III. Structured Questions
1. a) How does the sighting of a ship from the seashore prove about that the earth is a shape?
(b) State briefly the Bedford Level Experiment
(c) Give a geographical reason for each of the following:
(i) The sunrise and sunset occur at different times at different places
(ii) The carth is not a perfect sphere
(iii) Venus is hotter than mercury
Answers
Answer:
a.=While standing at the seashore, watching an approaching ship, we first see only its mast. Then, as it comes closer, we can see the deck in the middle, then its funnel, and finally the hull comes into full view. This can only happen when the earth's surface is curved. Thus, it is proved that the earth is round in shap.
b=The Bedford Level experiment is a series of observations carried out along a six-mile (9.7 km) length of the Old Bedford River on the Bedford Level of the Cambridgeshire Fens in the United Kingdom, during the 19th and early 20th centuries, to measure the curvature of the Earth.
c=(i) The sunrise and sunset occur at different times at different places because the earth rotates from west to east and therefore, people in the east can see the sun earlier than those in the west.
(ii) The earth is not a perfect sphere because the diameter of th earth varies at the equator and at the poles. This difference is due to the centrifugal force of the earth's rotation at a great speed which forms a bulge at the equator and a compression at the poles.
(iii) Venus is hotter than mercury because Venus is mainly composed of carbon dioxide which produces Greenhouse effect on the surface of Venus. Thus, the temperature on its surface remains very high.