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3 years ago

How much heat energy (in megajoules) is needed to convert 7 kilograms of ice at –9°C to water at 0°C?

1 answer:

8 0

The heat required to change the phase of a substance can be calculated by using the formula,

q = mCΔT where q is the heat needed, m is the mass of the substance, C is the specific heat capacity and ΔT is the change in temperature.

q = 7000 g (4.18 J/ g °C) (0°C - (-9°C))
q = 263340 J or .26334 MJ
Hope it's correct! ( If so rank as brainliest answer) :)

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You are working at a company that manufactures electri- cal wire. Gold is the most ductile of all metals: it can be stretched in

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Explanation:

We know that the relation between volume and density is as follows.

Volume = $\frac{\text{mass}}{\text{density}}$

So, V = $\frac{10^{-3}}{19.3 \times 10^{3} kg/m^{3}}$

= $5.181 \times 10^{-8} m^{3}$

Now, we will calculate the area as follows.

Area = $\frac{\text{volume}}{\text{length}}$

= $\frac{5.181 \times 10^{-8} m^{3}}{2.4 \times 10^{3}}$

= $2.15 \times 10^{-11} m^{2}$

Formula to calculate the resistance is as follows.

R = $\rho \frac{l}{A}$

= $\frac{2.44 \times 10^{-8} \times 2400}{}2.15 \times 10^{-11}}$

= $2.71 \times 10^{6} ohm$

Thus, we can conclude that the resistance of given wire is $2.71 \times 10^{6} ohm$ .

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2 years ago

A student says that since the atomic theory is just a theory, it should not be considered useful. Which statement best argues ag

yarga [219]

Theories are usually backed up with a lot of evidence. If the evidence is well studied then it is useful information.

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2 years ago

If a baseball travels a distance of 4 meters in 5 seconds, what is its average speed

Alisiya [41]

Answer:

speed=d/t.

s=4/5=0.8m/s.

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2 years ago

Elements with atomic numbers 58 through 71 are part of what series?

maria [59]

Elements with atomic numbers from 58 through 71 are part of the

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2 years ago

Read 2 more answers

The refractive index n of transparent acrylic plastic (full name Poly(methyl methacrylate)) depends on the color (wavelength) of

Novosadov [1.4K]

Answer:

The angle between the blue beam and the red beam in the acrylic block is

$\theta _d =0.19 ^o$

Explanation:

From the question we are told that

The refractive index of the transparent acrylic plastic for blue light is $n_F = 1.497$

The wavelength of the blue light is $F = 486.1 nm = 486.1 *10^{-9} \ m$

The refractive index of the transparent acrylic plastic for red light is $n_C = 1.488$

The wavelength of the red light is $C = 656.3 nm = 656.3 *10^{-9} \ m$

The incidence angle is $i = 45^o$

Generally from Snell's law the angle of refraction of the blue light in the acrylic block is mathematically represented as

$r_F = sin ^{-1}[\frac{sin(i) * n_a }{n_F} ]$

Where $n_a$ is the refractive index of air which have a value of $n_a = 1$

$r_F = sin ^{-1}[\frac{sin(45) * 1 }{ 1.497} ]$

$r_F = 28.18^o$

Generally from Snell's law the angle of refraction of the red light in the acrylic block is mathematically represented as

$r_C = sin ^{-1}[\frac{sin(i) * n_a }{n_C} ]$

Where $n_a$ is the refractive index of air which have a value of $n_a = 1$

$r_C = sin ^{-1}[\frac{sin(45) * 1 }{ 1.488} ]$

$r_F = 28.37^o$

The angle between the blue beam and the red beam in the acrylic block

$\theta _d = r_C - r_F$

substituting values

$\theta _d = 28.37 - 28.18$

$\theta _d =0.19 ^o$

4 0

2 years ago