Engineering in Kenya

# Mechanical Engineering Formulae

Posted by on Nov 8, 2015 in Mechanical Engineering | 0 comments

There are many important Mechanical Engineering Formulae, considering the fact that physics as a subject is very wide and certain areas of physics draw connections from other areas of the same. The Formulas of Physics are categorized topically.

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# Section A of Mechanical Engineering Formulae

Mechanical Engineering Formulae for power Power is work done per unit time. The unit of power in Mechanical Engineering Formulae is ‘watt’ or ‘horsepower’; 1 horsepower (hp) = 746 Watts

Power = work/ time; P = W/ t.

Since work is energy consumed over a certain distance, time is also a factor and thus power can also be defined with the confines of energy, i.e.

P = E/ t

Mechanical Engineering Formulae for work From the knowledge of the law of conservation of energy, it is obvious that energy is always conserved; it can be transformed thou.

The product of a force and the displacement from its original position is called work. If one is pushing a heavy block across a room, then the further one moves, the more the work one does in Mechanical Engineering Formulae.

I.e. work = force × distance moved

W = F × S

Energy on the other hand comes in many ways. Those that are discussed here are kinetic energy and potential energy. For normal kinetic energy;

Transitional kinetic energy = (mv2)/ 2

Rotational kinetic energy = (Iw 2)/ 2

For rotational kinetic energy in Mechanical Engineering Formulae, I is the moment of inertia of an object (it is easier to understand moment of inertia by considering it to be similar to mass in transitional kinetic energy) and w is the angular velocity of the object. For potential energy;

Gravitational potential energy = mgh, where g is the gravitational pull and h the height of the object from the ground in Mechanical Engineering Formulae.

Elastic potential energy = (k L2)/ 2, where k is spring constant and L the length of spring.

Section B in Formulas of Physics

## Mechanical Engineering Formulae for circular motion

Given that V is the tangential velocity of an object, a is the centripetal acceleration, F is the centripetal force acting on the object, r is the radius of the circle of rotation and m the mass of the object;

a = V2 / r

F = ma = mV2/r

Mechanical Engineering Formulae for Gravitation

Kepler’s Laws
These laws in Mechanical Engineering Formulae major on the behavior of space i.e. their movements and are as follows: -

• The orbit of any planet is elliptical and has the sun at one of its foci.
• Each planet’s movement is in such a way that the imaginary line joining it and the sun sweeps out equal areas at equal periods.
• The square of the period of revolution any planet about the sun is proportional to the cube of its mean distance from the sun in Mechanical Engineering Formulae.

Newton’s law of universal gravitation

Every particle in the universe attracts another with a force directly proportional to the product of their masses and inversely proportional to the square of their separation.                                                  Therefore, for Mechanical Engineering Formulae if F is the force, g is the acceleration due to gravity, G is the universal gravitational constant (6.67×10-11 N.m2/kg2), m is the mass and r is the distance between two objects, then;

F = (G m1 m2)/ r2

Acceleration due to gravity

Acceleration due to gravity differs with the position on the earth’s surface in Mechanical Engineering Formulae. Outside the earth, the acceleration due to gravity is the same as it would be if the entire mass of the earth were to be concentrated at its center. Given that the acceleration due to gravity is g’ at a radius r outside the earth, the earth’s radius being re and the acceleration due to gravity at the earth’s surface g;    g’ = (re2/ r2) × g
Inside the earth, the parameters are different. If r represents the radius of the point inside the earth, then;

g’ = (r/ r) × g

For the formulas above in Mechanical Engineering Formulae, the acceleration due to gravity g’ equals the acceleration due to gravity due to the earth’s surface g.

### Conclusion on Mechanical Engineering Formulae

The above Mechanical Engineering Formulae are well derived and an important part of engineering.