module 6

• Inertia

  The tendency of an object to resist change when in motion or when at rest
• Newton's first law of motion

  Also called the law of inertia
• If an object is moving

  Inertia will keep it in motion
• When an object is at rest

  It will continue to be at rest, unless there is a force applied on it
• What keeps an object at rest and what keeps it moving?

  1. Inertia

  2. Force applied
• What causes an object to change in motion?

  Unbalanced forces
• How does an object's mass affect its inertia?

  The greater the mass, the greater its inertia
• Sir Isaac Newton, a 17th century scientist, formulated laws explaining why objects are moving and why they do not move
• Newton's first law is also referred to as the law of inertia
• When riding on a bus and it suddenly stops

  Your body moves forward
• How does an object's mass affect its inertia?

  Greater mass has greater inertia, lesser mass has lesser inertia
• Objects move because it is their natural state
• Newton's Three Laws of Motion explain why objects are moving and why they do not move
• Inertia

  Resists change in motion
• When an object is at rest

  It will remain at rest
• When an object is moving

  Inertia will keep it moving
• Galileo

  • Developed the first concept of laws of motion
  • Developed the concept of motion in terms of velocity
  • Developed the idea of force that causes motion
  • Determined that the natural state of an object is rest or uniformed motion
  • Developed the idea that objects resist motion, inertia
• According to Galileo, objects in motion eventually stop because of a force called friction

  
• Galileo hypothesized that if friction could be entirely eliminated, the ball would reach exactly the same height or if the ball rolls horizontally and there's no friction that acts on it, the ball will never stop

  
• Isaac Newton

  • Expanded Galileo's work and came up with his Three Laws of Motion
  • Newton's first law of motion states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force

  
• Mass

  The amount of matter or substance that makes up an object, measured in kilograms
• Inertia of rest

  An object will stay in place unless something or somebody moves it
• Inertia of motion

  An object will continue at the same speed until a force acts on it
• Inertia of direction

  An object will stay moving in the same direction unless a force acts on it
• Force

  A push or a pull
• Newton (N)

  The unit of force, the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s
• Friction

  A force that opposes motion between any surfaces that are touching
• Friction occurs because no surface is perfectly smooth
• Rough surfaces have more friction than smooth surfaces
• Heavier objects have more friction because they are pressed harder with greater force than lighter objects
• Friction produces heat because it causes the molecules on rubbing surfaces to move faster and have more energy
• Balanced force

  A force in which the net force is equal to zero
• Unbalanced force

  A force in which the net force is greater than zero
• Unbalanced forces cause acceleration
• Only unbalanced force can change the motion and direction of an object