Question

The diameter of the wheel of a car is 56 cm. Calculate : The speed of the car, in km per hour, if its wheel makes 75 revolutions in 1 minute​

Answer 1

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Diameter of the wheel = 56 cm.

• Radius of the wheel = Diameter/2 = 56/2 = 28 cm.

Circumfrence of the wheel = 2πr

2×22/7 × 28

= 2×22×4

= 8×22

= 1.76 cm.

Given that,  = 1.76 m

• Number of revolutions in 1 minute  = 75

• Distance covered = 75×1.76 = 1.392 km.

• Distance covered in 60 minute = 1.392×60 = 83.52 km/h

Answer 2

Answer:

• 7.92 Km/h is the speed of the car.

Step-by-step explanation:

Given :

Diameter of a car wheel = 56 cm

Number of revolutions in 1 minute = 75

To find :

Speed of the car in Km/h.

Solution :

• Distance traveled by the wheel in one revolution = Circumference of the wheel.

Circumference: [2πr]

⇒ 2 × 22/7 × 56/2

⇒ 44/7 × 28

⇒ 176 cm

Distance travelled in 75 revolutions:

⇒ 176 cm × 75

⇒ 13200 cm

⇒ 13200/100 m

⇒ 132 m

Speed = Distance/Time taken:

⇒ Speed = 132/60

⇒ Speed = 2.2 m/s

or,

⇒ 2.2 × 18/5

⇒ Speed = 7.92 Km/h

∴ The speed of the car is 7.92 Km/h.