Forces

• Resultant force


  The single force that is equivalent to all the other forces acting on a given object
• Newton's first law for a stationary object


  If the resultant force on a stationary object is zero, the object will remain at rest
• Newton's first law for a moving object


  If the resultant force on a moving object is zero, the object will remain at constant velocity (same speed in same direction)
• Newton's Second Law


  Resultant force = Mass x Acceleration (F = ma)
• Newton's Second Law in words


  An object's acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass
• Weight


  The force that acts on an object due to gravity and the object's mass
• Quantities weight depends on

  • The object's mass
  • The gravitational field strength at the given position in the field
• Unit for weight


  Newton (N)
• Equipment to measure an object's weight


  • Calibrated spring-balance
  • Newton-meter