The escape velocity

Even after all this controversy about gravity a lot of troubles seems to be unsolved. A throwback to the moment when we talked about the big bang, obviously the cosmic inflation caused all the condensed matter to be projected and the space to be expanding at an unbelievable speed and as always to simplify the idea am going to explain briefly another basic concept of physics.

Let's suppose that I have a stone in my hand that I wanted to throw up vertically, to do that I have to

give it an initial speed, according to the Newtonian law at the state of equilibrium the object is submitted to 2 forces that are its weight and the plan reaction of my hand that are completely opposite so their sum is null. The extra motor force in the same direction of the plan reaction frees the object from its static state but what happens then?

The stone continues to go up and slows down due to the air friction and weight, at a certain moment, it stops for a fraction of the second mid-air we call that the maximum amplitude, then it falls down again.

But what happens if we throw the rock really hard enough?

there is a certain boundary of speed which is called the escape velocity and if we give an object such a speed it can overcome the resistant forces, in this case, the stone will have enough strength to quit the earth's atmosphere and go to space. This is what made rocket science possible and gave possibilities for spaceships to quit earth.

The earth escape velocity is approximately about 11km/sec, give any object such a speed and you can kiss it goodbye!

This value varies depending on the gravity of planets because of P=mg, knowing that g being the acceleration gravity ( g=MG/r²), it depends on the planet's weight so it varies from a planet to another. For a black hole, the escape velocity is about 300.000km/s did you somehow recognize this value?! Sure you did it's the light celerity that's why even light cannot escape a black hole !!