Question

A wheel rotates making $20$ revolutions per second. If the radius of the wheel is $35cm$, what linear distance does a point of its rim travel in three minutes? (Take $\pi =\frac{22}{7})$

• A. 7.92 km
• B. 7.70 km
• C. 7.80 km
• D. 7.85 km

Answer 1

Answer: (A)

Radius of the wheel $=35cm$
$\therefore$ Circumference of the wheel $=2\pi \times 35cm$
$=2\times \frac{22}{7}\times 35cm=220cm$
Hence, the linear distance travelled by a point of the rim in one revolution $=220cm$. Number of revolutions made by the wheel in 3 minutes $=20\times 3\times 60=3600$
$\therefore$ The linear distance travelled by a point of the rim in $3$ minutes $=220\times 3600=792000cm=7.92,km.$