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 + ½ 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 …showed first 75 words of 2183 total…

…showed last 75 words of 2183 total…time of 2.2us but found - lifetime is dilated to 49.2us Implications of time dilation and length contraction for space travel *Travellers will age more slowly to stationary observer *Time dilation - possible to travel to stars in one lifetime oHowever travelling at 0.999c - take 4.47 yrs to reach closest star; on return it will be 200 yrs later on earth *If speeds can be reached in excess of c (300c) possible to travel into past