Which force is responsible for the separation of cream from churned milk?

Correct answer: (b) Centrifugal force

Explanation

In a cream separator, milk is spun very fast. In the rotating frame, every particle feels an outward centrifugal force that grows with its mass:

• the heavier skimmed milk is thrown outwards, towards the wall;
• the lighter cream (fat) collects near the centre and is drawn off.

The same principle is used in washing-machine driers and in laboratory centrifuges that separate blood cells from plasma.