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The universal law of gravitation states that, ‘Every object in the universe attracts, every other object with a force which is directly proportional to product of the masses, and inversely proportional to the square of the distance between them.’, , , , The SI unit of G is N m? kg~? and its value is 6.673 x 10° ''N m? ke~?, , The strength of the gravitational attraction between two objects depends on two, factors:, , How big the objects are (how much mass they have) and, , How far apart they are., , 3. Free Fall, , ¢ With negligible air resistance, falling objects can be considered freely falling. objects, , of different shapes accelerate differently (stone vs feather), , , , 4 .To calculate the value of” g“(acceleration due to gravity), , or g, , The acceleration due to gravity is denoted by g., The unit of g is same as the unit of acceleration ms?, From the second law of motion, force is the product of mass and acceleration. F = ma, , For free fall, force is the product of mass and acceleration due to gravity., , , , GM,, F=mg or mg== a, GM, pe, , where M is the mass of the Earth and d is the distance between the object and the earth., , For objects near or on the surface of the earth d is equal to the radius of the earth R, GM, , F=mg or mg== 7