The diagram shows a uniform meter rule AB which balances horizontally at the 90cm mark when a mass of 0.2kg is suspended from B. Calculate the mass of the meter rule.

A. 0.05kg
B. 0.20kg
C. 0.80kg
D. 1.00kg

Correct Answer: Option A

A. 0.05kg

Explanation

Mr (90 – 50) = 0.2(100 – 90)
40Mr = 0.2 × 10

Mr = 2
40 = 0.05kg