Activity Based Science Learning >A game with nails and balloons


Introduction:

We know that there is strength in unity. For example, if you ask your friend to break a piece of stick into two pieces he will readily do it. Next, give him four-five stick tied together and ask him to break them; surely, he will not be able to do it. We will see just the reverse of this happening in this game. You will see that while a single nail is able to deflate the balloon, a multitude of nails will not be able to deflate it. Does it mean that there is no strength in unity? 

Required Material:

Balloons, a large number of nails, a large and a small rectangular wooden seat

Procedure:

1.         First stick a large number of small nails on the large rectangular seat. The nail should be very close together and their heads should be visible with their piercing ends being fixed on the seat. In this way you will be creating, so to say, a bed of nails.

2.         Stick only a single nail on the smaller seat in the same manner.

3.         Next inflate a balloon and place it on the nail stick to the smaller seat. Press the balloon gently. Does the balloon get deflated? Usually, it will be deflated.

4.         Now inflate another balloon and place it this time on the bed of nails. Press the balloon gently. Does the balloon get deflated or not? No, this time the balloon is not deflated. Even if you press the balloon with force it does not get deflated. Think why is this so happening? 

Discussion:

In the first case when we press the balloon by placing it over a single nail, the balloon exerts a force on the nail. In this case, this force is exerted on a single nail only. The nail by way of reaction, also exerts an equal and opposite force on the balloon. This force is enough to puncture the balloon which, therefore gets deflated. In the second case, when the balloon is in contact with a large number of nails, the force exerted by the balloon (which is almost equal to the force in the first case) gets distributed amongst multiple nails. This means that, in this case, a very small force is exerted by the balloon on the individual nails. The force of reaction exerted by the individual nails on the balloon gets reduced proportionately and attains such a value that is not enough to puncture the balloon. We can also understand this as follows. The force acting on the balloon gets distributed over a large surface area and so the balloon does not get punctured. We can understand from this experiment that when a force is applied on a small surface area, then the pressure on that area is more and when the same force is applied on a bigger surface area the pressure decreases. 

In this experiment, if we apply a force equivalent to 10 kg on the balloon, than for the case when there is a single nail, the entire force gets exerted on it. The nail also exerts the full, 10 kg equivalent force, on a very small area of the balloon and punctures it of leading to the deflating of the balloon. However in case there are, say 50 nails then a force equivalent to 10/50 kg or 200 gm is exerted on the individual nails. These nails, in turn, each exert on the balloon a 200 gm equivalent force. This force is not able to puncture the balloon. 

Do and Think a little more :

Repeat this experiment by sticking instead of one, two, three and even more nails on the small seat and find out how many nails would be needed so that the balloon does not get deflated.                                 





 


Back on top ^