Question

A
square metal bar of 25mm side, 0.38mm long and mass 0.8 kg is
suspended by a wire of 0.4 mm long and 0.5 mm radius. It is observed
to make 50 oscillations in 335.7 seconds. Calculate the Rigidity Modulus
of the material of the wire.
(Ans.34.5 GPa)​

Answer 1

Answer:

I'm not sure what you mean by "4.87m long wire" in this case. If it's the length in the state of being loaded with 2 kg or in the state without any loading. So here are 2 answers:

1) if bar is 4,87 m long when subjected to 2 kg load (so it's already deformed):

elongation under one more kg is equal to 2,08 mm

2) if bar is 4,87 m long when there is no loading:

a total load of 3 kg will cause elonagtion equal to 6,24 mm

Anyway - formula for elongation: ΔL=F*L/E*A