Step-by-step explanation:
The coin roll revolution = 4 rev / sec
Angle = 180° which is 1/2 of a revolution(360°).
The circumference of a circle is 2πr.
Radius of the circle, r = 10 mm
The circumference of this coin = 20π mm.
Again 180° is half of a roll,
the circumference = [tex]\frac{20\pi }{2}[/tex] = 10π
The coin travels 31.42 mm.