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3 years ago

Which of the following is the dot product of u = 4i + 6j – 5k and v=-10i – 8j + 10k?

Physics

1 answer:

SVETLANKA909090 [29]3 years ago

7 0

Answer:

$\vec u\ . \ \vec v=-138$

Explanation:

<u>Dot Product of Vectors </u>

The dot product of two vectors is also known as scalar product. Given the vectors

$\vec u=4\hat i+6\hat j-5\hat k$

$\vec v=-10\hat i-8\hat j+10\hat k$

The dot product is the sum of the products of each component separately

$\vec u\ . \ \vec v=(4)(-10)+(6)(-8)+(-5)(10)$

$\vec u\ . \ \vec v=-40-48-50=-138$

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What is the wavelength (in nm) of a photon emitted during transition from the n = 3 state to the n = 1 state in the H atom?

Mkey [24]

Answer:

$\lambda=103\ nm$

Explanation:

$E_n=-2.179\times 10^{-18}\times \frac{1}{n^2}\ Joules$

For transitions:

$Energy\ Difference,\ \Delta E= E_f-E_i =-2.179\times 10^{-18}(\frac{1}{n_f^2}-\frac{1}{n_i^2})\ J=2.179\times 10^{-18}(\frac{1}{n_i^2} - \dfrac{1}{n_f^2})\ J$

$\Delta E=2.179\times 10^{-18}(\frac{1}{n_i^2} - \dfrac{1}{n_f^2})\ J$

Also, $\Delta E=\frac {h\times c}{\lambda}$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

So,

$\frac {h\times c}{\lambda}=2.179\times 10^{-18}(|\frac{1}{n_i^2} - \dfrac{1}{n_f^2}|)\ J$

$\lambda=\frac {6.626\times 10^{-34}\times 3\times 10^8}{{2.179\times 10^{-18}}\times (|\frac{1}{n_i^2} - \dfrac{1}{n_f^2}|)}\ m$

So,

$\lambda=\frac {6.626\times 10^{-34}\times 3\times 10^8}{{2.179\times 10^{-18}}\times (|\frac{1}{n_i^2} - \dfrac{1}{n_f^2}|)}\ m$

Given, $n_i=3\ and\ n_f=1$

$\lambda=\frac{6.626\times 10^{-34}\times 3\times 10^8}{{2.179\times 10^{-18}}\times |(\frac{1}{3^2} - \dfrac{1}{1^2})}|\ m$

$\lambda=\frac{10^{-26}\times \:19.878}{10^{-18}\times \:2.179|\left(\frac{1}{9}-\frac{1}{1}\right)|}\ m$

$\lambda=1.03\times 10^{-7}\ m$

1 m = 10⁻⁹ nm

$\lambda=103\ nm$

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3 years ago

Which wave has a longer period and how many times, the wave with a frequency of 7000Hz or the wave with a frequency of 21.000Hz?

Nuetrik [128]

Answer:

I would say the answer is the wave of 21.000Hz

Explanation:

Because it has more frequency, and as more frequency you add, the time or longer period also increases.

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3 years ago

Technician A says when diagnosing an overheating hydraulic system, be sure that the oil cooler is not plugged and the cooler’s f

mel-nik [20]

Answer:

Tech B is correct and Tech A is incorrect.

Explanation:

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3 years ago

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Explanation:

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3 years ago

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A student obtained a clean dry glass-stoppered flask. she weighed the flask and stopper on an analytical balance and found the t

svetoff [14.1K]

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So we now know we have 29.134 g of water. To calculate the volume of the flask, simply divide by the density of the water, giving:29.134 g / (0.9973 g/cm3) = 29.213 cm3

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4 years ago