1. The problem statement, all variables and given/known data A man that has an ordinarily weight of 780 N stands on a libra on the equator. 2. Relevant equations What is the weight measured by the libra? 3. The attempt at a solution I thought it was simple, so I just did: P = m * g Since it gives me P I can simply do: m = P / g = 780 / 9.81 = 79.51 kg But looking at the solution on the book it says that it's 0. Did I do something wrong?