Copper has a breaking stress of about

3 × 10^8 N/m2.

What is the maximum load that can be
hung from a copper wire of diameter 0.5 mm?
Answer in units of N.

If 55% of this maximum load is hung from the copper wire, by what percentage of its length will it stretch?
Answer in units of %.

I got the first one which is 58.90486N. I have no idea how to do the second though.

1 answer

Force=E*a*deltaL/L

solve for delta L/L
E is Youngs modullus for Copper, look that up