Question

a plastic cube is released in water will it sink or come to the surface of water

Answer 1

The plastic cube if released in water does not sink and rather floats on the surface.

This called the phenomenon of buoyancy.

Plastic is water repellent object and it has high rates of buoyancy, when compared to other objects.

As plastic is lighter than the water it tends to float on the surface. If we try the same experiment with glass cube, the cube sinksas its weight is more than the liquid in which its released.

Answer 2

If the specific gravity of the water is 1, the plastic will float or submerged depending on the density of the material.

In case, the physical quantity is extremely high, the volume of the displaced water cannot exert sufficient buoyant force on the body.

Therefore, if the up thrust is not greater than the weight of the body, it will get submerged.