Why do somethings float

That's another reason why even big ships don't sink if they have the right shape. You can test this out yourself. Try making a boat with a flat bottom using tinfoil. Does it float? What happens if you start putting pennies or pebbles inside your boat? What happens if you crumple your tinfoil boat into a ball? BY Autumn Spanne.

Generally the more of the outside of an object that is touching the water the more buoyant it is. Water pushes back up against objects so the more surface area an object has the more water pushes back against it helping it to float.

When an object floats, it pushes water out of the way displacement. Have you ever noticed that when you climb into a bath the water level rises? This easy activity demonstrates how reducing the density of a heavy object allows it to float. Place the bubble wrapped ball on the surface of the water, you should find it now floats. Although the bubble wrap makes the ball weigh a little more, it also displaces extra water making the ball more buoyant. The pockets of air in the bubble wrap mean that the ball and bubble wrap together are less dense than the water, which means the ball floats!

Can you think of a different way to make the ball float? What if you made it a boat with plasticine? Do you know what density means? Well everything around us is made up of tiny molecules.

In some objects these molecules are jam packed together, and in others they are loosely packed together. This is actually what density means. How does this sink and float work?

Some boats are massive, and would seem very dense, so how do they stay afloat? Now comes buoyancy, which is the opposite of gravity. But what is buoyancy? Think about what happens when you put an ice cube into a glass of water. As the ice cube displaces moves some of the water to make way for itself, the water level rises and the ice floats partially in and out of the water.

Mass is a characteristic of a particular object. Volume is also a characteristic of a particular object. Density is an intrinsic property of a material. For deciding about objects, again the target concept is the compound property of density, not the contributing concepts of mass or volume alone. For 6 Resources. Demonstration: This rough method can produce a difference of mass of at least 8 g. With enough apparatus it could be done as Practical Activity The diver sinks when you squeeze the bottle, and rises when you let go.