Question

Explain the statement - The sparks produced during sharpening of a knife againnst a grinding wheel leave thr rim of the wheel tangentially.

Answer 1

Grinding is a process which the pieces of metal from the edge of the knife to fall out and due to high temperatures on account of friction between the two surfaces the small pieces heat and up and start to glow, producing sparks. Now, the direction of motion of an object (or direction of its velocity) moving in a circular motion is always tangential to the circle (perpendicular to radius). So, the sparks fly off the metal and will be propelled tangentially.