Mechanics Notes with PDF

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1. Simple Machines

• Purpose: To make work easier by allowing the same amount of work to be done with less force.
• Examples: Pulleys, levers, wheels, and screws.

2. Physical Quantities

• Scalar Quantities (Magnitude only)
  • Definition: Quantities that have only magnitude.
  • Examples: Volume, pressure, time, speed, distance, energy, and work.
• Vector Quantities (Magnitude and Direction)
  • Definition: Quantities that have both magnitude and direction.
  • Examples: Displacement, velocity, force, acceleration, and momentum.

3. Force, Mass, and Motion

• Newton’s Laws of Motion
  • First Law (Law of Inertia): An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.
    • Example (Inertia of Rest): When a train starts, a passenger leans backward because the lower body moves with the train, but the upper body tends to remain at rest.
  • Third Law (Action-Reaction): For every action, there is an equal and opposite reaction.
• Key Definitions
  • Force: The product of mass and acceleration (F = m × a).
  • Momentum: The product of mass and velocity. Therefore, Mass = Momentum / Velocity.
• Friction
  • It is more difficult to walk on ice than on a road because ice has less friction.
  • Static friction (needed to start moving an object) is greater than kinetic friction (needed to keep it moving). This is why pushing a loaded cart is harder to start than to keep moving.

4. Energy

• Law of Conservation of Energy: Energy can neither be created nor destroyed; it can only be transformed from one form to another.
• Types and Conversions
  • Wind Energy: A form of kinetic energy (energy of motion) converted into electrical energy by wind turbines.
  • Other Energy Conversions:
    • Heat → Electric: Solar cell
    • Electric → Sound: Loudspeaker
    • Mass → Heat: Nuclear reactor
    • Chemical → Heat and Light: Fuel combustion

5. Measurement and Properties

• Weight of Air: Air has weight. One liter of air weighs about 1.225 grams. Taking a deep breath (e.g., 4.8L) slightly increases a person’s weight.
• Cube Geometry: For a cube, if the volume (l³) equals the surface area (6l²), then the length of the edge (l) must be 6.
• Statics: The branch of mechanics that deals with objects in a state of rest or equilibrium.

Know More About Mechanics:

• Mechanics – Old Year Questions
• Mechanics One Liner Questions & Answers