Force of Friction
•• Friction is a contact force that opposes
relative motion between surfaces.
• • It acts in the direction opposite to motion.
3.
Causes of Friction
•• Caused by irregularities on surfaces in
contact.
• • Even smooth surfaces have microscopic
roughness.
• • These irregularities interlock, resisting
motion.
4.
Types of Friction
•• Static Friction – Prevents motion when at
rest.
• • Sliding Friction – Acts during motion.
• • Rolling Friction – When an object rolls.
• • Fluid Friction – Resistance in air or liquids.
5.
Friction – ANecessary Evil
• Advantages:
• • Helps in walking, writing, gripping, etc.
• Disadvantages:
• • Causes wear and tear.
• • Reduces machine efficiency.
6.
Ways of IncreasingFriction
• • Make surfaces rough (e.g., sand on icy
roads).
• • Use materials with more grip (e.g., rubber
soles).
• • Increase the contact force.
7.
Ways of ReducingFriction
• • Use lubricants (oil, grease).
• • Use ball bearings to convert sliding to rolling.
• • Use streamlined shapes.
8.
Fluid Friction
• •Occurs in liquids and gases.
• • Increases with speed and surface area.
• • Reduced by using streamlined shapes.
9.
Summary
• • Frictionopposes motion.
• • Caused by surface irregularities.
• • Has useful and harmful effects.
• • Can be increased or reduced as needed.
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