(5-11)   ①   Starting from the requirement that

We know that F(k) = 0 when k is outside the range 0 to kmax and F(k) = c within this range. So we can rewrite this integral as:

Alternatively, we can get this graphically:

②   Because – as Nefertiti has been at pains to point out – the momentum is equally likely, for any value of k, to be positive or negative,  the mean value, <p> will equal zero.