Question 75

The diameter of a cycle wheel is 70 cm. A cyclist takes 30 hours to reach a destination at the speed of 22 km/hr. How many revolutions will the wheel make during this journey?

Solution

Distance covered at 22 km/hr in 30 hours = $$22\times30=660$$ km = $$66\times10^6$$ cm

Radius of cycle = 35 cm

In one revolution, distance covered by the wheel = Circumference of cycle = $$2\pi r$$

= $$2\times\frac{22}{7}\times35=220$$ cm

$$\therefore$$ Number of revolutions in the total journey = $$\frac{66\times10^6}{220}=3\times10^5$$

= 3 lakh revolutions

=> Ans - (B)

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