Question

A metal solid cylinder tied to a thread is hanging from the hook of a spring balance. The cylinder is gradually immersed into water contained in a jar. What changes do you expect in the readings of spring balance? Explain your answer.​

Answer 1

Hint: In order to solve this question we should have a sheer knowledge about upthrust. The question says that when a metal solid cylinder tied to a thread hanging from the hook of a spring balance is gradually immersed into water contained in a jar, what changes happen in the reading of the spring balance.

Complete answer:
A spring balance is used to measure the weight of an object by opposing the force of gravity acting with the force of an extended spring. When the cylinder is gradually immersed into water it experiences upthrust, upthrust is nothing but buoyant force. buoyant force is an upward force that is exerted by a fluid which opposes the weight of a partially or fully immersed object. This is based on the Archimedes principle.
When a metal solid cylinder tied to a thread is hanging from the hook of a spring balance is gradually immersed into water contained in a jar we can see that the reading on spring balance decreases this is because and upward force is applied by the water and both the forces try to nullify each other which finally result in the reducing the gravitational force by the buoyant force or the upthrust and weight of the cylinder appears to be lighter.

Note:
Many people confuse between which type of buoyant is applied in the above question as we there are there type of buoyant force positive,negative and neutral positive applied on mass that float , neutral mass of object and liquid are equal and negative when mass sinks here negative buoyant force is applied as metal objects sink in water.