Question

Q.43 The radius of a wheel is 7 cm. How many revolutions will it mal
moving 44km?
1) 2000 2) 10000
3) 70000
4) 100000
ctive​

Answer 1

Answer:

answer is 4) 1000000

Step-by-step explanation:

2πr=2*22/7*7

=0.44 m

no. of revolution=distance/ circumference

=44000/0.44

=1000000

Answer 2

$\huge \rightarrowtail\mathbb{ANSWER} \leftarrowtail$

Given :-

• Radius of the wheel = 7 cm

• Distance = 44 km

Required to find :-

• No. of revolutions ?

Formula used :-

$\small{\dagger{\boxed{\mathbf{PERIMETER \ OF \ THE \ CIRCLE = 2 \pi r }}}}$

Units Conversion :-

Before solving the question we need to convert some units from one unit to another unit .

The unit which is needed to be converted is Distance

We need to convert the distance from kilometres to centimetres

we know that ;

• 1 m = 100 cm

• 1km = 1000 meters

So,

• 1 km = 1,00,000 cm

Hence,

44 km = ?

=> 44 x 1,00,000

=> 44,00,000 cm

Hence,

Distance = 44,00,000 cm

Solution :-

$Given \begin{cases} \text{Radius \: of \: the \: circle = 7 cm }\\ \text{Distance = 44,00,000 \ km}\end{cases}$

we need to find how many revolution will the wheel took to travel 44,000 meters

So,

Using the above formula ,

$\small{\dagger{\boxed{\mathbf{PERIMETER \ OF \ THE \ CIRCLE = 2 \pi r }}}}$

Here.

Let's take π = 22/7

So,

$\longrightarrow{\rm{ Perimeter = 2 \times \dfrac{22}{7} \times 7 }}$

$\longrightarrow{\rm{ Perimeter = 2 \times \dfrac{22}{ \cancel{7}} \times \cancel{7} }}$

$\longrightarrow{\rm{ Perimeter = 2 \times 22 }}$

$\longrightarrow{\rm{Perimeter = 44 }}$

Hence,

perimeter of the wheel = 44 cm

Here,

Distance travelled in 1 revolution = perimeter of the circle

So,

From this we can conclude that ;

$:\rightarrowtail{\tt{ No. \ of \ revolutions = \dfrac{ Distance }{Perimeter \ of \ the \ wheel }}}$

Hence,

$:\rightarrowtail{\tt{ No. \ of \ revolutions = \dfrac{ 44,00,000\ cm}{ 44 \ cm} }}$

$:\rightarrowtail{\tt{ No. \ of \ revolution = 1,00,000 }}$

Therefore,

No. of revolutions made by the wheel to travel 44,00,000 cm is 1,00,000 revolutions