A uniform metre rule is balanced at the point 30cm mark when a mass of 50g is hanging from its zero cm mark. Calculate the weight of the rule.
center of rule is at 50 cm, 20 cm from bal point
20 m = 50 * 30
m = 50 * 30 / 20 GRAMS = 75 grams = 0.075 Kilograms
BUT grams is not weight, just mass
weight = m g = about 0.075 * 9.81 NEWTONS on earth