GRAVITY Gravity Defined, Law of Universal Gravitation and Inverse Square Law
GRAVITY n n The force of attraction between any two objects with mass. A field force (non-contact force; surrounds) A universal force (Gravity is everywhere) The weakest of the 4 fundamental forces
Universal Law of Gravitation Gravity depends upon --Mass --Distance between masses As mass increases, so does the amount of gravity. As the distance between two objects increases, the amount of gravity decreases. n
Gravity n Gravity depends upon the mass of the objects and the distance between them More mass, more gravity d M 1 M 2 Increase distance, decrease gravity
Newton’s Universal Law of Gravitation Differences in the intensity of gravity can be calculated using Newton’s Universal Law of Gravitation n G is the gravitational constant G = 6. 672 × 10 -11 m 3 /(kg sec 2). n Measure distance from center of object. n F = G m 1 m 2 d 2
Inverse-Square Law n n n Changes in the intensity of gravity are caused by changes in the mass or in the distance between masses, and follow the inversesquare law. Electrical and magnetic fields, light, radiation, sound, gravity, and even spray paint. Systematic decrease in concentration or intensity due to spreading out. Intensity = 1 d 2 2 x further away means 4 x less gravity!! 10 x closer means 100 x more gravity!!