WORK (J)

WORK (J)

1. it is the product of the force applied and the displacement in the direction of the force

   • W=work in joules(J) F=force in newtons(N) x=displacement in metres(m)
     • W F x
     • DISTANCE:ACTUAL PATH LENGTH TAKEN DISPLACEMENT:STRAIGHT LINE MOVEMENT
     • FOR WORK TO BE DONE :1.a force must act on an object 2.the object must be displaced in the direction of the force
       • EXAMPLES
         • 1.An object is moved against frictional forces 2.An object is lifted against the weight 3.A spring is pulled or compressed 4. An object is accerealted against its inertia
     • NO WORK IS DONE :1.either the force or displacement is zero 2. the motion of the object is perpendicular to the applied force

2. POWER (W)

   • the rate at which work is done
     • W=work in joules(J) P= power in watts(W) t =time in seconds (S)
       • W P T
   • ENERGY
     • LIGHT ENERGY
       • HEAT ENERGY
         • KETTLES ,TOASTERS,STOVES
       • MAIN SOURCE :SUN
         • ORIGIN:HEAT ENERGY,CHEMICAL ENERGY AND ELECTRICAL ENERGY
           • HEAT ENERGY ->LIGHT ENERGY
     • ELECTRICAL ENERGY
       • BATTERIES AND DYNAMOS
         • CHEMICAL ENERGY->ELECTRICAL ENERGY
         • KINETIC ENERGY ->ELECTRICAL ENERGY
     • CHEMICAL POTENTIAL ENERGY
       • react and energy can be released ,sudden release of energy can be an explosion
         • CHEMICAL POTENTIAL ENERGY->HEAT ,LIGHT AND SOUND ENERGY
     • ELASTIC POTENTIAL ENERGY
       • RETURN TO ITS NATURAL OR UNSTRETCHED POSITION ,ELECTRIC ENERGY IS CONVERTED TO WORK
         • ELASTIC POTENTIAL ENERGY->KINETIC ENERGY
     • NUCLEAR POWER
       • Nuclear reaction occurs, energy in the form of heat and light are given out .Produce steam which turns turbines in dynamos at PS
       • DYNAMOS PRODUCE ELCTRUCAL ENERGY WHICH IN TURN PRODUCES HEAT AND LIGHT (ENERGY TRANSFORMATIONS)
     • KINETIC ENERGY
       • THIS IS THE ENERGY WHICH A BODY POSESSES DUE ITS MOTION
         • THE GREATER THE SPEED OF THE BODY THE GREATER WILL BE THE BODIES KINETIC ENERGY
     • GRAVIATIONAL POTENTIAL ENERGY (Ep)
       • THE ENERGY WHICH A BODY POSSESSES DUE TO ITS POSITION ABOVE THE GROUND
         • GRAVITATIONAL POTENTIAL ENERGY ->KINETIC ENERGY

3. ENERGY TRANSFORMATION

   • Coal (chemical potential energy)1.Boil water to produce steam (chemical potential to heat ) 2. steam used to turn turbines in dynamos (kinetic to electric energy )
     • electrical energy->light and heat energy
   • MECHANICAL ENERGY
     • the sum of kinetic(Ek) and gravitational potential energy(Ep)
       • can be converted,transferred and be conserved
       • is conserved if friction is ignored