Physics🍎⚛️

• Force

  An effect that attempts to change the object's state from being static to motion or vice versa or attempts to change the direction of motion
• Fundamental forces in nature

  • Gravitational forces
  • Electromagnetic forces
  • Nuclear forces
  • Weak nuclear forces
  • Strong nuclear forces
• Object's weight


  The force of Earth's gravitational to the object
• The measuring unit of force and object's weight is newton (N)
• Relation to calculate the weight of an object

  Object's weight (W) = Object's mass (m) x Earth's gravitational acceleration (g)
• Electromagnet


  • Changes the electric energy into a magnetic energy
  • Used in making many devices such as electric winches and electric bells
• Electric generator (the dynamo)

  • Changes the mechanical (kinetic) energy into an electric energy
• Electric motor


  • Changes the electric energy into a mechanical energy
• Weak nuclear forces


  • Used to get radioactive elements and radiations, which are used in producing electricity, military purposes, scientific researches, industry, and medicine
• Strong nuclear forces


  • Used in industry
• Accompanied forces to motion

  • Forces originate due to motion
  • Forces cause motion
• Inertia


  A property of an object that has to resist the change of its state of rest or motion at a regular speed in a straight line unless an external force acted on it
• Friction forces


  • Resistant forces (against motion) originated between the object in motion and the medium touching it
• Benefits of friction


  • Prevents feet from slipping on roads during walking
  • Helps in stopping and starting cars motion
  • Helps in burning of match
• Harms of friction


  • Causes a great loss of mechanical energy
  • Produces heat energy due to the friction between some parts of the machines, which causes expansion of these parts and affects their performance
  • Causes the erosion of machines parts and damage them as well
• Examples of forces inside living systems

  • Heart muscle contraction and relaxation
  • Liquids are transported through pores and the walls of cells from the lower concentration to the higher one
  • Rising of water and salts from the soil to the plant
  • The contraction and relaxation of muscles
• Speed


  The distance covered by an object in a unit time
• Relative motion


  The change in an object's position or direction as the time passes relative to another object or a fixed point known as frame of reference
• Types of motion


  • Transitional motion
  • Periodic motion
  • Circular motion
  • Wave motion
• Mechanical waves


  • Produced by the vibration of the medium particles
  • Need a medium to transfer through
  • Their speed is relatively low
• Electromagnetic waves


  • Accompanied by electromagnetic forces
  • Spread in all media and free space
  • Their speed is extremely high equals 300 millions m/sec
• Force

  An effect that attempts to change the object's state from being static to motion or vice versa or attempts to change the direction of motion
• Object's weight

  The force of Earth's gravitational to the object
• Centre of gravity

  The effective point of the object's weight that is located at its centre
• Inertia

  A property of an object that has to resist the change of its state of rest or motion at a regular speed in a straight line unless an external force acted on it
• Friction forces

  Resistant forces (against motion) originated between the object in motion and the medium touching it
• Biological forces

  Forces inside living systems that enable living organisms to do their different biological operations
• Speed

  The distance covered by an object in a unit time
• Relative motion

  The change in an object's position or direction as time passes relative to another object or a fixed point known as frame of reference
• The reference point

  A fixed point used to determine the object's position or to describe its movement
• Transitional motion

  The motion in which the object's position is changed relative to a fixed point from time to time between initial and final positions
• Periodic motion

  A motion which is regularly repeated at equal periods of time
• Mechanical waves

  Waves that need a medium to transfer through
• Electromagnetic waves

  Waves accompanied by electromagnetic forces and they don't need a medium to travel through
• The pencil is still in a static state on the desk because there is no force acting on it
• The static ball moves when you kick it because the object changes its state when a proper force acts on it
• When you push a wall, it doesn't move because the force acting on it is improper
• The mass of the object remains constant by changing its position on the Earth's surface because the mass of the object is the amount of matter that the object contains, and it doesn't change by changing the position
• The phrase "The weight of a bag of sugar equals 1 kg" is scientifically not accurate because the amount of 1 kg represents the mass of a bag of sugar and not its weight
• The weight of the object is always greater than its mass because the weight equals multiplying the mass of the object by Earth's gravitational acceleration