Skip to main content

WHY WE USE 'ROTATIONS' EVERYWHERE? 

        

            In this world, rotations are more common than the linear motion.  The planets revolves and spins; the electron circles; the wheels roll; the motor and the engine runs; even opening and closing a door is a partial rotation.

     Force required :  Newton says that if a body is given a push, it will only move in a straight line.  Hence, to keep the body in rotation, a force must act and it should act continuously.  A force must act from the moving body towards the center ceaselessly.  It is centripetal force.
     The sun keeps all the nine planets revolving around itself because of gravitational pull which acts as centripetal force.
     The electron keeps circling the nucleus because of electrical force of attraction.  The electrical motor works because of magnetic Lorentz force.

      The moment:  Next, take a DVD.  Put one ink dot near the center and another ink dot near the edge.  Rotate it.  You can observe that the dot near the center moves fast and dot at the edge moves less fast.  Hence, distance from the center or axis of rotation plays very important role in rotatory motion.  This 'distance' is always multiplied with quantities like mass, velocity, momentum, force, inertia in rotating particles and bodies.  Multiplying with 'distance' is known as finding 'moment' in physics.
     Consider a large carriage door.  If you push it at the edge you can easily close and open.  But, if you push it near the joint (axis of rotation), it is even difficult to move the door a bit.  That is why we find the  'moment of force' to get the real effect of the force.

    Stability:  Rotating wheels keeps its axis of rotation stable.  Examples: spinning top, two wheeler, cycle, the toy-fidget spinner.  When they are in motion, they cannot be brought to the ground       easily(gyroscope effect)

    Energy store:  A rotating giant wheel cannot be stopped 'all of a sudden' due to rotational inertia.  It will continue to rotate for some time.  So a rotating heavy wheel act like mechanical battery storing mechanical energy.  This concept is widely used in automobiles.

    Compactness:  Rotation is a compact motion.  It can be contained in  an atom; in a motor assembly; in a car; in a DVD player; in a cyclotron; in a gyroscope and so on.  Today, people even go for a nano molecular motors.  Hence go for rotation always.

   Note:  Electricity is generated mainly using rotations.  Because rotations are easy to execute.   

Comments

Post a Comment

Popular posts from this blog

THE EARTH, A SUPER ORGANISM

     JOIN MY COURSE: "Become a programmer in a day with python"       A man called 'love lock' (what a name) proposed a theory called Gaia theory, named after Greek Goddess.      It says, "Earth is a self-regulating organism like a human being.  The organic life in it interacts with in-organic matter and maintains atmosphere, temperature and environment".  Hence the earth is still suitable for the life to thrive.      Imagine, in a particular place, there are lot of flowers.  Some flowers are white and some are darkly coloured.  We know, white reflects light and heat while dark absorbs the same.  White flowers can thrive in hot climate.  But dark flowers requires cold climate.  The absorption and reflection balances and the environment reaches average, warm temperature at which both the flowers can co-exist.  This is the essence of "Gaia" theory.      On our earth, ...
3 comments
Read more

THE PARABOLA

          A jet of water shooting from a hose pipe will follow a parabolic path.  What is the so special about parabola.    Y= x^2 Draw a graph for the above equation.  It will result in a parabola.  This parabola is also called unit parabola.  Any equation involving square will yield a parabola. Example:  Y = 2x^2 +3x+3 (also called quadratic equation)    X= 2 and -2, both  satisfies the equation 4 = X^2.  Parabolic equations always have two solutions.     Any motion taking place freely under gravity follows parabolic path. Examples:   An object dropped from a moving train,   A bomb dropped from flying plane,  A ball kicked upwards.      If a beam of light rays fall on the parabolic shaped mirror, they will be reflected and brought to focus on a point.  This fact is made use of in Dish Antenna, Telescope mirrors, etc.   ...
Post a Comment
Read more

DISORDER IS THE "ORDER OF THE DAY"

         Imagine a balloon full of air.  The air molecules are moving randomly inside the balloon.  Let us pierce the balloon with a pin.  The air rushes out.  Why should not the air molecules stay inside the balloon safely and ignore the little hole?  That is not the way the world works.  The molecules always "want to occupy as many states as possible".  Hence the air goes out in the open to occupy more volume.   The things always goes into disorder (entropy) and the disorder increases with time.  The above statement is what we call "second law of thermodynamics".      Consider a cup of coffee on the table. Suppose the heat from entire room flows to your cup of coffee, the coffee will boil and the rest of the room will freeze.  Freezing means bringing things to order and arrangement.  It violates the second law.  Hence it will never happen.  Hence heat must flow from high ...
Post a Comment
Read more