The wheel of a car has 210 cm diameter. How many revolutions per minute must the wheel make so that the speed of the car is kept at 120 km/h ?
Answer & explanation
Correct answer: option 3
120 km/h = 120 × \(\frac{5 }{18}\) m/sec = \(\frac{100 }{3}\) m/sec
Number of revolution = \(\frac{Speed × 60 }{ π × Diameter}\)
= \(\frac{100 × 60 × 7 }{3× 22 × 2.1}\)
= 303.03