3 question ple answer

The world’s supply of fossil fuels will _____.

Mekhanik [1.2K]

The world’s supply of fossil fuels will dwindle slowly until a replacement source is found that provides the same power.

bc some day we will actually run out of it and find sth that gives power

3 0

3 years ago

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The latent heat of vaporization for water at room temperature is 2430 J/g.

alukav5142 [94]

Answer:

1) $kinectic energy=7.26*10^-^2^0J$

2) $V= 2.0m/s$

3) $T=3.5*10^3K$

4) The Molecules do not burn because of the presences of hydrogen bond in place

Explanation:

From the question we are told that

latent heat of vaporization for water at room temperature is 2430 J/g.

1)Generally in determining the molar mass of water evaporated we have that

-One mole (6.02 x 10. 23 molecules)

-Molar mass of water is 18.02 g/mol

Mathematically the mass of water is give as

$M=\frac{18.02}{6.02*10^-^2^6}$

$M=3*10^-^2^3g$

Therefore

$kinectic energy=2430J/g*3*10^-^2^3g$

$kinectic energy=7.26*10^-^2^0J$

b)Generally the evaporation speed V is given as $V= \sqrt{\frac{K.E*2}{m} }$

Mathematically derived from the equation

$\frac{1}{2} mv^2 =K.E$

To Give

$V= \sqrt{\frac{K.E*2}{m} }$

$V= \sqrt{\frac{7.26*10^-^2^0J*2}{3*10^-^2^3g} }$

$V= 2.0m/s$

c)Generally the equation for velocity $Vrms=\sqrt{\frac{3RT}{M} }$

Therefore

Effective temperature T is given by

$T=\frac{\sqrt{v}*m}{R}$

where

$T=\frac{\sqrt{2.0m/s}*6.02*10^-^2^6}{0.082057 L atm mol-1K-1}$

$T=3.5*10^3K$

4) The Molecules do not burn because of the presences of hydrogen bond in place

3 0

3 years ago

Which of the following is the reason a lever is used in a shovel?

storchak [24]

The figure shown below illustrates a lever being used to lift a weight W.
The applied force is F.

In order to lift the weight, the minimum applied force is
F*b = W*a
F = (a/b)W

When the ratio a/b < 1, then the applied force is less than the weight.
The principle behind the use of a lever is to keep the ratio a/b small in order to decrease the effort force.

Answer: A
A lever is used to decrease effort force.