[6] A man is at sea miles distant from the nearest point of a straight shore and he wishes to get to a place miles distant from the nearest point the road lying along the shore. He can row and walk. Find at what point he ought to land to g…

[5] The gas envelope of a divigible balloon has the form of a surface of revolution. The parts of the generating line are parabolas with their axis to the axis and their vertices at respectively. The part is a straight line parallel to the…

[1] （物理學）State clearly what distinction you would draw between mass and weight.[2] （物理學）A current is passed through a wire of 10 ohms resistance and the difference of potential between its extremities is 100 volts. Find how many …