Force

• Force

  A push or pull acting upon an object due to the interaction with another object
• Force

  • Can change the size and shape of objects
  • Can make a stationary object move
  • Can speed up, slow down, or stop a moving object
  • Can change the direction of a moving object
• Real-life situations involving force

  • Pushing a cart
  • Kicking a soccer ball
  • Kicking an empty can (tumbang preso)
  • Modeling a lump of clay
• Types of force

  • Contact force
  • Non-contact force
  • Tension
  • Contact force
  • Gravitational force
  • Electric force
  • Magnetic force
  • Nuclear force
  • Static electricity force
• Contact force

  Force that is present when two or more surfaces or medium touch and interact
• Non-contact force

  Force that acts between objects that are not in direct physical contact
• Push

  Can cause movement away from the one pushing
• Pull

  Can cause movement towards the one pulling
• Force is commonly expressed in Newton (N)
• Balanced forces

  Forces acting on an object are equal and in opposite direction, cancelling each other out
• Unbalanced forces

  Forces do not cancel each other out
• Unbalanced forces

  Change the state of motion of an object (changing speed, direction, or both)
• Balanced forces on a stationary object

  Object stays at rest
• Balanced forces on a moving object

  Object continues to move at the same speed and direction
• Net force

  The sum of all forces acting on an object
• Balanced forces have a net force of zero
• Unbalanced forces have a non-zero net force
• Scalar

  Physical quantity that has magnitude only
• Vector

  Physical quantity that has both magnitude and direction
• Force

  A vector quantity
• Force

  • Magnitude: Represents the strength or intensity, typically measured in units such as newtons (N)
  • Direction: Indicates the line along which the force acts, described using angles or referencing specific axes or directions
• Force

  • If you push an object with a force of 10 newtons, the magnitude of that force is 10 N
• Whatever the factor acting on an object, they can be represented by vectors in a vector diagram
• A force can be represented using arrows, where the length of the arrow represents the magnitude or size of the force, and the arrowhead points to the direction of the force
• Cardinal directions

  • North: Upward
  • South: Downward
  • East: Right
  • West: Left
• Free body diagram

  A special type of force diagram that represents the forces acting on an object, with the force arrows labeled according to type, pointing in the direction of the force, and with a length proportional to the relative strength of the force
• Individual force types

  • Fgrav: Gravitational force
  • Ftens: Tension force from strings, ropes, wires, cables, etc.
  • Fspring: Force from compressed/stretched spring
  • Ffrict: Force from two surfaces sliding across each other
  • Fair: Force from object moving through surrounding air
  • Fnorm: Force resulting from two surfaces pressing against each other
  • Fapp: Force from a person pushing/pulling on an object
• Drawing free body diagrams

  1. Draw an arrow for each force, directed in the direction it acts

  2. Label the arrow to indicate its type

  3. Size the arrow to indicate its strength relative to any oppositely-directed force
• Free body diagrams

  • A rightward-moving car with locked wheels skidding to a stop: Fgrav (down), Fnorm (up), Ffrict (left)
  • A freight elevator attached by a cable being pulled upward and slowing down: Fgrav (down), Ftens (up)
  • A book at rest on a table: Fgrav (down), Fnorm (up)
  • A book attached to a string and hanging from the ceiling: Fgrav (down), Ftens (up)
• Motion has been studied for centuries by many great minds, including Aristotle, John Philoponus, Jean Buridan, Galileo Galilei, and Sir Isaac Newton
• Aristotle believed that a moving object needs a continuous application of force to keep it moving, and that the greater the force, the greater the speed
• John Philoponus conceptualized the idea of surrounding force similar to inertia found in Galileo's idea and Newton's First Law of Motion
• Jean Buridan further developed the "Theory of Impetus" introduced by Philoponus, where motion is possible through a "mover" that keeps the object moving with power proportional to the speed and mass of the object
• Galileo Galilei disagreed with Aristotle and claimed that even without a continuous application of force, an object can continue to move with constant speed in a straight line provided there are no outside forces acting on it
• Sir Isaac Newton used Galileo's ideas and eventually formulated the three laws of motion