Courses for Kids
Free study material
Offline Centres
Store Icon

Floating and Sinking

Reviewed by:
Last updated date: 20th Jul 2024
Total views: 209.1k
Views today: 6.09k
hightlight icon
highlight icon
highlight icon
share icon
copy icon

Introduction to Floating and Sinking Objects

Have you ever wondered about why some objects sink, and some objects float?

You might think that the bigger things sink and smaller things float, but this is not true! 

There are so many more reasons behind the mystery of the process of sinking and floating. Why do some objects float while others sink? 

Well, it’s all about something known as density. Do you know what float or sink density means? Well, everything around us is made up of some tiny molecules. In some objects, these molecules are jam-packed with each other, and in others, they are loosely packed together. 

Floating and Sinking Definition

If Something is More Dense than Water, will it Float? 

If an object is denser than water, it will sink when placed in water, and if it is less dense than water, it will float. 

The density is defined as a measure of how heavy something is compared to its size. If an object is denser than that water, it will sink when placed in water, and if it is less dense than that of water, it will float. The density is a characteristic property of a substance and doesn't depend on the amount of substance.

Different objects floating and sinking.

Different Objects Floating and Sinking.

What will Sink and What will Float?

We will learn this by doing one experiment.

Get a bowl or a bucket. And fill the water into it and collect a few objects around the house or from your garden. For example the objects like a piece of small wood, a stone, a sponge, an egg, a spoon, small balls or anything else that you can find around you.

Put these objects in the bucket or bowl full of water and observe what will sink and what will float. Now you’ll see that whatever objects sink are denser, and what floats are less dense. 

Write all your findings down.

Objects that are Sinking

Objects that are Floating

1) ______________








Experiment for checking the floating or sinking objects.

Experiment for Checking the Floating or Sinking Objects.


Well, everything present around us is made up of tiny molecules.

Let’s think for a minute about other bigger objects like a boat, or maybe even an airship. Why do things sink or float?

Some boats are very big and seem very dense, so how do they stay afloat? Well, the boat has to push the water aside, so there’s room for it. As it is so heavy, the heavy boats get pulled down by the force of gravity. 

Now think about what will happen when you put an ice cube into a glass of water.

As the ice cube moves some of the water to make way for itself, the water level rises, and the ice floats half in and out of the water.

The gravity pulls the ice cube down, and the force pushes it up. It totally depends on the gravity of how far the ice cube will stay in or out of the water. It works according to the pushing and pulling forces that are working against it.

FAQs on Floating and Sinking

1. What two forces are there when floating?

There are two forces that can influence an object's floating. The buoyant force, which is upward, and the gravitational pull, which is downward, both operate on the floating object. The object floats if the buoyant force balances the gravitational force or the weight force.

2. Does oil tend to float on water?

Oil always floats on top of water because it is less thick than water, leaving a film of oil on the surface. After a significant downpour, you may have noticed that some water puddles had an oily sheen floating on them.

3. Does a dead fish sink or float?

Since most fish are considerably denser than water, they sink right away after they die. They eventually become more buoyant, though, much like a drowned person, as gases are produced inside the body by bacterial decomposition. In most cases, enough gas gathers in the body cavities to cause the corpse to float like a blown-up balloon.

4. How does the shape of an object affect floating and sinking?

The shape of the hull allows the boat to displace a volume of water equal to the weight of the boat. Since much of the submerged area is air, the average density (total mass of the boat divided by the volume of water displaced) is less than that of water, thus allowing it to float.

5. Do scissors float or sink?

Scissors are heavy objects so they sink in water. All of the sinking objects have a density more than 1.0 g/cm3. Does mass or volume alone determine whether an object will sink or float? No, you need both mass and volume (mass divided by volume) to find density (needed to figure out if the object will sink or float).