Question

The wheel of a motorcycle is of radius 35 cm. How many revolutions per minute must the wheel make so as to keep a speed of 66 km/hr ? 

Answer 1

Given, radius of wheel, r = 35 cm

Circumference of the wheel

= 2πr

= `2 xx 22/7 xx 35  "cm"`

= 220 cm

But speed of the wheel

= 66 km/h^–1

= `(66 xx 1000)/60` m/min

= 1100 × 100 cm/min^–1

= 110000 cm/min^–1

∴ Number of revolutions in 1 min

= `(110000)/220`

= 500 revolutions

Hence, the required number of revolutions per minute is 500.