how does capital deepening increase output per worker?

Answer 1

A simple explaination is the shovels and bull dozers. A wheel barrow and a shovel don't cost much. Minimum capital, but a man with a wheel barrow and a shovel can't move as much dirt as a man with a bulldozer. But a bulldozer cost a lot more than a shovel.

The output, moving dirt, is increased per worker by providing additional capital (bulldozer).

Answer 2

Simply put "capital" (money) spent to improve the process (what ever it may be) will let each worker make more "product", usually with less effort. More product, more sales.