2016 · Q52
There are two concentric circles. The radii of the two circles are 100 m and 110 m respectively. A wheel of radius 30 cm rolls on the smaller circle and another wheel rolls on the larger circle. After they have completed one revolution, it is found that the two wheels rolled equal number of times on their respective axes. What is the radius of the other wheel?
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- A31 cm
- B32 cm
- C33 cm
- D34 cm
Explanation
The 30 cm wheel rolling on the 100 m circle rotates (2 pi x 100)/(2 pi x 0.3) = 100/0.3 times. The other wheel of radius R on the 110 m circle rotates 110/R times. Equating the two counts: 110/R = 100/0.3, giving R = 0.33 m = 33 cm. Hence the other wheel's radius is 33 cm.