Question 14
A circular coin $A$ rolls without sliding along the circumference of a stationary circular coin $B$, whose radius is twice that of $A$. Let $x$ be the number of degrees through which coin $A$ rotates about its own centre until it first returns to its initial position. Find $x$.
Interpretation: the coins roll in external contact, and “first returns to its initial position” means the moving coin’s centre completes its first full orbit.
Interpretation: the coins roll in external contact, and “first returns to its initial position” means the moving coin’s centre completes its first full orbit.