CG SCERT (Chhattisgarh Board) Class 8 Science & Technology Solutions | 2026-27 Official Edition
Welcome to the complete, 100% textbook-grounded CG Board Class 8 Science Chapter 14 Solutions: Friction (घर्षण) in Bilingual Format (English Medium + हिंदी माध्यम). Every in-text question (Answer these / इनके उत्तर दीजिए) and end-of-chapter exercise (Exercises / अभ्यास के प्रश्न) has been solved strictly from the official 2026-27 SCERT Chhattisgarh Raipur textbook.
- English: Why do we slip down on stepping over a banana peel?
- Answer:
- English: A banana peel has a smooth and slippery inner surface. When we step on a banana peel, it acts as a lubricant between the sole of our shoes/feet and the ground. This greatly reduces the force of friction required for walking. Due to insufficient friction, our feet cannot get a proper grip on the floor, causing us to slip down.
- English: Explain why sportsmen wear shoes with spikes?
- Answer:
- English: Sportsmen wear shoes with spikes (grooves or pointed projections) to increase the force of friction between the soles of their shoes and the ground. The spikes dig into the ground/track, providing a firmer grip and preventing athletes from slipping while running fast or making sharp turns.
- English: Abdul has to push a lighter box and Rama has to push a heavier box on the same surface. Who will experience more frictional force and why?
- Answer:
- English: Rama will experience more frictional force. The force of friction depends on how hard the two surfaces are pressed together. A heavier box exerts a greater downward force (weight) on the floor, pressing the surface irregularities of the box and floor more firmly into each other. As a result, the interlocking of irregularities is stronger, requiring a larger force to overcome friction.
- English: Explain contact and non-contact force with examples.
- Answer:
- English:
- Contact Force: A force that can be exerted only when two objects are in physical contact with each other is called a contact force.
- Examples: Muscular force (pushing a box) and Frictional force (force acting between a rolling ball and the table).
- Non-contact Force: A force that can act between two objects without being in physical contact with each other is called a non-contact force.
- Examples: Magnetic force (magnet attracting iron pieces), Electrostatic force (charged body attracting uncharged objects), and Gravitational force (earth pulling objects downwards).
- Hindi:
- English: Explain how the shape of an aeroplane reduces friction.
- Answer:
- English: When an aeroplane moves through air, it experiences fluid friction (drag). To minimize air resistance, aeroplanes are given a special streamlined shape (narrow at the front and back, and broader in the middle, resembling birds). This streamlined body allows air to flow smoothly around it with minimal resistance, preventing energy loss due to friction.
- English: By continuous movement, why does a machine get heated up?
- Answer:
- English: A machine gets heated up during continuous movement because friction generates heat. When moving parts of a machine rub against each other, mechanical energy is converted into heat energy due to resistance between interlocking surface irregularities.
- English: Can friction be less or become nil by using lubricants?
- Answer:
- English: Friction can be significantly reduced by using lubricants (such as oil, grease, or graphite), but it can never become zero (nil). This is because no physical surface is perfectly smooth; microscopic irregularities always exist on all surfaces.
- (a) Friction opposes the ……………….. between the surfaces in contact with each other.
- Answer:relative motion
- (b) Friction depends on the ……………….. of surfaces.
- Answer:nature (or smoothness/roughness)
- (c) Friction produces …………………
- Answer:heat
- (d) Sprinkling of powder on the carrom board ……………….. friction.
- Answer:reduces
- (e) Sliding friction is ……………….. than the static friction.
- Answer:smaller (or less)
Q1
Aabida runs her toy car on dry marble…
Answer a गीला संगमरमर का फर्श सूखा संगमरमर…
📝 Question:
Aabida runs her toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces, in increasing order will be: Options: (a) Wet marble floor, dry marble floor, newspaper and towel. (b) Newspaper, towel, dry marble floor, wet marble floor. (c) Towel, newspaper, dry marble floor, wet marble floor. * (d) Wet marble floor, dry marble floor, towel, newspaper
💡 Solution:
(a) Wet marble floor, dry marble floor, newspaper and towel.**
- Reason & Explanation:
- English: Friction increases with increase in surface roughness. Wet marble floor is smoothest (least friction) < Dry marble floor < Newspaper < Towel (roughest surface, maximum friction).
question
Answer the following questions
मान लीजिए आपकी लिखने की मेज थोड़ा झुकी…
📝 Question:
Answer the following questions:**
💡 Solution:
Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.
