What is the maximum force a hammer can apply to a steel nail 2.5 mm in diameter of the nails elastic limit is not to be exceeded

Yield strength of mild steel is given as

here we know that

now we can rearrange it as

here we know that

so maximum applied force will be F = 1.23 * 10^3 N

what type of charge does it have? negative

a lot of it means it can be "burned" for energy and sold at one price. if it is scarce, the price will go up