A given solid is weighed in air using a spring balance. It is then weighed separately by immersing it fully first in vessel containing tap water and then in water containing salt solution. What would be the reading of the spring balance and why?
Answers
Archemedes principle: When a solid is immersed in a fluid, then the loss of weight of the solid is equal to the weight of fluid displaced by the immersed portion.
The solid experiences an upward force called buoyant force, which is equal to the weight of fluid displaced by immersed portion.
As the buoyant force is acting in upward direction, which is against the gravitational force (weight), the solid weight becomes less and the reading of the balance also becomes less. So, more is the buoyant force, less is the reading of spring balance.
The buoyant force acting on the solid depends on the factors such as density of fluid and volume of solid.
As density of salt water is highest among the given options, the buoyant force is maximum in the case of salt water and the reading of spring balance would be least in this case.
Ans: Option - (c)