Projectile Motion
*Object, moving in gravitational field, with gravity only force acting on it - moves in a parabolic shape
*Measured in two independent dimensions
oVertical - gravity effects
oHorizontal - remains constant though-out motion
*Galileo - formulas for projectile motion
oS = UT - Horizontal motion
oS = UT + ý AT2 - Vertical motion
Galileo analysis of Projectile motion
*Trajectory of projectile makes a parabolic shape
*Led him to consider reference frames
*Opponent believed in idea of geocentrism - stone would be left behind if Heliocentric
*Galileo explained - didn't fall away because shared the earths motion
oTower and stone shared the same horizontal velocity
oExperiment - dropped object from crows nest of ship - dropped down to base of tower whether stationary or moving at a constant velocity
*This led to Galilean relativity
o'The laws of mechanics are the same in a frame of reference that is at rest or one that is moving at a constant velocity'
Escape Velocity
*The necessary velocity needed to leave the earths surface
*Depends on gravitational acceleration of planet - hence mass and diameter of planet
*~11.2 km/sec on earth - not taking into account atmospheric friction
*Lower escape velocity - least likely planet has atmosphere
Newton and Escape Velocity
*Proposed the idea of artificial satellites
*Projectile launched horizontally from mountain -
oAs launch velocity increased, object would go further till crashing or till it follows ellipse of earth - orbit
Circular motion
*Motion of an object in circular path, with constant speed - uniform circular motion
*Speed same - however changing velocity and accelerating - direction always changing
*Change in velocity - directed towards centre of circle; centripetal force
*Uniform circular motion - centripetal force is always towards centre of circle
*Ac = MV2/R
*Orbit is acquired by lifting...
Space - Summary
Not bad, except that this "Summary" is still a little too lengthy... :p
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