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2 years ago

Wood, plastic, rubber and air are good insulators because

Physics

2 answers:

ruslelena [56]2 years ago

7 0

Answer: c) they don’t have free electrons.

Explanation: Wood, plastic, rubber, and air are good insulators because, obviously, they are bad conductors.

This is because the do not have a lot of free electrons, so when you apply an electric field, the total flow of electrons (or electricity) is almost zero.

In the same case, when charges try to flow into these materials (by connecting a wire to a piece of wood or something like that), there are no free electrons inside of the material, so the electrons that try to move inside the material see a lot more of obstacles against their movement.

Then the correct option is option c: they don’t have free electrons.

antiseptic1488 [7]2 years ago

6 0

Wood, plastic, rubber and air are good insulators because they don’t have free electrons.

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An internal explosion breaks an object, initially at rest, into two pieces: A and B. Piece A has 1.9 times the mass of piece B.

Helen [10]

Kinetic energy of pieces A and B are 2724 Joule and 5176 Joule respectively.

<h3>What is the relation between the masses of A and B?</h3>

Let mass of piece A = Ma

Mass of piece B = Mb

Velocities of pieces A and B are Va and Vb respectively.
As per conservation of momentum,

Ma×Va = Mb×Vb

Here, Ma=1.9Mb

So, 1.9Mb × Va = Mb×Vb

=> 1.9Va = Vb

<h3>What are the kinetic energy of piece A and B?</h3>

Expression of kinetic energy of piece A = 1/2 × Ma × Va²
Kinetic energy of piece B = 1/2 × Mb × Vb²
Total kinetic energy= 7900J

=>1/2 × Ma × Va² + 1/2 × Mb × Vb² = 7900

=> 1/2 × Ma × Va² + 1/2 × (Ma/1.9) × (1.9Va)² = 7900

=> 1/2 × Ma × Va² ×(1+1.9) = 7900 j

=> 1/2 × Ma × Va² = 7900/2.9 = 2724 Joule

Kinetic energy of piece B = 7900 - 2724 = 5176 Joule

Thus, we can conclude that the kinetic energy of piece A and B are 2724 Joule and 5176 Joule respectively.

Learn more about the kinetic energy here:

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1 year ago

Holding onto a tow rope moving parallel to a frictionless ski slope, a 70.1 kg skier is pulled up the slope, which is at an angl

lara [203]

Answer:

given,

mass of the skier = 70.1 Kg

angle with horizontal, θ = 8.6°

magnitude of the force,F = ?

a) Applying newton's second law

$m g sin\theta - F_{rope} = ma$

velocity is constant, a = 0

$m g sin\theta - F_{rope} =0$

$F_{rope} = m g sin\theta$

$F_{rope} = 70.1\times 9.8\times sin 8.6^0$

$F_{rope}= 102.73\ N$

b) now, when acceleration, a = 0.135 m/s²

$F_{rope}-m g sin\theta = ma$

velocity is constant, a = 0.135 m/s₂

$F_{rope} = m g sin\theta+ma$

$F_{rope} = 70.1\times 9.8\times sin 8.6^0+70.1\times 0.135$

$F_{rope}= 112.19\ N$

7 0

3 years ago

If a steady-state heat transfer rate of 3 kW is conducted through a section of insulating material 1.0 m2 in cross section and 2

kaheart [24]

Answer:

$\Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K$

So then the difference of temperature across the material would be $\Delta T = 375 K$

Explanation:

For this case we can use the Fourier Law of heat conduction given by the following equation:

$Q = -kA \frac{\Delta T}{\Delta x}$ (1)

Where k = thermal conductivity = 0.2 W/ mK

A= 1m^2 represent the cross sectional area

Q= 3KW represent the rate of heat transfer

$\Delta T$ is the temperature of difference that we want to find

$\Delta x=2.5 cm =0.025 m$ represent the thickness of the material

If we solve $\Delta T$ in absolute value from the equation (1) we got:

$\Delta T =\frac{Q \Delta x}{Ak}$

First we convert 3KW to W and we got:

$Q= 3 KW* \frac{1000W}{1 Kw}= 3000 W$

And we have everything to replace and we got:

$\Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K$

So then the difference of temperature across the material would be $\Delta T = 375 K$

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3 years ago

A boater is accompanied by a person at least 16 years of age. In michigan, what is the youngest age that this person can be and

dexar [7]

The youngest age that this person can be and legally operate a boat powered by a motor of more than 35 hp will be 12 years of age.

<h3 /><h3>What is electric power?</h3>

It is the rate of the electric work done. Its unit is the watt. Horsepower is the unit of power.

A person under the age of 12 may only legally operate a boat with a motor that has more than 6 horsepower but no more than 35 horsepower

if they meet two requirements: they have a boating safety certificate, which they must have on board; and they are being closely watched by an adult who is at least 16 years old.

Hence the youngest age that this person can be and legally operate a boat powered by a motor of more than 35 hp will be 12 years of age.

To learn more about electric power refer to the link;

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1 year ago

If the speed of light in a substance is 2.26 x 10^8 m/s, what is the index of refraction of that substance?

vladimir1956 [14]

Answer:

1.33

Explanation:

speed of light in vacuum, c = 3 x 10^8 m/s

speed of light in medium, v = 2.26 x 10^8 m/s

The refractive index of the medium is given by

μ = speed of light in vacuum / speed of light in medium

μ = (3 x 10^8) / (2.26 x 10^8)

μ = 1.33

4 0

2 years ago