In this chapter, we studied idealized cases of balls rolling down smooth planes and objects falling with no air resistance. Suppose a classmate complains that all this attention focused on idealized cases is worthless because idealized cases simply don’t occur in the everyday world. How would you respond to this complaint? How do you suppose the author of this book would respond?

Solution 42E (a) Even though the ideal situations are not strictly accurate, the ideal situation gives us a very good model to understand how things work. Sometimes the ideal situations are so close to the real situation, that the ideal approximation gives us the fairly accurate result, which, if we drive using the real situation, will be very complicated but will not add more significant value to the result. For example, suppose a heavy ball is falling in the earth’s atmosphere. In this case, we can consider that the ball is falling freely under gravity and use the ideal situation. The result will not be very different from the real situation as the air resistance in the case is negligible. In some cases, even though the ideal situation does not match closely with the real situation, we can still use the ideal situation to calculate the approximate result, then later add the correction to it to get a proper result which will match to the real situation. So the ideal situation makes the understanding the system easier, makes it easier to compute the results and we can find out the deviation from the ideal situation and make the corresponding correction to the final result to get result similar situation. Hence ideal situations are important. (b) I think, the author of this book would have replied in the similar way as I have replied.