You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 Kg?

Explanation

In fact, a weighing machine is a sort of spring balance which measures the weight (and not the mass) of a body. When we stand on the weighing machine, our weight (which is due to gravitational attraction of the Earth) act vertically downwards. But the buoyancy due to air on our body acts vertically upwards. As a result of this, our apparent weight (true weight-buoyancy force) is less than the true weight. since the weighing machine measure the apparent weight, our true weight is more, i.e., more than 42 kg.