Can you open this?
Because of the anatomy of the muscles of our hands and arms it is not possible to tighten the lid of a jar beyond the point where you can still remove it – when using your right hand. With our right hands we are able to produce a greater twisting force in a clockwise direction than anticlockwise. As such, if using your right hand, and assuming the conditions when you go to open a jar are the same as when you closed it, you will be able to apply a greater torque when removing the lid. Using your left hand, however, it is theoretically possible to tighten the lid of a jar beyond the point where you could remove it yourself with the same hand.