Problems involved in escaping earth

1) Earth's Gravity

The first and foremost problem to be dealt by any man aspiring to start on his voyage to space is gravity.

Earth is a pretty massive object and thus any object on the surface of the earth (irrespective of its size) experiences a very large pull by earth and hence virtually remains bound to earth.(see physics world- Newton 's gravitational law) (not a part of site tour)

So as to break these bonds with earth, the object attempting to leave earth must be given a certain velocity called as the escape velocity. (See physics world) (not a part of site tour)

The value of escape velocity is 2.38 Km/s If the object doesn't attain escape velocity, it will either crash back into the Earth, or orbit around it, as satellites or space shuttles do.

By Newton 's first law, any mass whose motion is accelerated decelerated or has its direction changed will resist this change by developing reaction force.

Additional energy must be supplied to the object, keeping these forces in consideration.

2) Atmospheric Resistance

Another problem encountered while ascent is resistance of atmosphere. Air resists moving objects. As the velocity of this moving body increases, the resistance also increases.

So additional energy (energy that the space vehicle requires for overcoming air drag) must be supplied to it along with the energy required to overcome gravity and to travel in free space.

These problems must be taken into account when the space vehicle is being constructed.

Now let us see the fuel which is used to provide thrust to space vehicles.