When moving in gear car makes a sharp grinding noise like knifes being sharpened - so frightening

This means that you need to replace your front brake pads. There are two metal bars on the brake pads that rub against the rotor when they get worn down to a certain point, causeing that "nails on a chalkboard" sound whenever the car moves. It's just a safety indicator that most car manufacturers use, as the horrid sound is hard to ignore, and people would rather get it fixed right away than endure it any longer. Hope this is what you were after.