وَإِذَا الْجِبَالُ سُيِّرَتْ (3)
(81:3) when the mountains shall be set in motion, *3
*3) In other words, the earth also will lose its force of gravity because of which the mountains have weight and are firmly set in the earth. Thus, when there is no more gravity the mountains will be uprooted from their places and becoming weightless will start moving and flying as the clouds move in the atmosphere.