science

• Projectile


  Any object thrown horizontally or vertically upon which the only force acting is gravity
• Projectile motion


  • Projectiles travel with a parabolic trajectory due to the influence of gravity
  • No horizontal forces act upon projectiles; thus, there is no horizontal acceleration
  • The horizontal motion of a projectile is independent of its vertical motion

  
• Range


  The horizontal displacement of the projectile from its initial position to a point in which its vertical displacement is zero
• Uniform motion


  The motion of an object that moves with a constant velocity (i.e., constant speed and direction)
• Uniformly accelerated motion


  The motion of an object that moves with a constant acceleration
• Projectile motion


  The motion of an object thrown or projected into the air, subject to only the acceleration of gravity
• Trajectory


  The path followed by a projectile
• Height


  The vertical displacement of a projectile
• Horizontal component (x-component)


  Determines how fast the football moves forward
• Vertical component (y-component)


  Determines how fast the football moves upward and, later, downward
• Once the projectile is airborne, gravity is the only force acting on it, neglecting air resistance. Since gravity always acts downward, it affects only the vertical component of the velocity
• On its upward flight, the vertical component of the velocity (Vᵧ) decreases in value until it becomes zero at the maximum height
• At its peak, the projectile stops the value until it matches the original magnitude at the start
• The horizontal component (Vₓ) is unaffected by gravity. Its value remains constant throughout
• The time (t) going up equals the time going down, provided the projectile takes off and lands at the same level
• The only force acting on a projectile is the force of gravity; it is a free-falling object
• The acceleration due to gravity is directed downwards and has a value of -9.8 m/s²
• Calculating horizontal and vertical components of initial velocity


  1. Vᵢₓ = Vᵢcosθ

  2. Vᵢᵧ = Vᵢsinθ
• Momentum


  The difficulty encountered in bringing the object to rest. It is also defined as the "mass in motion or inertia in motion."
• Momentum (p)


  • A property of a moving body that the body has by its mass and motion
  • It can be defined as "mass in motion"
  • It is the product of mass and velocity
  • In equation for: p = (m)(v) where m = mass (kg), v = velocity (m/s), p = momentum (kgm/s)
• Impulse


  • The change in momentum
  • The product of force multiplied by time
  • In equation form: I = (F)(t) where I = Impulse (change in p, Ns), F = Force (Newton, N), t = time (second, s)
• Law of Conservation of Momentum

  • The total momentum before the collision is equal to the total momentum after the collision
  • In equation: pᵢ = pf or m1v1 + m2v2 = m1v1' = m2v2'
• Types of collision


  • Elastic collision
  • Inelastic collision
• Elastic collision


  One in which the total kinetic energy of the system does not change, and colliding objects bounce after the collision
• Inelastic collision


  • One in which the total kinetic energy of the system changes (i.e., converted to some form of energy)
  • Objects that stick together after the collision are said to be perfectly inelastic
  • Some or maximum KE is lost; thus, kinetic energy is not conserved
• Mechanical energy


  The energy of either an object in motion or the energy stored in objects by their position
• Kinetic energy


  • The energy in motion
  • It is affected by the mass and the velocity of an object
  • The higher the mass and the velocity, the higher the kinetic energy
  • In equation form, KE = ½ mv2 where KE = Kinetic Energy (joules, J), m = mass (kg), v = velocity (m/s)
• Potential energy


  • The energy in position
  • It is affected by the mass, acceleration due to gravity, and the object's height
  • The higher the mass and the height, the higher the potential energy
  • In equation form, PE = mgh where PE = Potential Energy (joules, J), m = mass (kg), g = acceleration due to gravity (9.8m/s2), h = height (meter, m)
• Law of Conservation of Mechanical Energy

  • The total mechanical energy in a closed system remains constant
  • Energy cannot be created nor destroyed. It can only be formed from one form into another
  • In equation, ½ mv2₍ᵢ₎+ mgh₍ᵢ₎ = ½ mv2₍f₎+ mgh₍f₎
• Thermodynamics


  • A branch of Physics that looks at how changes in energy, work, and the flow of heat influence each other
  • It can explain the workings of an internal combustion engine, a refrigerator, and the sun
  • Thermodynamics is mainly concerned with the transformation of heat into mechanical energy
  • It plays an important part in technology, in as much as the majority of raw energy available for our consumption is liberated in the form of heat

  
• First Law of Thermodynamics

  • Whenever heat is added to a system, an equal amount of some other form of energy appears
  • Work can be converted into heat in the same manner that heat can be converted into work
  • ΔU = Q - W where: ΔU = the change in the system's internal energy, W = the net work done by the system, Q = the net amount of heat flowing into a system during a given process

  
• Heat transfer


  • The heat movement of thermal energy from one object to another of different temperatures
  • Lower to higher temperature (non-spontaneous)
  • Higher to lower temperature (spontaneous)

  
• Second Law of Thermodynamics

  • Heat will never flow from a cold temperature to a hot temperature object
  • Entropy is a scientific concept commonly associated with disorder, randomness, or uncertainty

  
• Heat pump


  An instrument used to reverse the natural flow of heat or spontaneous heat transfer into a non-spontaneous process by absorbing heat from a cold space and releasing it to a warmer one

  
• Heat engine


  A device that changes thermal energy into mechanical work

  
• Cycle stroke


  1. Intake: Moves down, Filled in the cylinder

  2. Compression: Moves up, Compressed into the fractional amount

  3. Power: Moved down, Ignite by the spark plug

  4. Exhaust: Moves up, Expelled out by the exhaust pipe
• Thermal efficiency


  • The fraction of heat that becomes useful work
  • It measures how much of the input energy ends up doing useful work
  • Efficiency = Work done/ Input heat = W/ QH
  • Qc = energy removed by heat/energy in cold reservoir
  • Qh = energy added by heating/energy in a hot reservoir