A uniform meter rule QR is balanced on a knife edge which is 55cm from R, when a mass of 10g is hung at P as shown above, the mass of the meter rule is
Attached Figure / Diagram
A
550g
B
350g
C
70g
D
35g
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Taking a moment about the support.
m(55 - 50) = 10(90 - 55)
5 m = 10 x 35
5 m = 350
m = \(\frac{350}{5}\) = 70g
Source: Myschool Past Questions Archive (Record #41657)