Four students describe the relationship between velocity and centripetal force for an object in uniform circular motion:
P: The velocity vector at any point is directed towards the centre.
Q: The velocity and centripetal force vectors are perpendicular to each other at every instant.
R: If the object is at the eastern-most point, the centripetal force acts westwards.
S: If the object is at the northern-most point, the velocity vector is directed eastwards.
Which option correctly lists all the statements that are true?
a) P and Q only
b) Q, R and S only
c) Q and R only
d) P and R only