Question

The diameter of a wheel of a car is 84 cm. How many revolutions will it make to travel 64 km

Answer 1

Answer:

Let r be the radius of the wheel. Then,

Diameter = 84 cm

2r=84

r=42 cm

Circumference of the wheel = 2πr=264cm=2.64m

So, the wheel covers 2.64 meters in one complete revolution.

Total number of revolutions in covering 792 meters = 792/2.64 =300.

Hence, the wheel takes 300 revolutions in covering 792 meters.

Answer 2

The diameter of a wheel of a car is 84 cm. revolutions to complete 64 kilometres.

Given

Diameter of circle =84 cm

The radius of circle =

$\frac{diameter}{2}$

So the radius of circle =84/2

=42cm

=0.42meter.

Circumference of circle

$2\pi \times r$

Circumference of given circle = 2π×0.42 m

$2 \times \frac{22}{7} \times 0.42 = 2.64m$

Given distance = 64km

=64000 meters

No Of revolution=

$\frac{distance}{circumference} = \frac{64000}{2.64} =24242.42$

So the circle have to make 24,242.42 revolution to complete 64 kilometres