Question

The wheels of a car are of diameter 80 cm each. How many complete revolutions does each wheel make in 10 minutes when the car is travelling at a speed of 66 km per hour?​

Answer 1

$\huge\underline\mathrm{Question}:-$

The wheels of a car are of diameter 80 cm each. How many complete revolutions does each wheel make in 10 minutes when the car is travelling at a speed of 66 km per hour?

$\huge\underline\mathrm{Solution}:-$

The radius of car’s wheel = 80/2 = 40 cm (as D = 80 cm)

So, the circumference of wheels = 2πr = 80 π cm

Now, in one revolution, the distance covered = circumference of the wheel = 80 π cm

It is given that the distance covered by the car in 1 hr = 66km

Converting km into cm we get,

Distance covered by the car in 1hr =

(66 × 105) cm

In 10 minutes, the distance covered will be = (66 × 105 × 10)/60 = 1100000 cm/s

∴ Distance covered by car = 11 × 105 cm

Now, the no. of revolutions of the wheels = (Distance covered by the car/Circumference of the wheels) = 11 × 105 /80 π = 4375.

Answer 2

A N S W E R :

• Total number of revolutions taken by each wheel in 10 minutes is 4375 when the car is travelling at a speed of 66 km per hour.

Given :

• Diameter of car of wheel = 80cm

• Time given = 10 minutes

• Speed = 66 km per hour

To find :

• Find how many revolution does each wheel make ?

Formula and concept used :

• Each wheel cover distance equal to its circumference while covering one revolution
• Circumference of wheel = 2πr
• R is diameter/2
• 1 hours = 60 minutes
• 1 km = 1000 m
• 1 m = 100 cm

Solution :

• The wheel of car diameter = 80 cm

• Radius of wheel Diameter/2, 80/2 = 40 cm

=> Circumference of circle = 2πr

=> 2 × 22/7 × 40

=> 80 × 22/7

Now, we have,

• Find the number of revolution taken by each wheel in 10 minutes

As we know that,

• 1 hours = 60 minutes

So,

• 10 minutes = 1/6 hours

Now,

• Distance = Speed × Time

Given that,

=> Car is travelling at a speed of 66 km per hour

=> 66 × 1/6

=> 11 km

Therefore,

• Distance covered by car in 10 minutes is 11 km

Again, Also we have known that,

=> 1 km = 1000 m

=> 1 m = 100 cm

=> 1 km = 100000 cm (1000 × 100)

Therefore,

• 11 km = 1100000 cm

• Distance covered by car is 1100000 cm.

Now,

• Number of revolutions = Distance covered by car/circumference of car

=> 1100000/(80 × 22/7)

=> (1100000 × 7)/(80 × 22)

=> 4375

Hence,

• Total number of revolutions taken by each wheel in 10 minutes is 4375 when the car is travelling at a speed of 66 km per hour.