Question

The radius of a circular wheel is 1.75 m. How many revolutions will it make in travelling 11 km?

(a) 10
(b) 100
(c) 1000
(d) 10000

Answer 1

(c) 1000

Radius of the wheel = 1.75 m
Circumference of the wheel = $2\mathrm{\pi r}$
= $\left(2\times \frac{22}{7}\times 1.75\right)$cm = (2 × 22 × 0.25) m = 11 m

Distance covered by the wheel in 1 revolution is 11 m.
Now, 11 m is covered by the car in 1 revolution.
(11 × 1000) m will be covered by the car in $\left(1\times \frac{1}{11}\times 11\times 1000\right)$ revolutions, i.e. 1000 revolutions.
∴ Required number of revolutions = 1000