IB Prized Writing Sevenoaks School IB Prized Writing 2014 | Page 121

Nina del Ser - Mathematics 16 | octopus v s r s   Ω ps v p r p Ω p v p 1 v s 1 Ω s 1 r s 0.5 Ω p  1 r p   1 figure 37 At some point in time, the two velocity vectors v p and v s will inevitably be parallel to each other, either pointing in the same direction or in opposite directions to each other. In the first of these cases, the seat will be traveling at maximum speed, whilst in the second, it will be going at minimum speed. In order for loops to occur, the seat must, in a sense, travel “backwards”, since it needs to return to a position (the point of intersection) in which it was several moments prior to that. This is only achievable when the net velocity is negative, which can occur at the minimum value only when |v s |>|v p |. If |v s | |v p | the seat will “freeze” in space momentarily when the two vectors oppose each other, resulting in a “� spike”. The last case, in which |v p |>|v s | should therefore produce curves that don’t loop or spike, instead follow smooth lines. The following tests, in which angular speeds have been kept constant but rotor lengths have been altered in order to increase or decrease the values of the velocity vectors, appear to support this hypothesis (Note that these pictures are not at the same scale): 120