A wheel of radius 1.4 m of car makes 70 revolution in 1 min. What is the speed of the car?

36.96

Radius of the wheel = 1.4 m

Time taken 70 revolution in 1 min

Distance covered in 1 revolution = circumference of wheel

circumference of wheel = 2πr

Speed = Distance/Time

1 min = (1/60) hr.

1 km = 1000 meter

According to the question:

Distance covered in 70 revolution = 2πr × 70

⇒ 2 × (22/7) × 1.4 × 70 

⇒ 2 × (22/7) × (14/10) × 70 = 616 metre = 0.616 km

Now, Speed = 0.616/(1/60) = 36.96 km/hr