A uniform meter rule is balanced at 30cm mark when a mass of 50g is hanging from its zero mark. calculate the weight of the rule.

3 answers

moments about zero point, m down at middle, m+50 up at 30
m * 50 cm = (m +50) * 30
(50-30) m = 1500
20 m = 1500
m = 75 grams
----------------------------------
Now, I do not know if you are in a physics class that uses SCI units. If so
then weight is m g in NEWTONS where m is in Kilograms and g is about 9.81 meters/ second^2
if so
weight = 0.075 kg * 9.81 m/s^2 = 0.736 Newtons
The answer is correct
70N