sciencecapsules

                      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 a

    Say, you are dropping a ball.  The height it had descended at the time 't' is given by the formula 1/2gt^2.  Here g=9.8 acceleration due to gravity. S= 1/2gt^2 1/2g =9.8/2 =4.9 hence S= 4.9t^2     The simple formula gives the distance fallen at any instant 't'.  The distance increases as the square of the time since the ball accelerates continuously due to gravity.  This is the meaning of the formula which we are going to explore.  You understand that y=x^2 is similar to that formula. 1. Let us plot a curve for this equation.-figure 1   We get a parabola, an important shape in math and physics.  Here, for  every y, there are two values for x.  x= -2 and +2, both satisfies the equation. y= (-2)^2=(+2)^2 =4 This kind of equation is called quadratic equation in Algebra 2.  If x^2=y or x^2 =-1, what is the solution.  X can be root of minus one. But "root of -1" does not exist in real numbers.  So we call it imaginary number and denote it by letter

            Consider the  pole- vault  jumpe r .     S uppose he falls on a hard floor, you know what will happe n ?       He falls on a foam bed that cushions and sags as he hi t .     O n a hard floor, he will experience heavy force   a ll o f   a sudde n .     I t will cause him injurie s .     O n a cushion floor, the time of force acting on him is elongate d .     H ence, the average force acting on him per second decreases rapidl y .     H e can comfortably bear that mild force.        To save lives:   "L engthe n  the time of force acting on the human body".       On a sudden  impact,  car's air bag is inflate d .     I t will cushion and save u s .     T he car's engine,  front cover   and bumper are  in front   o f   u s .     O n  a  crash, first they crumble saving our legs.            For the same reason, rest rooms are attached at both ends of the train compartment.       When the cricket  player catches  the ball, he lowers his hands to reduce the impact