word pairings

[rhylmark]

what word pairings are associated with following....elbow flexor and elbo extensor 2) lactose solids and lactose liquids. 3) horizontal axis and vertical axis and 4) a linear gear and a circular gear, thanks

[squarebear]

1 - biceps and triceps
2 - curds and whey
3 - x and y
4 - rack and pinion?

[rhylmark]

i am shamed by your genius ! thanks you

[squarebear]

I'm not sure about rack and pinion though. I know it's something to do with gears but apart from that I'm stumped.

[scorpioangel]

spot on with rack and pinion squarebear -
The rack and pinion is used to convert between rotary and linear motion. The rack is the flat, toothed part, the pinion is the gear

[squarebear]

Well you learn something new every day.