FORCES AND THEIR EFFECTS

FORCES AND THEIR EFFECTS

1. Definition

   • 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

2. Representation

   • Vectors
     • Vectors are usually drawn as arrows.

3. Types

   • Contact and Non-Contact forces Instantaneous and Constant forces

4. WEIGHT

   • The weight of an object is the force of attraction that gravity exerts on it. Depends on: mass and gravity w = m x g
   • WEIGHT AND MASS
     • 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.
   • Units
     • SI: Newton 9.8 newtons = 1 kilopond
   • WEIGHT AND DENSITY
     • d = m/v w = V x d x g

5. UPTHRUST

   • Depends on: - Volume - Density upthrust = V x d x g
   • ARCHYMEDES' PRINCIPLE Law of buoyancy
     • 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.
     • Applications
       • Boats and submarine

6. FORCES & MOTION

   • NEWTON'S LAWS
     • First Law
       • An object in motion on which no forces act has uniform rectilinear motion.
     • Second Law
       • 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.
     • Third Law
       • 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.
   • FORCES & EQUILIBRIUM
     • An object is in equilibrium when the resultant of all the forces that act on it is nil.
   • FORCE & WORK
     • 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
     • Unit of work
       • 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.

7. ENERGY & WORK

   • MECHANICAL ENERGY
     • 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.
     • KINETIC ENERGY
       • 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)
     • POTENTIAL ENERGY
       • An object stores potential energy when it moves in the opposite direction to a force acting on it.
       • Elastic potential Energy
       • Gratitational Potential Energy

8. SIMPLE MACHINES

   • The Lever
     • Types of levers
   • Static or fixed pulley