A particle is moving on a circular path with constant speed, then its acceleration will be:
A. zero
B. external radial acceleration
C. internal radial acceleration
D. constant acceleration

Hint: In order to solve this question, we will use the concept of circular motion and acting acceleration and forces on the body moving in circular motion and then we will determine the correct option regarding acceleration for a body moving in a circular path.

Complete step by step solution:
A circular motion is one when a body moves in circular path having definite radius and here we have given that a particle is moving on a circular path with constant speed and now as we know that acceleration is a vector quantity it has magnitude and direction as well and since velocity at each point on the circumference of the body changes at the magnitude remain constant but direction changes at each point so the acceleration changes though its direction. Hence, option (A) and (D) are incorrect.

Now, when a body moves in a circular path it experiences a force which keeps it in circular path called centripetal force and force is directed radially towards the centre of the circular path inwardly therefore the acceleration is also internal radial acceleration because this internal acceleration is which keeps the body in circular motion.

Hence, the correct answer is option C.

Note: It should be noted that, mathematically the magnitude of the centripetal acceleration which acts inwardly radially is calculated using the formula $a = \dfrac{{{v^2}}}{r}$ where v is the velocity and r is the radius of the circular path in which body is moving.