Jackknifing refers to the folding of an articulated vehicle so that it resembles the acute angle of a folding pocket knife. If a vehicle towing a trailer skids, the trailer can push the towing vehicle from behind until it spins the vehicle around and faces backwards.

What are jack knives for?

Jack knife sit ups are a great low-impact exercise for strengthening abdominal muscles. They are a great way to tighten the lower abs and help you get six pack abs. Jack knife sit ups will give your abs challenging workout, but the basics are easy to master!

What kind of knife is a jack knife?

Pocket knife or jackknife, a compact, foldable knife.