Concept Builder: Types of Forces and Pressure in Daily Life- class 8

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Concept Builder: Types of Forces and Pressure in Daily Life

Concept Builder Notes: Types of Forces and Pressure in Daily Life

🔹 Types of Forces

Forces can be categorized based on their interaction as:
  • Contact Forces: These act when objects are physically touching.
    • Frictional Force: Opposes motion between surfaces.
    • Muscular Force: Applied by human or animal muscles.
    • Tension Force: Force through strings or ropes.
    • Normal Force: Perpendicular force from a surface.
  • Non-Contact Forces: These act from a distance without physical contact.
    • Gravitational Force: Pulls objects toward the Earth.
    • Magnetic Force: Between magnetic materials or magnets.
    • Electrostatic Force: Between charged objects.
Example: A falling apple experiences gravitational force. A rubbed balloon attracts bits of paper due to electrostatic force.

🔹 What is Pressure?

Pressure is defined as the force applied per unit area.
Pressure = Force / Area (Unit: pascal or Pa)

🔹 Pressure in Daily Life

  • Knives: Have sharp edges to concentrate force on a smaller area, increasing pressure for easier cutting.
  • Nails: Pointed tips reduce area, increasing pressure to drive them into walls.
  • Elephants vs Camels: Camels have broad feet to reduce pressure on sand and prevent sinking.
  • School Bags: Wider straps distribute force, reducing pressure on shoulders.

🔹 Liquid Pressure

Pressure in liquids increases with depth and acts in all directions.
Example: Dams are built thicker at the bottom because water pressure increases with depth.

🔹 Gaseous Pressure

  • Gases exert pressure on the walls of their containers.
  • Used in inflating tires, spray cans, pressure cookers.
💡 Tip: Pressure is crucial in medical syringes, hydraulic lifts, and even breathing!

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