Question

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

Answer 1

When a plastic cube is released in water, it will come to the surface of water. The phenomenon behind this is called buoyancy.

According to this, buoyancy is an upward force exerted by a fluid that opposes the weight of an immersed object.

And plastic cube is less dense than the water. Thus it floats.

Answer 2

Plastic cube will come to the surface of water.

This is beacuse of the boyant force applied by the water on the cube.

Also, the sinking of floating is depended on the density of water as well as on density of cube.

If density of water is higher than the density of cube then cube will float, else sink.