Question

An object is suspended with a string the string gets stretched.When the object is completely immersed in water the extension of thread decreases.Explain why it so happens.

Answer 1

Dear Aisha76721,it happens because of the buoyancy force . The buoyant force is continuously acting on that body immersed in the liquid and that buoyant force is in the up direction , so that's the reason.
Although when the object is in air ,then also buoyant force is acting but its comparatively less than the buoyant force acting when its immersed in liquid

Hope u came to a conclusion

Best regards
Vatsalya

Answer 2

the bouyancy or uplift prodyced by water decreases the tension produced in the string.