Relationship Between Force and Motion

• Force


  A push or a pull that results from an interaction between objects
• Forces


  • Vector quantities (have both magnitude and direction)
  • Magnitude is the size or length of the vector
  • Direction is the line or course on which the vector is being directed
• Types of forces


  • Contact forces
  • Noncontact forces
• Contact forces


  Occur when objects are in direct contact with each other
• Contact forces


  • Hitting a shuttlecock with a badminton racket
  • Pushing a chair with your hand
  • Holding a pencil
• Noncontact forces


  Occur even when there is no direct contact between objects
• Noncontact forces


  • The push or pull of a magnet to a piece of iron
  • Earth's gravitational pull on the moon
• Types of external forces

  • Gravity
  • Normal force
  • Friction
• Gravity


  The force that attracts a body toward the center of Earth
• Normal force


  The force that counters gravity
• Friction


  The force that resists the motion of objects moving against each other
• Newton (N)


  The SI unit of force, the force needed to accelerate an object with a mass of 1 kilogram (kg) at 1 meter per second squared (m/s²)
• Dyne (dyn)


  The SI unit of force, the force needed to accelerate an object with a mass of 1 gram (g) at 1 centimeter per second squared (cm/s²)
• Net force


  Sum of all the forces acting on an object
• Motion


  The continuous change in the position of an object with respect to a reference point
• Motion


  • Described in terms of speed or velocity, displacement, acceleration, and time
• Balanced forces


  Forces that have the same magnitude but act in opposite directions, cancelling each other out
• Balanced forces allow objects at rest to remain at rest, or objects moving at a constant velocity to continue moving at that velocity