Show that the escape velocity of a body from the earth's surface is root 2 times its velocity in circular orbit just above the earth's surface.

Dear Student ,
Orbital velocity of a satellite is given by the minimum velocity of a satellite which rotate in a orbit around the earth near the earth's surface .
So orbital velocity is , 
v0=GMr=RgR+hwhere M is the mass of the planet R is the radius of the planet and h is the height of the satellite near the earth's surface .Now , if the satellite is revolving near the earth's surface then ,(R+h)=-RNow orbital velocity , v0=gR.......(1)Again escape velocity is the minimum velocity with which a body has to be projected vertically upwards from earth's surface so that it just crosses the earth's gravitational field .So , escape velocity of an object is ,ve=2GMR=2gR  ..............(2)Now from equation 1 and 2 we can write that ,ve=2v0
Hence it is proved .
Regards

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