Question

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

• A. $7.92\, km$
• B. $7.70\, km$
• C. $7.80\, km$
• D. $7.85\, km$

Answer 1

Answer: (A)

Radius of the wheel $= 35 \,cm$
$\therefore $ Circumference of the wheel $=2\pi\times35\,cm=220\,cm$.
Hence, the linear distance travelled by a point of the rim in one revolution $= 220\, cm$.
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 $= 220 \times 3600 = 792000\, cm = 7.92\, km$.