vertical circular motion

hi! this might be a really silly question but im revising for a level aqa further maths and was wondering something about vertical circular motion -

when we talk about something moving in complete circles (ie not falling off before reaching the top) it seems like some questions want me to say that the tension/reaction force is greater than zero when this happens and others want me to say that the speed is greater than zero - as far as i understand these arent the same thing, so could someone please clarify this? thanks!!

Depends on the question and how the particle is constrained to move. To complete a full circle, or "go over the top":

If the particle is attached to the centre of motion solely via a string (i.e. it can go slack), then you'd need the tension to be non-negative at the top of the motion (this would imply positive everywhere else also).

If the particle is attached via a rod (can't go slack), or on a smooth wire, then negative tension is possible, and you'd require the speed to be greater than zero at the top of the motion.