- Direction of Frictional Force: The force of friction always acts in the direction opposite to the direction of motion of the object. Since the book is sliding downwards along the tilted surface of the desk, the frictional force acts upwards along the inclined desk surface.
- Diagram Explanation:
- Draw an inclined straight line representing the tilted desk surface.
- Place a rectangular box on the line representing the sliding book.
- Draw a downward arrow along the inclined surface labeled “Direction of Motion / Sliding”.
- Draw an upward arrow parallel to the inclined surface labeled “Direction of Frictional Force”.
- English: Would it be easier or more difficult for you to walk on the floor of soapy water? Give reason in support of your answer.
- Answer:
- English: It would be much more difficult to walk on a floor covered with soapy water.
- Reason: Soapy water acts as a lubricant that fills up the microscopic irregularities between the floor and the soles of our feet/shoes. This reduces the force of friction drastically. Since walking requires sufficient friction to push backwards against the ground without slipping, the lack of friction on a soapy floor makes walking very difficult and increases the risk of slipping.
| Friction as a Friend (Benefits) | Friction as a Foe (Disadvantages) |
|---|---|
| 1. Enables us to walk on the floor without slipping. | 1. Causes wear and tear of shoe soles, tyres, and machine screws. |
| 2. Allows us to write with pen/pencil on paper or chalk on blackboard. | 2. Produces heat in machines, causing wastage of valuable energy. |
| 3. Helps vehicles to stop or slow down when brakes are applied. | 3. Opposes motion and reduces machine efficiency. |
| 4. Enables nails and screws to hold firmly in walls. | 4. Causes forest fires due to friction between rubbing dry branches. |
| — | — |
- English: Give example to show that friction is both a friend and a foe.
- Answer:
- English: Friction is known as a “necessary evil” because it plays both a positive role (friend) and a negative role (foe) in daily life.
- Comparison Table:
- English: Explain why the objects moving in fluids must have special shapes.
- Answer:
- English: Fluids (liquids and gases) exert a resistive force called fluid friction or drag on objects moving through them. Overcoming drag requires objects to expend a large amount of energy. Therefore, objects like aeroplanes, ships, boats, and rockets are given special streamlined shapes (curved and pointed ends). This shape allows fluids to flow smoothly past the object with minimum resistance, reducing energy loss.
- English: Suppose you are outside your home and an earthquake strikes. What precautions would you take to protect yourself?
- Answer:
- English: If I am outside my home during an earthquake, I will take the following precautions:
- Move to a clear, open spot away from buildings, high structures, trees, and overhead electric power lines.
- Drop to the ground and sit down to avoid losing balance.
- If travelling in a car or a bus, do not come out; ask the driver to drive slowly to a clear open spot away from bridges.
- Stay at the safe open spot until the shaking and tremors completely stop.
Q3
Try To Do This Also
अपने मातापिता से भूकंप द्वारा जनधन की हुई…
📝 Question:
Try To Do This Also:**
💡 Solution:
Ask your parents about the huge damage to life and property caused by these earthquakes; collect a few pictures showing the damage caused by the earthquakes from newspapers and magazines. Prepare a short report on the suffering of the people during and after the earthquakes.
- Project Report on Earthquake Damage & Human Suffering:
- Cause & Nature: Earthquakes are sudden trembling of the Earth’s crust caused by movements of tectonic plates. Major earthquakes cause severe destruction.
- Damage to Life & Property: Destruction of buildings, bridges, and dams traps people under heavy debris, leading to fatalities and injuries. Communication and electric power networks get disconnected.
- Human Suffering: Victims face severe shortages of safe drinking water, food, clothes, and medical care. Displaced families live in temporary relief camps, dealing with emotional trauma and health epidemics.