A trebuchet was a hurling machine built to attack the walls of a castle under siege. A large stone could be hurled against a wall to break apart the wall. The machine was not placed near the wall because then arrows could reach it from the castle wall. Instead, it was positioned so that the stone hit the wall during the second half of its flight. Suppose a stone is launched with a speed of Vo = 28.0 mls and at an angle of 80 = 40.0. What is the speed of the stone if it hits the wall (a) just as it reaches the top of its parabolic path and (b) when it has descended to half that height? (c) As a percentage, how much faster is it moving in part (b) than in part (a)?
Obama’s DNC Address On behalf of the great state of Illinois... (APPLAUSE) ... crossroads of a nation, land of Lincoln, let me express my deep gratitude for the privilege of addressing this convention. Tonight is a particular honor for me because, let's face it, my presence on this stage is pretty unlikely. My father was a foreign student, born and raised in a small village in Kenya. He grew up herding goats, went to school in a tin- roof shack. His father, my grandfather, was a cook, a domestic servant to the British. OBAMA: But my grandfather had larger dreams for his son. Through hard work and perseverance my father got a scholarship to study in a magical place, America, that's shown as a beacon of freedom and opportunity to so many who had come before him. (APPLAUSE) While studyi
