Question

Due to what type of inertia, the spark leaves the grind Stone tangentially while sharpening the knife?

Answer 1

It is not any inertia.

When an object is in circular motion, the direction of the motion is always tangential.The sparks produced are also in circular motion.So when they fall, the direction is tangential

Hope This Helps You!

Answer 2

Due to circular motion, sparks get thrown tangentially.
This is due to inertia of direction.