The mechanical energy.

In physics, the term work is always associated with movement at a building site we might see men and women carrying block's for one place to another the are doing work in the mechanical 

Seems the term work is said to be done whenever a force moved into the point of application in the direction of the force an engine which poll's a train among a track is doing work to overcome the force of friction. The work done depends on the force exerted by the engine it also depends on the total distance moved along the track by definition work is the product of the force and distance moved in the direction of force the unit of work is the joule <j>

Example of work include. The following stretching attraction in the spring compressing spring against the repulsive force between the molecules of the spring extending the surface tension force removing the molecules from a liquid during evaporation or boiling removing election from ab atom against the atomic force of attraction on the election.

Note that many activities which involves human fatigue do not necessarily limping that mechanical work is being performed. That's if a man Carrie's a heavily load on his head or with his hands. No work is being done if this is kept stationary guen when he walk, if the land is maintain at the same horizontal level no work is done by the men against the force of the weight of the load although work may been done against friction. If a man Carrie's the load up a ladder he is doing work against the weight if he decends the ladder carrying the load he does no work rather the force due to the weight of the load does work.

 

Mechanical energy can either be potential, kinetic or both.

Potential energy (p.e)

Potential energy is the  energy prossed by a body by virtual of h.o.s position or state of the stored up energy of a body in a particular position or state.

There are many form of potential energy of which are elastic potential energy (energy stored in a street or compressed elastic string or spring) and gravitational potential energy ( energy stored in a body by virtue of virtue it's position in relative to the center of earth).

Elastic p.e = ½ Fe 012

Elastic p.e= ½ fe² 

F= force applied 

E= extension produced

K= force contact or stiffness of elastic meterial or spring work done= force x distance in direction of force. 

Now gravitational potential energy is equal to the work done in moving an object from a reference point through a certain height to it's present position. The force that is being over come in moving the object through this height is the weight w on the object and the distance is the height in through which the object is moved.

Workdone = force x distance

Workdone= weight x height

Workdone= wxh but 

W               = km.

Workdone in a gravitational field

                  = Mgh

Since the workdone is equal to as gravitational potential energy then gravitational potential energy is = m g h.

Concept of kinetic energy 

Kinetic energy is the possessed by a body by virtue of it's motion. Wow workdone= fs.

F= force

S= distance in direction of force but from  newton's second law of motion f= ma 

Workdone=mas.

This is a work done in moving the body from rest or workdone in bringing it to rest at the case may be this workdone is equal to the kinetic energy k.e of the body k.e =mas 

Form equation of motion

V²= v²+2 as if the body everted form u=o then v²=2 as = v² race to power 2.

Put this in the expression for k.e then k.e = mu² race to power 2 k.e= ½ mu²

If the body is decelerated to rest then v² = u² -2 as and u= o1 

V² = 2as

As =ur  race to power 2

Put this in the expression for k.e 

K.e=½ mu²

K.e=½ mur.