Question

why an object under uniform circular motion needed a force to act upon it continuously name the force and direction

Answer 1

Any body that undergoes UCM experiences two types of forces :-

1. Centrifugal force - outwards
2. Centripetal force - inwards

Answer 2

acceleration is a vector quantity..it can change through direction and magnitude
in circular motion there exit continous change in magnitude.
as second law of newton states F=ma
this imply accelaration is only due to force
in uniform circular body acellarion is known as cenerpetal accelaration and force is centerpetal force..which is alwas directed towards center