 If you have ever drawn out some water from a well through a bucket, you must have felt that the bucket full of water feels lighter when inside the well or inside the water. But when you pull it out of the water, it starts to feel heavier. Why does that happen? We can even experimentally verify this. Here I have a toy and I have attached it to a weighing scale, which can tell me the weight of the toy. Right now the reading is 0.16. But notice how the reading decreases when the toy goes inside the water. There you go, look at it, how it is decreasing. And the toy also starts to feel lighter and lighter. Now, alright, let's understand this by submerging a glass slab inside a bottle with some water. So, here I have some water and here I have some, here I have a glass slab. This glass slab has a weight. Now, weight is a type of force which acts in the downward direction. Heavier objects have more weight, which means they will pull my hand in the downward direction with a greater force. Now, I will place this glass slab inside the water so that it is completely inside the water. As soon as I do that, I feel that the glass slab has become lighter. So, what is happening here? Well, it turns out there is a new force, there is a new type of force that acts on any object inside water. And that force is called buoyant force. This force acts in the upward direction on the object. Now, as a result of this, the total force which acts in the downward direction reduces. So, now less force is pulling my hand in the downward direction and the glass slab feels a little lighter. So, buoyant force acts on objects when they are inside water. Even if the object is not completely inside, still buoyant force will act on the object. And the object will feel a little lighter. So, can you now explain why does the bucket full of water feel heavier outside water and lighter inside water? Try explaining it.