Students can usually say that it has something to do with circles but beyond that, there is mostly little understanding. The concept of pi is no more complex than this, yet it is rarely understood. The amazing fact that pi is the same for all circles, large or small, is still another thing few understand. We hope to provide an activity that will help your students understand the meaning of pi in what follows. It is interesting to speculate about the discovery of pi.
Pressure is simply the ratio of force to the area on which the force acts.
Or, pressure is force per area. Most agree that they can't . Most agree that they can. The difference in these two cases is the difference between force and pressure. Even if the force exerted by your thumb is the same in both cases, since the area of the point of the tack is so much smaller than the area of contact made by your thumb, the pressure at the end of the tack is much larger than the pressure exerted by your thumb alone.