law of diminishing returns

Question 1

what is the law of diminishing returns and the short run

Answer 1

law of diminishing returns: in the short run when variable factors of production are added to a stock of fixed factors of production, total/marginal product will rise then fall
short run: at least one fixed factor of production

Question 2

why does the law of diminishing returns happen

Answer 2

initially: labour productivity rises due to specialisation and under utilisation of factors of production
then: labour productivity falls as the fixed factors of production are used up