PROJECTILES SATELLITES AND GRAVITY Satellite and Circular Motion

PROJECTILES, SATELLITES AND GRAVITY Satellite and Circular Motion

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GRAVITY n n The force of attraction between any two objects with mass. A field force (a non-contact force) A universal force (Gravity is everywhere) The weakest of the 4 fundamental forces

In orbit around the Earth, Astronauts experience 90% of the gravitational force you experience at the Earth’s Surface

Gravitational Force Field

Einstein’s View of Gravity mass deforms the space-time fabric, Earth follows the contour (even light follows the contours of space-time)

Gravity n n Fg is the force of gravity and your weight All objects with mass are surrounded by a gravitational force field

n Gravity depends upon the mass of the objects and the distance between them Gravity More mass, more gravity d M 1 M 2 Increase distance, decrease gravity

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

Law of Universal Gravitation n n Newton’s law of gravity Fg = m 1 x m 2 x G d 2 G is the gravitational constant 6. 673 x 10 -11 N x m 2/kg 2 Can be used to calculate the gravitational force between any two objects

Universal Law of Gravitation Gravity depends upon --Mass --Distance between masses n Differences in the intensity of gravity can be calculated using Newton’s Universal Law of Gravitation n G is the gravitational constant F 2 = G m 1 m 2 -11 3 G = 6. 672 × 10 m /(kg sec ). d 2 n Measure distance from center of object. n