work energy and power ss1 physics

  1. Udimi
    work energy and power ss1  physics

    work is defined as a force causing the movement or displacement of an object.

    Work done is defined as the product of force and the displacement in the direction of force.

    work = F × S

    WORK= FORCE(NEWTON) ×DISPLACEMENT(METRES)

    The magnitude of work done is given by

    Work Done= force×distance

    W=mg×h                            (f=mg)

    W=mgh

    The unit of work is  joules.

    EXAMPLE

    A girl of mass 80kg  runs up a set  steps of total height

    7.0m . Find the work done against gravity.

    solution

    work done = mgh

    =80×10×7    (g=10m/s¯²)

    =5600 Joules

    Energy

    Energy is the capacity to do work. It is measure in joules.

    FORMS OF ENERGY

    1. Mechanical energy
    2.  Heat energy
    3. Light energy
    4. Chemical energy
    5. Electrical energy
    6. Atomic energy
    7. Solar energy

    TYPES OF MECHANICAL ENERGY

    Mechanical energy  is categorize into two types, which are:

    1. Potential energy
    2. Kinetic energy

    Potential energy is the energy possessed by a body due to its position or state.

    A body may posses a potential energy due to its position  in a force field .  If the force field is the gravitational field,the body is said to have gravitational potential energy.

    Egp=mgh

    where g is acceleration due to gravity,

    m is mass and h is height above the ground.

    Egp  is gravitational potential energy.

    Examples of Potential energy are:

    1. An electric charge at rest in an electric field.
    2. A magnet at rest in magnetic field.
    3. When petrol,wood, or kero is burn.

    Kinetic energy

    Kinetic energy (K.E) is the energy possessed by a body due to its motion.

    Example of kinetic energy are :

    1. A boy running a race.
    2.  Air or wind in motion.
    3.  Electrical charges in motion.
    4.  A  body or an object falling under gravity.

    The kinetic energy(K.E) of  a body in motion is giving by

    K.E=½mv²

    Where m is the mass and v is the velocity.

    PROBLEM ON KINETIC ENERGY

    An object of mass 8kg is moving  at velocity of 20ms¯²

    solution

    K.E=½mv²

    K.E= ½ ×8×20²

    K.E=4×400

    K.E=1600 Joules

    POWER

    Power is defined as the rate at which work is done.

    power =power⁄time

     

     

     

     

     

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