The figure shows a uniform metre rule of weight 100 N balanced by a knife edge at the 10 cm mark and a cord attached at the 85 cm mark. What is the tension in the string?
Attached Figure / Diagram
A
23.62 N
B
53.33 N
C
35.74 N
D
78.68 N
Verified Correct Answer: B.
Step-by-Step Mathematical Solution
Answer: B
For equilibrium, clockwise moment = anticlockwise moment about the pivot.
clockwise distance from pivot: 50cm - 10cm = 40cm
anticlockwise distance from pivot: 85cm - 10cm = 75cm
Applying the principle of moments
W x distance(w) = T x distance(T)
100 x 40 = T x 75
T = \(\frac{ 4000}{75}\) ≈ 53.33N
Source: WAEC / JAMB / NECO Classroom Archive (Record #74377)