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3 years ago

Please explain how to do this

Mathematics

1 answer:

user100 [1]3 years ago

7 0

Answer:

Option 4

Step-by-step explanation:

Area of a circle (A) = πr²-------------(i)

Circumference (C) = 2πr

=>C = 2πr

=> 2πr= C

=> π = C/2r

Substituting the value of π = C/2r in the first equation i.e (i)

A = (C×r²)/2r

= (C . r)/2

= 1/2 × C × r

Therefore, option 4 is the correct option

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If 2.5 mol of dust particles were laid end to end along the equator, how many times would they encircle the planet? The circumfe

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Answer:

They encircle the planet $3.76\times 10^{11}$ times.

Step-by-step explanation:

Consider the provided information.

We have 2.5 mole of dust particles and the Avogadro's number is $6.022\times 10^{23}$

Thus, the number of dust particles is:

$2.5\times 6.022\times 10^{23}=15.055\times 10^{23}$

Diameter of a dust particles is 10μm and the circumference of earth is 40,076 km.

Convert the measurement in meters.

Diameter: $10\mu m\times \frac{10^{-6}m}{\mu m} =10^{-5}m$

If we line up the particles the distance they could cover is:

$15.055\times 10^{23}\times 10^{-5}=15.055\times 10^{18}=1.5055\times 10^{19}$

Circumference in meters:

$40,076km\times \frac{1000m}{1km}=40,076,000 m$

Therefore,

$\frac{1.5055\times 10^{19}}{40,076,000} = 3.76\times 10^{11}$

Hence, they encircle the planet $3.76\times 10^{11}$ times.

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Mumz [18]

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<=>

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