PhysicsVector QuantityNCTB পদার্থবিজ্ঞান অধ্যায় ৩ (বল)
Friction
Bengali: ঘর্ষণ•Pronunciation: ফ্রিকশন•Symbol: f \text{ বা } f_s, f_k
Standard Definition:
A resistive force that opposes the relative motion or tendency of motion between two touching surfaces.
📐 Mathematical Equation, Units & Dimensions
Defining Mathematical Equation
Standard SI Unit
N (Newton)($N$ (নিউটন))
Dimensional Analysis
CGS Unit
dyn
📖 Physical Concept & Comprehensive Explanation
Friction arises due to microscopic asperities interlocking across contact surfaces. It is categorized into static, kinetic, rolling, and fluid friction. While friction wastes mechanical energy as heat, it is indispensable for walking, braking vehicles, and grasping objects, making it a 'necessary evil'.
🎯 High-Yield Revision Points
- ✓4 types of friction: static, kinetic, rolling, and fluid friction.
- ✓Proportional to the normal contact force (f = mu * R).
- ✓Referred to as a 'necessary evil' in applied mechanics.
Use Online Solver for Friction
Compute step-by-step solutions, verify formulas, and plot interactive diagrams on biggan.me.
❓ Frequently Asked Exam Questions (FAQ)
Common questions in board and competitive entrance examinations
Q1: Why is friction called a necessary evil?
It dissipates mechanical energy and wears down machine parts (an evil), yet it is indispensable for walking, gripping, and vehicle braking (necessary).