A uniform half meter rule is pivoted at it's 30cm .amass of 50g . Hung at the 45cm mark keeps the rule horizontal . Determine the mass of the half meter rule.

Answer 1

Let x be the mass of the half meter rule.

Since the rule is in equilibrium, the sum of the moments about the pivot point must be zero.

Taking moments about the pivot point:
(50g)(15cm) = x(30cm)
750 g cm = 30x cm
x = 25 g

Therefore, the mass of the half meter rule is 25g.