Area and Perimeter Practice Test 2

Question : 31 of 40

Marks: +1, -0

Wheels of diameters 7 cm and 14 cm start rolling simultaneously from X and Y, which are 1980 cm apart, towards each other in opposite directions. Both of them make the same number of revolutions per second. If both of them meet after 10 seconds, find the speed of smaller wheel.

88 cm/sec
66 cm/sec
55 cm/sec
44 cm/sec

Validate

Solution:

Let the wheels make n revolutions per second, then

({22}/7×7 + {22}/7 ×14) × 10n

= 1980
⇒ 66n = 198
∴ n = 3
Since, distance travelled by smaller wheel in 1 second =

{22}/7 × 7× 3

= 66 cm
Hence, speed of the smaller wheel = 66 cm/sec.

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