Phys MYP5 U1 - FPEP

Introduction to Physics

  • Unit Title: Force, Pressure, Energy & Power

  • Key Concept: Relationship

  • Content Overview:

    • Forces: Types (Gravitational, Electric, Magnetic, Atomic, Nuclear)

    • Work and Energy

    • Pressure and Power

    • Gravity and Gravity Fields

    • Interrelations of Force, Energy, and Power

  • Global Context: Fairness and Development

Force

  • Definition: Push or pull of objects.

  • Causes: Interaction between objects.

    • Types of Force:

      • Applied Force

      • Friction Force

      • Normal Force

      • Gravitational Force

      • Magnetic Force

      • Electric Force

      • Spring Force

Effects of Force

  • Actions of Force:

    1. Can move an object at rest.

    2. Can bring an object to rest.

    3. Can increase or decrease speed.

    4. Changes shape or dimensions.

    5. Changes direction of motion.

  • Overall Effects:

    • Motion <-> Rest

    • Change in Direction

    • Change in Speed

Types of Force

  • Contact Forces:

    • Frictional Force

    • Applied Force

  • Non-Contact Forces:

    • Gravitational Force

    • Electrostatic Force

    • Magnetic Force

  • Net/Resultant Force:

    • Total force acting on an object taking direction into account.

    • Balanced Forces: No motion.

    • Unbalanced Forces: Motion occurs in the direction of the greater force.

Gravitational Force

  • Gravitation Concept: Attraction between bodies.

  • Historical Background:

    • Brahmagupta described gravity in 628 CE.

    • Galileo’s uniform acceleration theory.

    • Newton’s law of universal gravitation.

    • Cavendish confirmed Newton's laws.

Newton’s Universal Law of Gravitation

  • Statement: All masses attract each other.

  • Mathematical Relation:

    • F ∝ (m1 * m2) / r^2

  • Gravitational Constant (G):

    • SI unit: Newton (N)

Acceleration due to Gravity

  • Equation:

    • F = G * (M * m) / R^2

    • g = GM/R^2

  • Applications: Used to derive gravitational force on objects at the Earth’s surface.

Problem-Solving Examples

  1. Gravitational Force Between Elephants:

    • Masses: 1000 kg and 800 kg, distance = 5 m.

    • F = G * (m1 * m2) / r^2

  2. Gravitational Force Between Man and Bus:

    • Masses: 50 kg and 1500 kg, distance = 10 m.

    • Solve using the same formula.

Einstein’s Theory on Gravity

  • Concepts:

    • Time and space are curved by mass and energy.

    • Gravity acts as a distortion of spacetime rather than a force.

Black Holes

  • Definition: An astronomical object with a gravitational pull strong enough that not even light can escape it.

Centripetal and Centrifugal Force

  • Centripetal Force: Acts towards the center of rotation.

  • Centrifugal Force: Appears as acting away from the center in a rotating system.

  • Equations: F_c = mv^2/r

Types of Energy

  • Categories:

    • Kinetic: Energy of motion

    • Potential: Stored energy.

  • Work-Energy Principle:

    • Work done equals the change in kinetic energy.

Energy Sources

  • Types:

    • Renewable (Solar, Wind, Biomass)

    • Non-Renewable (Coal, Gas, Nuclear)

  • Environmental Impacts:

    • Greenhouse gas emissions, air, and water pollution, land degradation.

Conservation of Energy

  • Principle: Energy cannot be created or destroyed, only transformed from one form to another.

Efficiency

  • Definition: Ratio of useful output to total input.

  • Formula: η = (Output/Input) x 100%