Common Forces in Mechanics
When we study laws of motion, we deal a lot with common forces in mechanics. So, what are the different types of common forces of mechanics? A force is the change of state of an object due to external surroundings. Due to forces, an object will either be in a state of motion or will be resting. For example, consider a football placed on the ground motionless. To move the ball in any direction, you will have to apply some forces on the ball. In this case, you are applying a force to the ball with the help of your legs. Eventually, the ball will move in the intended direction. The common forces in mechanics can be classified into two main groups, that is contact forces and non-contact forces. In this article, we will look at different types of force class 8, and the electrostatic force definition for class 8.
Contact Forces
As the name suggests, we experience contact forces only when the two objects come in contact. Some of the common examples of contact forces are tensional forces, air resistance forces, and frictional forces. In contact forces, the energy is transferred from one object to another. Sometimes you can also notice contact forces when an object is immersed in liquid. We will now look at different types of contact forces.
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Spring Force
We all have seen and used spring in our lives. You must have noticed that it shrinks down when you apply force on one side of the spring. As soon as you release the force, the spring jumps back to its original state. Spring force is defined as the force that acts opposite to the displacement of the object.
Applied Force
The applied force is one of the most common types of force class 8. You can witness this force every day. The applied force is the force that we apply on objects using our hands or legs, or by any other object. When you push your chair, you are applying some force to move it in a specific direction.
Air Resistance Force
Air resistance force is the resistance that is naturally present in the air. When you throw an object up in the air, you will notice the object starting to de-accelerate, and this is due to air resistance and gravitational force.
Normal Force
The normal force is the force that is acting on a body that is at a state of rest. When an object rests on another object, it will experience a normal force, that is perpendicular to the surface. This happens to support the weight of the object when placed on a surface.
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Tension Force
When we talk about tension force, we refer to the pull force that a rope or string experiences when it is pulled by an object.
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Frictional Force
The frictional force is the force that acts on a moving object. A moving object will be in continuous contact with the surface. The surface exerts a force in the opposite direction of the moving object, which is called frictional force. Everyone experiences a frictional force when walking.
Non-Contact Forces
These forces happen when two objects are placed at some distance. The two objects never come in close contact with each other. The most common non-contact force is gravity. The object never comes in contact with it, yet it is always present and acting upon the object. Some of the essential con-contact forces are explained below.
Electromagnetic Force
The electromagnetic force comprises the magnetic and electric forces between atoms and molecules. The most common example of the electromagnetic force is a magnet. In a magnet, like poles repel and unlike poles attract towards each other.
Gravitational Force
When two objects have mass or matter, there exists gravitational force between them. Gravitational force can be considered an attractive force because it keeps pulling the object to it, for example, the gravity of the earth.
Nuclear Force
There is a strong bond between two or more nuclei or protons; this bond is called nuclear force. The nuclear force is also considered as an attractive force.
Electrostatic Force
Electrostatic force definition for class 8 can be stated as the force between two electrically charged particles. They can either be a repulsive or attractive force. Like charges will repel each other and unlike charges will attract each other.
Force is defined as the push or pull acting on an object. It means that when we push or pull a body, we apply force. Students of class 8 will study different types of forces that exist in nature. Different types of forces exist and students must know the different types of forces and their differences. In this part, we will discuss the different types of forces. The two main categories of force include contact and non-contact forces.
The most important differences between contact and non-contact forces are given here:
Difference Between Contact and Non-Contact Forces
Effects of a Force
When a force is applied on an object, it can produce different effects. The difference effects of a force produced on an object are given here:
When a force is applied on an object and an object is in motion, the force can stop the object from moving.
When a force is applied on an object and an object is at rest, the force can make the object move.
When a force is applied on an object it can slow down its motion
When a force is applied, the force can also increase the speed of an object
The applied force on an object can also change the direction of motion of an object
The force can also change the shape and size of an object
FAQs on Types of Force for Class 8
1. What is a force and what are its main effects according to the Class 8 syllabus?
A force is defined as a push or a pull on an object that can cause it to change its state of motion or shape. As per the CBSE Class 8 curriculum for 2025-26, the primary effects of a force are:
- Making a stationary object move.
- Stopping a moving object.
- Changing the speed of a moving object.
- Altering the direction of a moving object.
- Changing the shape or size of an object.
2. What are the two primary categories of forces studied in Class 8?
In Class 8 Physics, forces are broadly classified into two main categories based on whether the objects interacting are in physical contact:
- Contact Forces: These forces act only when two objects are in direct physical contact with each other. Examples include muscular force and frictional force.
- Non-Contact Forces: These forces can exert a push or pull on an object from a distance, without any direct touch. Examples include gravitational force, magnetic force, and electrostatic force.
3. Can you give some common examples of contact forces?
Contact forces are forces that result from the direct interaction between two objects. Common examples from daily life include:
- Muscular Force: The force exerted by the muscles of our body to perform actions like lifting, pushing, or pulling.
- Frictional Force: The force that opposes motion between two surfaces in contact. For example, the friction between a car's tires and the road.
- Tension Force: The pulling force transmitted through a string, rope, or cable when it is pulled taut by forces acting from opposite ends.
- Normal Force: The support force exerted by a surface upon an object that is in contact with it, acting perpendicular to the surface.
4. What are the key types of non-contact forces?
Non-contact forces act on objects without coming into physical contact with them. The key types are:
- Gravitational Force: The universal force of attraction between any two objects with mass. It's the force that pulls objects towards the centre of the Earth.
- Magnetic Force: The force of attraction or repulsion exerted by a magnet or a moving electric charge on other magnetic materials.
- Electrostatic Force: The force exerted by a charged body on another charged or uncharged body. Like charges repel, and unlike charges attract.
5. What is the fundamental difference between balanced and unbalanced forces?
The fundamental difference lies in their net effect on an object's motion. Balanced forces are equal in size and opposite in direction; they cancel each other out, resulting in a net force of zero and no change in the object's state of motion. In contrast, unbalanced forces are not equal and opposite, resulting in a net force that causes a change in the object's speed or direction of motion.
6. Why is friction often called a 'necessary evil'?
Friction is described as a 'necessary evil' because it is essential for many daily activities, yet it also has significant disadvantages.
- It is necessary because: Friction enables us to walk without slipping, write on paper, light a matchstick, and apply brakes to stop vehicles.
- It is considered an 'evil' because: It opposes motion, which means more energy is needed to move objects. It also causes wear and tear in machine parts and produces unwanted heat.
7. How can a non-contact force like gravity affect an object without ever touching it?
A non-contact force like gravity works through a concept known as a force field. An object with mass, such as the Earth, creates an invisible gravitational field in the space around it. Any other object that enters this field experiences the force of gravity. This field is what pulls a thrown ball back to the ground or keeps the Moon in orbit, acting across space without any physical contact.
