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The circular groove is provided in a saucer for placing the tea only to prevent the cup from falling over in the case of sudden shocks. Other reason could be to provide support to the cup, or else the cup will fall when we change our direction due to Inertia of Direction.
Water in the Earth system is influencing all aspects of life on Earth. ... The returning water falls directly back into the oceans, or onto land as snow or rain. It soaks into the soil to move into the groundwater or runs off the Earth's surface in streams, rivers and lakes, which drain back into the oceans.