Grade VIII Science

Force and Pressure

• Force – A Push or a Pull
  Introduction to force as a push or pull on an object. Covers how forces arise from interactions and basic examples from daily life, such as pushing a door or pulling a rope.
• Forces are due to an Interaction
  Explanation that a force requires at least two objects interacting with each other. Discusses scenarios where isolated objects cannot experience force without interaction, emphasizing mutual forces.
• Exploring Forces
  Hands-on exploration of forces, including activities to demonstrate balanced and unbalanced forces. Includes concepts like net force and how multiple forces can act in the same or opposite directions.
• A Force can Change the State of Motion
  How force affects an object's motion: starting, stopping, or changing speed/direction. Sub-points include:
  
  • State of Motion: Defining motion in terms of velocity (speed and direction) and inertia (resistance to change in motion).
• Force can Change the Shape of an Object
  Effects of force beyond motion, such as deforming or compressing objects (e.g., squeezing a rubber ball or stretching a spring).
• Contact Forces
  Forces that act when objects are in physical contact. Sub-types include:
  
  • Muscular Force: Force exerted by muscles in humans and animals (e.g., lifting weights).
  • Friction: Opposing force between surfaces in contact, including its role in walking, writing, and reducing motion.
• Non-contact Forces
  Forces that act at a distance without physical touch. Sub-types include:
  
  • Magnetic Force: Attraction or repulsion between magnets or magnetic materials.
  • Electrostatic Force: Attraction or repulsion between charged objects (e.g., rubbed balloon sticking to a wall).
  • Gravitational Force: Universal attraction between masses, including Earth's gravity pulling objects downward.
• Pressure
  Introduction to pressure as force applied per unit area (formula: Pressure = Force / Area). Explains why the same force exerts more pressure on a smaller area (e.g., sharp vs. blunt objects).
• Pressure Exerted by Liquids and Gases
  How fluids (liquids and gases) exert pressure in all directions. Covers concepts like buoyant force (upthrust) in liquids and how pressure increases with depth in fluids.
• Atmospheric Pressure
  Pressure due to the weight of air in the atmosphere. Includes demonstrations (e.g., why we don't feel it, effects on objects like syringes or fountains) and real-life applications (e.g., drinking through a straw).