Question

explain why the surface of mortar and pestle(silbatta) used for grinding is etched again after prolanged use​

Answer 1

Answer:

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After prolonged use, the mortar and pestle loose the roughness, due to which frictional force reduces and it does not work properly. So, we have to etch it to makelt rough again.

Answer 2

Archimedes' principle is named after Archimedes of Syracuse, who first discovered this law in 212 BC.[4] For objects, floating and sunken, and in gases as well as liquids (i.e. a fluid), Archimedes' principle may be stated thus in terms of forces:

Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object

—with the clarifications that for a sunken object the volume of displaced fluid is the volume of the object, and for a floating object on a liquid, the weight of the displaced liquid is the weight of the object.[5]