A 200 g mass is placed on the meter stick 20 cm from the fulcrum. An unknown mass is positioned 8 cm from the fulcrum to balance the system. What is the mass of this unknown object?​

Which statement best describes the superposition principle? a.) if two in-phase waves arrive simultaneously at a point, their amplitudes add up b.) if two out-of-phase waves arrive simultaneously at a point, their amplitudes add up c.) if two in-phase waves arrive at a point one after another, their amplitudes add up d.) if two out-of-phase waves arrive at a point one after another, their amplitudes adds up