Q In fig,  the upper wire is made of steel  and the lower of copper. The wires have equal cross - section. Find the ratio of the longitudinal strains developed inthe two wires.

The fig shows a wire , almost half of which is steel and rest is copper. This is hanging from the celing with cu part downward. An unspecified mass is attached with the end of the wire ( cu part )

Actually this from page, 300 of hcv vol I, q 5

plz show all assumptions mathematically.

acoording to the figure iam taking the the length of entire wire as 2L

so each one has a length of L

let the tension be T and is equal for both the wires

Y (steel)= TL/ A  delta  L (steel)

Y( copper)= TL/ A delta (copper)

divide the both equations

u will get the ans as 20/13  or 1.53

1. Y is not  supplied.

2.let the tension be T and is equal for both the wires-----------why ? there r 2 wires and both have a certain mass.

no yaar, something is missing our mind.!!!!

I don't know. But something.

Can it be done with FBD assuming length of wire to be same ?

no . I m not satisfied.

1. I consider the strings have some mass ---at least they should have

2. Y is not supplied unlike Q no 4

3. the lower mass , say m

Then how will be the FBD ? Or, is it the correct approach?

I can give u the strain developed in the wire due its own wt and a load at the end , Do u need that ?

Surely u r joking Mr. Feynman .

I want both lemon and cream.

Both strai developed and soln. he he he !!