A woman is riding a bicycle whose wheels are 700mm in diameter. If the wheels rotate at 100 revolutions per minute (rpm), find the speed (in km/h) at which she is traveling.
distance covered by one rotation = 2π(35) cm , (1 cm = 10 mm)
= 70π cm
so in 1 minute the bike goes 100(70π) cm
speed
= 70π m/(1/60 hrs) , (1 m = 100 cm)
= 4200π m/hr
= 4.2π km/h , (1 km = 1000 m)
= appr 13.2 km/h