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3 years ago

A scientist designed a foam container to help keep frozen foods from melting. Which best explains how the foam works?

2 answers:

6 0

I think the answer should be D.<span>It reduces the amount of thermal energy that is transferred from outside to inside the container. </span>

Ganezh [65]3 years ago

3 0

Answer:

Explanation:

i got it on my test

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Which of the following courses might a mechanical engineer take in college?

timofeeve [1]

The course to be likely taken by a mechanical engineer in college is agriculture operations (option A).

<h3>What is engineering?</h3>

Engineering is application of mathematics and the physical sciences to the needs of humanity and the development of technology.

Mechanical engineering is a subfield of engineering concerned with designing and building machines and mechanical systems.

A mechanical engineer is an individual who specialises in the field of mechanical engineering. This means that a mechanical engineer is expected to be vast in the knowledge of designing and building machines for operations in other fields.

One of those fields that a mechanical engineer can build or design machine for is agriculture. Therefore, agriculture operations is the most likely course to be taken by a mechanical engineer in college.

Learn more about mechanical engineering at: brainly.com/question/20434227

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1 year ago

In Hooke's law, what does k represent?

kicyunya [14]

For Plato, K represents the stiffness of the spring. Hope this helps!

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3 years ago

Read 2 more answers

How are traits influenced by the environment? (No links)

Ganezh [65]

Answer:

Environmental factors influence traits in plants and animals. These traits include things like weight, height, size, and color. If a dog does not get proper nutrition and exercise, their weight will be negatively impacted. The dog is likely to be overweight if the environmental factors are not changed.

Explanation:

8 0

3 years ago

The wires in a household lamp cord are typically 3.5 mm apart center to center and carry equal currents in opposite directions.

zhuklara [117]

Explanation:

It is given that,

Distance between wires, d = 3.5 mm = 0.0035 m

Power of light bulb, P = 100 W

Potential difference, V = 120 V

(a) We need to find the force per unit length each wire of the cord exert on the other. It is given by :

$\dfrac{F}{l}=\dfrac{\mu_o I^2}{2\pi r}$

Power, P = V × I

$I=\dfrac{P}{V}=\dfrac{100}{120}=0.83\ A$

This gives, $\dfrac{F}{l}=\dfrac{4\pi \times 10^{-7}\times (0.83)^2}{2\pi \times 0.0035}$

$\dfrac{F}{l}=0.0000393\ N/m$

$\dfrac{F}{l}=3.93\times 10^{-5}\ N/m$

(b) Since, the two wires carry equal currents in opposite directions. So, teh force is repulsive.

(c) This force is negligible.

Hence, this is the required solution.

8 0

3 years ago

Piano tuners tune pianos by listening to the beats between the harmonics of two different strings. When properly tuned, the note

Sophie [7]

(a) 2 Hz

The frequency of the nth-harmonic is given by

$f_n = n f_1$

where

$f_1$ is the fundamental frequency

Therefore, the frequency of the third harmonic of the A ( $f_1 = 440 Hz$ ) is

$f_3 = 3 \cdot f_1 = 3 \cdot 440 Hz =1320 Hz$

while the frequency of the second harmonic of the E ( $f_1 = 659 Hz$ ) is

$f_2 = 2 \cdot f_1 = 2 \cdot 659 Hz =1318 Hz$

So the frequency difference is

$\Delta f = 1320 Hz - 1318 Hz = 2 Hz$

(b) 2 Hz

The beat frequency between two harmonics of different frequencies f, f' is given by

$f_B = |f'-f|$

In this case, when the strings are properly tuned, we have

- Frequency of the 3rd harmonic of A-note: 1320 Hz

- Frequency of the 2nd harmonic of E-note: 1318 Hz

So, the beat frequency should be (if the strings are properly tuned)

$f_B = |1320 Hz - 1318 Hz|=2 Hz$

(c) 1324 Hz

The fundamental frequency on a string is proportional to the square root of the tension in the string:

$f_1 \propto \sqrt{T}$

this means that by tightening the string (increasing the tension), will increase the fundamental frequency also*, and therefore will increase also the frequency of the 2nd harmonic.

In this situation, the beat frequency is 4 Hz (four beats per second):

$f_B = 4 Hz$

And since the beat frequency is equal to the absolute value of the difference between the 3rd harmonic of the A-note and the 2nd harmonic of the E-note,

$f_B = |f_3-f_2|$

and $f_3 = 1320 Hz$ , we have two possible solutions for $f_2$ :

$f_2 = f_3 - f_B = 1320 Hz - 4 Hz = 1316 Hz\\f_2 = f_3 + f_B = 1320 Hz + 4 Hz = 1324 Hz$

However, we said that increasing the tension will increase also the frequency of the harmonics (*), therefore the correct frequency in this case will be

1324 Hz

8 0

3 years ago