Don’t Try to Escape (Loving relation between light and black hole) :
Introduction
The motion of celestial bodies is related to the law of gravitation. We all know what is gravitation .The expression is -
where m1 and m2 are two masses separated by a distance r and G is gravitational constant [6.67×10^–11 N-m²/kg²].
Escape velocity
When a ball is thrown up from a planet it goes up to a certain height and then returns .But if the ball is thrown up with a certain velocity so that it will be able to overcome the gravitational force and never returns. Then this velocity is called escape velocity(Ve).
Where M is the mass and r is the radius of the planet. That means escape velocity doesn’t depend on the mass of the object which is projected.
■ Think you are playing with a ball and throws it up with a velocity greater than or equal to the escape velocity and you are waiting to catch it .what will be you age when you catch it!!
Black Hole
Consider a spherical body of mass M and radius R .Suppose,due to some reason the volume starts decreasing while the mass remains same.Then the body becomes highly dense and escape velocity from such a dense body will be very high. Suppose the radius is so small that
where c=3×10⁸m/s ,speed of light. The escape velocity for such a body is equal to or greater than the speed of light. So we have to throw any object with a velocity equal to or greater than the speed of light. Otherwise it will return back. But according to Theory of Relativity it is impossible to achieve a velocity greater than ‘c’ for any material object.So nothing can escape from such dense material. Such objects are known as black hole and even light cannot escape from it.How loving relationship!!