Accounting doubt for capital

Fixed capital= Investments in FD's, securities, shares etc

Working capital = current cash requirements to meet the cash operating cycle. 

Circulating cash= can be cash in hand or petty cash or small loans and advances given to others. 

To make your understanding better, working capital is vast

You have to find out Net working capital using the percentage of sales method to budget how much cash you need for operations.

You have factoring facility to reduce receivable days

Your formula is like current assets - current liabilities which will give current balance

Working capital bank loans have different methods to get a loan like tandon method, turnover method or permissable method Etc for funding

Cash can be managed by investing in securities using EOQ / Baumols cash model where they sell securities to meet the cash levels.

Forgot there is miller orr method of cash management

Cash budget to get working capital bank loans.

Technically Capital= assets- liabilities, however, Fd is like investment capital.