Energy

• Force


  A push or pull upon an object resulting from its interaction with another object. Forces can cause an object to accelerate, decelerate, remain in place, or change direction.
• Types of Forces


  • Contact Forces
  • Non-contact Forces
• Contact Forces


  • Forces that occur when objects are physically touching. Examples include: Frictional Force, Tension Force, Normal Force, Air Resistance Force, Applied Force
• Non-contact Forces


  • Forces that act over a distance without physical contact. Examples include: Gravitational Force, Magnetic Force, Electrical Force
• Newton's Laws of Motion

  • First Law (Law of Inertia)
  • Second Law
  • Third Law
• 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
• Second Law


  The acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. F=ma
• Third Law


  For every action, there is an equal and opposite reaction
• Newton


  The SI unit of force, the force required to accelerate
• Energy


  The capacity to do work or produce change. It can exist in various forms and can be transformed from one form to another.
• Types of Energy


  • Kinetic Energy (KE)
  • Potential Energy (PE)
• Kinetic Energy (KE)


  The energy of motion. KE= 1/2mv^2
• Gravitational Potential Energy


  Energy stored in an object as it is held above the ground. PE=mgh
• Elastic Potential Energy


  Energy stored in elastic materials as the result of their stretching or compressing
• Energy cannot be created or destroyed; it can only be transformed from one form to another. The total energy of an isolated system remains constant.
• Work


  Work is done when a force causes displacement of an object. W=Fdcosθ
• Power

  The rate at which work is done or energy is transferred. P=

  t

  W

  ​
• Joule


  The SI unit of energy,
• When a force is applied to an object


  It can transfer energy to that object
• Calculating Force


  • If a 10 kg object is accelerating at 2 m/s², the force applied is: F=ma=10×2=20 N
• Calculating Work


  • If a force of 15 N is applied to move an object 3 meters, the work done is: W=Fdcosθ=15×3×cos0

  ∘

  =45 J
• Calculating kinetic energy


  A 5 kg object moving at 3 m/s has a kinetic energy of$Ke=$$1/2mv^2 =$$1/2 *$$5 *$$3^2 =$$22.5J$