Question

a stone is suspended by an elastic string. why does the length of the string decrease when the stone is dipped in water?

Answer 1

Hey mate, here is your answer

When the stone is hanging freely , the rubber string elongates the maximum length . As it is partially immersed in water , the stone experiences a buoyant force due to the weight of the water displaced by the partially immersed part of the stone . Since, the buoyant force is directed upwards the apparent weight of the stone decreases which eventually results in slight decrease in elongation of rubber string . When the stone is fully immersed in water , the buoyant force now is larger than previous case . Now the volume of water displaced is equal to the volume of the stone and the weight of the stone decreases by an amount equal to the weight of the displaced volume of water . Thus , the apparent weight of the stone is now smaller than the previous case and the elongation of the rubber string decreases further .

I hope it helps you..........!