Mechanical Energy in Electrical Engineering in Kenya
It is the energy of motion – whether that energy is in action or stored. It exists in two forms;
Kinetic energy in Electrical Engineering in Kenya – this is energy possessed by a body by virtue of its motion and it represents the capacity of the body to do work by virtue of its speed. For Electrical Engineering in Kenya, if a force F acts on an object of mass m such that the mass accelerates uniformly from initial velocity v1 to a final velocity v2 over a distance s; then, work done over the distance s is
W = FS. But F = ma, and S = ut + ½at2. From the relation v = u + at, then;
t = (v-u)/a so that the work done is W = ma.s = ½m (v2 – u2) = ∆ke which is the work-energy relation theorem. In Electrical Engineering in Kenya, if a body starts from rest, then the work done on the object = kinetic energy gained by the object.
Potential Energy in Electrical Engineering in Kenya
It is the energy possessed by a body by virtue of its configuration (position) in a force field e.g. gravitational field; magnetic field etc. if an object of mass m is lifted to a height h from the ground, then;
Work done on the mass W = F.h = mgh i.e. work done on the object = gain in the potential energy by the object. Whether a body falls vertically or slides down an inclined plane, the work done on it by gravity depends only on its mass and on the difference in height between the initial and final positions. Potential energy in Electrical Engineering in Kenya of an object depends on its location and not by the route through which it arrived at that position. It follows that if a body is transported around a closed path, the change in potential energy vanishes i.e. potential energy in Electrical Engineering in Kenya is independent of the previous history because the gravitational force is conservative. A force is said to be conservative if the work done by the force from a point A to B depends only on the position vectors rA and rB. in particular, a conservative force must not depend on time, or on the velocity or acceleration of the body.
E.g. a 100kg crate of milk is pushed up a frictionless 30o inclined plane to a 1.5m high platform. How much work is done in the process?
Solution: the x-component of mg is –mgsin30o. This force in Electrical Engineering in Kenya must be balanced by the applied force F to prevent the crate from slipping down the plane. The work done by force F is;
W = Fdcosᶿ
Since F acts in the direction of motion, ᶿ=0 and cosᶿ = 1. The distance over which the force acts is the name of the incline namely
d = 1.5/ sin30, hence W = (mgsin30)d = 1470J.
Conclusion on Energy in Electrical Engineering in Kenya
Energy in Electrical Engineering in Kenya can be converted form one form to another, but can never be destroyed. The rate of this conversion is known as power in Electrical Engineering in Kenya. Mathematically, power = ∆W/ ∆t. the unit of power is watt (W), which is the rate of work (transfer of energy) of one joule per second. Power is also measured in horsepower (hp), where 1hp = 746W in Electrical Engineering in Kenya.