 Have you ever hammered a nail like this? No, right. You must have hammered a nail like this. Only then it can punch you through the wood. But why? You might say that this end is more pointy. Let's take one more example. We use knives to chop tomatoes, right? But have you ever thought of chopping tomatoes with your finger? No, right? And you might say, Well, the finger is not as sharp as a knife. We will answer these questions in more detail with the help of an activity. So for this activity, I have some flour and this box with some chalks in it. I will place the box like this horizontally. And when I do that, I see that it has left a mark on the flour. And there is this much depth to the mark. Now I will leave the box like this, that is vertically. And I again see that the box has left a mark on the flour. Now there is this much depth to the mark. In which case is the depth more? If we compare these two cases, we can see the mark has a greater depth in this case. Why did that happen? Let's dive deeper. Now every object has a weight of its own, right? Like the box of chalks. When the box was kept horizontally, the force was divided over a larger area. And when it was kept vertically, it was divided over a smaller area. Now because the same force of weight was divided over a larger area in the case on the left, the amount of force that appears or acts on any one point on the flour is very small. For the case on the right, the amount of force that appears or acts on any one point on the flour is larger. So if we have the same force, then the depth of the mark is less when the box was kept horizontal. And the depth of the mark is more when the box was kept vertical. It matters how concentrated the force is. Same force is divided over a larger area in the first case. So it is not that concentrated. But when the same force is divided over a smaller area, then it is more concentrated. And this is what we call pressure. Pressure can be thought of as how concentrated your force is. We can even calculate pressure. Well just like we saw that we are basically calculating how much force gets divided over the area. Mathematically also, pressure that is P is calculated as the force divided by the area. And its units will be Newton per meter square. So in the first case, when the area was very large, the pressure was small. But in the second case, when the area was small, the pressure became large. Now let's come back to our original question. Why do we hammer a nail with a pointy end at the bottom? Well then force is concentrated over a very tiny area. But in the case on the right, the same force is concentrated over a larger area. And as a result, if you now compare the amount of force that appears on the same spot as before, the force has reduced a lot, right? Because it got divided. The contact area was very small in the first case. So the pressure was very high. And the contact area was large in the second case. So the pressure is very low. Similarly, when you use a knife and put a force, then all the force gets concentrated into a very tiny area. Because the knife is very sharp. So that means the tomato experiences a large pressure. But because your finger is not so sharp, the base area of a finger is so wide, at least compared to the knife, that entire force gets divided over a large, larger area. And as a result, the amount of force that appears on the same slice of tomato as before is small. So now the tomato experiences less pressure.