Options: necessary centrifugal force may be obtained from the horizontal component weight of the train, to avoid frictional force between the tracks and wheels, necessary centripetal force may be obtained from the horizontal component of the weight of the train, the train may not fly off in the opposite direction
Which of the following agencies related to the United Nations is concerned with promoting the growth of international trade and equilibrium in balance of payments?
Options: United Nations Industrial Development Organisation, International Development Association, International Bank for Reconstruction and Development Organisation, United Nation Development Programme
Benjamin Franklin was a prolific inventor. He invented the lightning rod, the Franklin stove, studied electricity, discovered the Gulf Stream, started the first library, and on and on. Among his many other inventions, what musical instrument did he invent?