Question

The diameter of the driving wheel of a bus is 140 cm how many Revolution per minute must the wheel make in order to keep a speed of 66 km per hour

Answer 1

Q:

The diameter of the driving wheel of a bus is 140 cm. How many revolution, per minute must the wheel make in order to keep a speed of 66 kmph ?

A) 150B) 250C) 350D) 550

Answer:   B) 250 

Explanation:

Circumference = No.of revolutions * Distance covered

Distance to be covered in 1 min. = (66 X1000)/60 m = 1100 m.
Circumference of the wheel = 2 x (22/7) x 0.70 m = 4.4 m.
Number of revolutions per min. =(1100/4.4) = 250.