Gravity
Gravity
Weight is a force. It is the effect of the force of gravity acting on the mass of a body producing, or trying to produce, an acceleration. Note the acceleration of 9.81 m/s2 is an average value on planet earth. It varies slightly from place to place but 9.81 m/s2 is acceptable for all practical purposes. The acceleration due to gravity is given the symbol g, therefore the expression:
F =ma becomes F =mg in calculations involving gravity.
On planet earth, the force F exerted by a mass of 5 kg=5×9.81=49.05 kN. Since the gravitational attraction of the moon is approximately 1/6 that of the gravitational effect of planet earth, the force F exerted by a mass of 5 kg =5× (9.81/6) =8.175 kN on the moon.