contact forces, on the other hand, can act over long distances and are often much more potent than contact forces.

Another critical difference is that contact forces only act when two objects are in direct physical contact. In comparison, non-contact forces can act even when there is no physical contact between two objects. This is because fields such as gravitational or electromagnetic fields mediate non-contact forces.

Overall, understanding the differences between contact and non-contact forces is essential in many areas of science and engineering, as it can help us to design more efficient and effective systems and technologies.