Hi.my questions are.
1-Are the instantaneous velocity vector and the acceleration vector always in the direction of the motion? Why?

2-is it possible for the velocity vector of a particle to be perpendicular to its position vector? Why?

3-is it possible for a particle to go around a curve at constant speed without expressing an acceleration.Why?
Thanks

We won't just do your homework for you. You should take a shot at answering these questions yourself - especially the "why" part - and then we'll help you along if you get stuck.