Suppose if we measure the time lapse between the two Sunsets by sitting in the beach, from this we can estimate – (1) The distance between the sun and the earth (2) The depth of the ocean (3) The radius of the earth (4) The radius of the sun
(3) The radius of the earth Explanation: A method is described whereby, using primitive equipment anyone can measure the size of the earth to an accuracy of order of magnitude 10% by observing two sunsets in the space of a few seconds.