There are two coins; one of radius r1 and the other of radius r2. The r1 coin is made to rotate around the circumference of r2. What is the number of rotations r1 will make around its own axis?

Ops: A. r2/r1
B. (r1+r2)/r1
C. (r2-r1)/r1
D. 2 * r2/r1

• a. r2/r1
  Let
  radius of smaller circle = r1 and
  radius of bigger one = r2
  revolutions = 1
  
  then n*2*pi*r1 = 2*pi *r2 i.e n = r2/r1
• 11 years agoHelpfull: Yes(2) No(0)