From the figure, a uniform metre rule of weight 20 N is in equilibrium. A string is attached at the 0 cm mark, and a pivot is placed 30 cm from the 0 cm end (70 cm from the other end). Calculate the tension T in the string.
Attached Figure / Diagram
A
5 N
B
15.4 N
C
11.5 N
D
25.3 N
Verified Correct Answer: A.
Step-by-Step Mathematical Solution
From the diagram
Clockwise moment (weight) = 20 × 0.20 = 4 N·m
Anticlockwise moment (tension) = T × 0.70
T × 0.70 = 4 ⇒ T ≈ 5.7 N
Source: WAEC / JAMB / NECO Classroom Archive (Record #78259)