FORCES AND THEIR EFFECTS

Nota:

• A vector quantity that tends to produce an acceleration of a body in the direction of its application or a change of the direction that  the object is moving or a deformation of a body

1. Vectors

   Nota:

   • Vectors are usually drawn as arrows.

Nota:

• Contact and Non-Contact forces Instantaneous and Constant forces

Nota:

• The weight of an object is the force of attraction that gravity exerts on it. Depends on: mass and gravity w = m x g

1. WEIGHT AND MASS

   Nota:

   • MASS is an invariable quantity that depends on the amount of matter. Mass is measured with a balance. WEIGHT depends on gravity. So, it changes with it. Weight is measured with a dynamometer.
2. Units

   Nota:

   • SI: Newton 9.8 newtons = 1 kilopond
3. WEIGHT AND DENSITY

   Nota:

   • d = m/v w = V x d x g

Nota:

• Depends on: - Volume - Density upthrust = V x d x g

1. ARCHYMEDES' PRINCIPLE Law of buoyancy

   Nota:

   • Archimedes' principle indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.
   1. Applications

      Nota:

      • Boats and submarine

1. NEWTON'S LAWS
   1. First Law

      Nota:

      • An object in motion on which no forces act has uniform rectilinear motion.
   2. Second Law

      Nota:

      • A constant force exerted on an object gives it a constan acceleration that is directly proportional to the force and inversely proportional to the object's mass.
   3. Third Law

      Nota:

      • When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
2. FORCES & EQUILIBRIUM

   Nota:

   • An object is in equilibrium when the resultant of all the forces that act on it is nil.
3. FORCE & WORK

   Nota:

   • Work is done when an object is displaced because a force acts on it, either partialy or completely in the same direction as the motion. W = F x d
   1. Unit of work

      Nota:

      • Joule:  is the work done by an object that, subjected to a force of 1 N, is displaced 1 m in the same direction as the force.

1. MECHANICAL ENERGY

   Nota:

   • Objects have mechanical energy when they move at a certain speed or are displaced with respect to their position of equilibrium, or are at a certain height above the ground.
   1. KINETIC ENERGY

      Nota:

      • EK is the energy that an object in motion has. it is depend on the mass of the object and how fast it moves (its speed)
   2. POTENTIAL ENERGY

      Nota:

      • An object stores potential energy when it moves in the opposite direction to a force acting on it.
      1. Elastic potential Energy
      2. Gratitational Potential Energy

1. The Lever
   1. Types of levers
2. Static or fixed pulley