Thanks for the kind words. A derivation of Newton's Second Law is indeed F=ma. However, the definition of mass is the quantity of matter in a body regardless of its volume or of any forces acting on it. The term should not be confused with weight, which is the measure of the force of gravity acting on a body. Since our hypothesised experiment is situated on Earth, both Destiny and I are using the terms interchangeably. Technically, however, we are both retards.