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ScienceClass 8FRICTION

FRICTION | Class 8 Science Notes

By ConceptScroll Team · Published on 17 July 2026 · 3 min read

FRICTION – this guide gives you a concise, exam-ready overview of FRICTION from Class 8 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.

Types of Friction

Friction can be classified into several types based on the nature of motion and the surfaces involved. The main types are static friction, sliding friction, rolling friction, and fluid friction. Static friction acts when an object is at rest and prevents it from moving despite an applied force. It adjusts its magnitude up to a maximum limit (limiting friction). Sliding friction occurs when one surface slides over another; it is usually less than static friction. Rolling friction acts when an object rolls over a surface, such as a ball or wheel; it is much smaller than sliding friction, which is why wheels are used to reduce friction. Fluid friction occurs when an object moves through a fluid (liquid or gas), such as air resistance or water resistance. Each type of friction plays a crucial role in daily life and technology. For example, rolling friction helps vehicles move efficiently, while fluid friction affects the speed of swimmers and airplanes.

📊 Diagram: Four separate illustrations showing (1) a block at rest with static friction, (2) a block sliding with sliding friction, (3) a rolling ball with rolling friction, and (4) an object moving through fluid with fluid friction.

🧪 Activity: No specific activity but examples help understand friction types.

🔗 Connection: Prepares for 'Advantages and Disadvantages of Friction' section discussing practical implications.

Frequently asked questions

1. Fill in the blanks. (a) Friction opposes the __________ between the surfaces in contact with each other. (b) Friction depends on the __________ of surfaces. (c) Friction produces __________. (d) Sprinkling of powder on the carrom board ______ friction. (e) Sliding friction is __________ than the static friction.

(a) motion (b) nature (c) heat (d) reduces (e) less

2. Four children were asked to arrange forces due to rolling, static and sliding frictions in a decreasing order. Their arrangements are given below. Choose the correct arrangement. (a) rolling, static, sliding (b) rolling, sliding, static (c) static, sliding, rolling (d) sliding, static, rolling

static, sliding, rolling

3. Alida 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 (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

wet marble floor, dry marble floor, newspaper and towel.

4. 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.

The frictional force acts upward along the surface of the desk, opposite to the direction of the sliding motion of the book (which is downward).

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