How to decide which object will float or not in water?

Object will float or sink depends on its own density and the density of the liquid it is placed in. In the case of water, an object with a density less than 1 g/cm3 will float. In other we can say that A 1 g object will sink until it displaces 1 g of water. This is independent of its size or shape. Since water has a density of 1 g/cm3, a 1 g object will displace 1 cm3 of water. read less

This depends on the density of object. If the density of object is more than density of water it will sink and if the density of object is less than density of water it will float. Density means tightness of the intermolecular bonding of an object. floating and sinking also depends on how much water an object can displace. if an object displaces an amount of water equal to its weight, than it will sink. For example, a stone and a piece of thermocol with same dimensions, the volume of both objects is same but their density is unequal. Density of stone is more than the piece of thermocol and water and it can displace amount of water equal to its weight. Therefore it waill sink in water. Whereas density of thermocol is less than that of stone but more than water but still it does not sink in water because it can not displace equal amount of water as its weight. this is because, The thermocol contains large number of tiny spaces filled by air. This makes its average density lower than the water. Therefore it floats. read less

Blow up a balloon and float it on water. It will not sink very far because it is not very heavy. If you look really close, where the balloon touches the water, you can see a little dent in the water under the balloon. That's the place where the water is pushed out of the way. Floating or sinking has to do with the amount of water pushed out of the way. Any boat will sink if you put enough stuff inside it Small, heavy things like a marble or a rock cannot float because they cannot push enough water out of the way to be the same as how much they weigh.So remember, anything that floats weighs the same as the water pushed out of the way. read less