Question

The diameter of each wheel of a car is 70 cm. If each wheel rotates 400 times per minute, then the speed of the car (in km/hr) is (Take π = 22/7):​

Answer 1

Answer:

If each wheel rotates 400 times per minute, then the speed of the car (in km/hr) is. 0.528.

Step-by-step explanation:

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Answer 2

Diameter = 70 cm

Circumference = 2πr

= 2 × 22/7 × 70/2

= 220 cm

Therefore,

In one rotation , the wheel covers = 220 cm

= 220/100000

= 0.0022 km

Now,

Time taken to rotate 400 times = 1 min

Time taken to rotate 1 time = 1/400 mins

= 1/400 ÷ 60

= 1/400 × 1/60

= 1/24000 hour

Hence, speed of car =

distance travelled in one rotation ÷ time taken in one rotation

= 0.0022 ÷ 1/24000

= 0.0022 × 24000/1

= 2.2 × 24

= 52.8 km/hr Ans.