How did enslaved Africans most contribute to the growth of the northern economy during the first half of the nineteenth century?

they worked to produce goods that were sold and traded which resulted in a boom in trade with the north as the north needed things the south had but it was the slaves making the things the south had.

ok, so basically your gonna start with 350 ok. so there's 60 seconds in a minute so that means you he can go up 10 ft per minute. soo, after 3 minutes he should be at 260 ft after three minutes : )