NCERT Class 8 Science Chapter 5
Exploring Forces
NCERT Class 8 Science Chapter 5 introduces students to the concept of force — a push or pull that changes the state of motion or shape of an object. This CBSE chapter covers contact forces, non-contact forces, friction, gravity, and pressure, giving students the tools to understand why objects move, stop, or change direction. Real-world examples make the concepts easy to grasp.
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Key Terms
- Force
- A push or pull on an object that can change its speed, direction of motion, or shape; measured in newtons (N).
- Contact Force
- A force that acts between objects that are physically touching each other, such as friction, normal force, and muscular force.
- Non-contact Force
- A force that acts between objects without physical contact, such as gravitational force, magnetic force, and electrostatic force.
- Friction
- A contact force that opposes the relative motion between two surfaces in contact; it can be useful (walking, braking) or a hindrance (wear and tear).
- Gravity
- The non-contact attractive force exerted by the Earth (or any massive body) on all objects, pulling them towards its centre.
- Pressure
- The force applied per unit area; pressure increases when the same force is applied to a smaller area.
- Balanced Forces
- Two or more forces acting on an object that are equal in magnitude and opposite in direction, resulting in no change in the object's motion.
Frequently Asked Questions
What is force Class 8 Science?▾
A force is a push or pull that acts on an object. It can change the speed, direction, or shape of an object. Force is measured in newtons (N). NCERT Class 8 Chapter 5 classifies forces into contact forces (like friction) and non-contact forces (like gravity and magnetism).
What is the difference between contact and non-contact forces Class 8?▾
Contact forces require physical touching between objects — examples include friction, normal force, and applied force. Non-contact forces act between objects that are not physically touching — examples include gravity, magnetic force, and electrostatic force. NCERT Class 8 Chapter 5 covers both types.
What is friction Class 8 NCERT?▾
Friction is a force that opposes the motion of an object sliding over a surface. It acts at the point of contact between two surfaces. Friction is useful in everyday life (e.g., walking, writing, braking vehicles) but can also cause wear and tear. It can be reduced using lubricants or smooth surfaces.
What are balanced and unbalanced forces Class 8?▾
Balanced forces are equal and opposite forces that cancel each other out — the object remains at rest or moves at constant speed. Unbalanced forces are unequal, resulting in a net force that changes the object's motion (accelerates or decelerates it). Understanding this is key to NCERT Class 8 Science Chapter 5.
What is pressure Class 8 Science?▾
Pressure is defined as the force applied per unit area (Pressure = Force / Area). A given force creates more pressure when applied to a smaller area. This is why a sharp knife cuts better than a blunt one, and why snowshoes spread weight to prevent sinking.
What are the effects of force Class 8?▾
Force can: (1) Set a stationary object in motion, (2) Stop a moving object, (3) Change the speed of a moving object, (4) Change the direction of a moving object, (5) Change the shape of an object. All these effects are covered in NCERT Class 8 Science Chapter 5.
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