Verily, Allah grasps the heavens and the earth lest they should move away from their places. Here His grasping is through gravitational force and their places is their orbits. Gravity of a heavenly body varies according to its mass. The value for earth s gravity is determined as 9.8 meters per second. A falling apple is credited with prompting Newton to discover gravity.
Force is chosen here to suit the context.
Whether to send a satellite up the space, despatch instruments to explore Mars or to send man to moon - the rocket to carry them can lift off the surface of the earth only if it develops a force exceeding earth s gravity. If only it reaches a vertical velocity of 11 km per second it could get rid of earth s grasp and enter outer space. If not, it will fall down back. This velocity, termed escape velocity of a heavenly body, depends upon its gravity. Holy Qur an was revealed in an age when even air flight by man could hardly be given a thought, let alone attempted.