Question

the driving wheel of a locomotive engine is 2.1 m in radius.find the distance covered when it has made 8000 revolutions

Answer 1

Given that radius is 2.1m

Circumference=2πr=13.2m

Distance covered in 8000 revolutions =13.2x8000=

10500m=10.5 km

Answer 2

distance covered for 1 revolution = circumference of the wheel
                                                     = 2 x pi x r
                                                     = 2 x 22/7 x 2.1 m
                                                     = 13.2 m
so distance covered for 8000 revolution 
                                                    = 8000 x 13.2 m 
                                                    = 105600 m