earth is a kind of planet & mars is a kind of planet & earth is greater in mass than mars ->  earth is a planet that has a greater mass than the planet mars  earth is a planet that has a greater mass than the planet mars & as mass of a planet / of a celestial body increases , the force of gravity on that planet will increase ->  the force of gravity on earth will be greater than on mars  the force of gravity on earth will be greater than on mars & as the force of gravity increases , the weight of objects will increase -> objects will weigh more on earth than on mars because the force of gravity is greater on earth than on mars