Question

A vessel filled with water is kept on a weighing pan and the scale is is adjusted to zero. A metal block of mass M M and density 2000 kg per metre cube is suspended by a massless spring of spring constant k. This block is submerged inside into the water in the vessel without touching the bottom. The reading of the scale will be
1) equal to upthrust applied by the liquid on the block
2) equal to weight of the block
3) less than the upthrust on the block by the liquid

Please give reasons.

Answer 1

Answer:

The reading on the scale will be equal to upthrust applied by the liquid on the block

Explanation:

Things to note:

1) The scale is adjusted to 0 after the vessel and water is put on the weighing pan.

2) When the object is placed in water it experiences upthrust equal to its weight in water.

The volume of the solid is equal to the volume of the water displaced.

Assuming the solid displaces V m³ of water then the weight of the vessel is given by :

Weight = rho × V × g

rho = The density of the solid

V = Volume of water displaced = volume of the solid

g = acceleration due to gravity

This equals to the upthrust which is the force that water applies to the block.

The reading on the scale is the upthrust.