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3 years ago

The line spectrum of lithium has a red line at 670.8 nm. Calculate the energy of a photon with this wavelength.

1 answer:

5 0

First of all, we can calculate the frequency of the photon, which is related to the wavelength by the following equation:
$f= \frac{c}{\lambda}$
where c is the speed of light and $\lambda=670.8 nm=670.8 \cdot 10^{-9} m$ is the photon wavelength. Substituting into the formula, we find the frequency
$f= \frac{c}{\lambda}= \frac{3 \cdot 10^8 m/s}{670.8 \cdot 10^{-9} m}=4.47 \cdot 10^{14} Hz$

Now we can find the energy of the photon with the following equation:
$E=hf$
where h is the Planck constant. Substituting numbers, we find
$E=hf=(6.6 \cdot 10^{-34}Js)(4.47 \cdot 10^{14} Hz)=2.95 \cdot 10^{-19} J$

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Suppose that you want to move a heavy box with mass 30.0 across a carpeted floor. You try pushing hard on one of the edges, but

timurjin [86]

The solution to the problem is as follows:
Normal force is m*g plus 240 N*sin30.
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I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

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3 years ago

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3 years ago

In California the pacific plate slides past the North American plate. If the pacific plate is moving at a speed of 5 centimeters

RUDIKE [14]

Answer:

2000years

Explanation:

We will either convert the distance to centimeters or speed to meters/second.

Converting distance to centimeters: 100 meters= 100*100centimeters =10000centimeters.

time=distance/speed

t=10000/5=2000 years

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3 years ago

Two polarizers are oriented at 68 ∘ to one another. unpolarized light falls on them. part a what fraction of the light intensity

Radda [10]

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3 years ago

Read 2 more answers

Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as 1 kc

IgorC [24]

Answer:

The answers to the questions are;

a. The number of times the student run the flight of stairs to lose 1.00 kg of fat is 829.23 times.

b. The average power output, in watts and horsepower, as he runs up the stairs is 158.026 watts.

c. The act of climbing the stairs is not a practical way to lose weight has to lose 1 kg of fat, the student needs to workout for about 26.49 hrs or 1.104 days.

Explanation:

To solve the question, we write out the known variables as follows

1 g of fat = 9.00kcal

Number of steps the student climbs = 95 steps

Height of each step = 0.150 m

Time it takes for the student to reach the top of the stairs = 57.5 s.

Efficiency of human muscles = 20 %

Mass of student, m = 65 kg

a. From the question, the energy expended by the student in climbing the stairs is the "work done" by the student.

The "work done" is the height climbed resulting in the gaining of gravitational potential energy P. E..

That is work done, W, = P. E. = m·g·h

Where:

h = The total height climbed by the student

g = Acceleration due to gravity = 9.81 m/s²

Therefore;

h = Height of each step × Number of steps the student climbs =

= 0.150 m/(step) × 95 steps = 14.25 m

Therefore, P. E. = 65 kg × 9.81 m/s² × 14.25 m = 9086.5125 kg·m²/s²

= 9086.5125 J

We remember that the efficiency of the muscle is 20 %

The formula for efficiency is

Efficiency = $\frac{Ene rgy Out put}{Energ y In put} \times 100 %$

The work produced by the muscle = Energy Output = 9086.5125 J

Energy input is given by

$\frac{Out put} {Effici ency}$ = 9086.5125 J/ (0.2) = 45432.5625 J

= 45.432 kJ

From the question, 1 g of fat = 9.00 kcal and

1 kcal = 4186 J

Therefore 1 g of fat can release 9.00 kcal × 4186 J = 37674 J

Therefore 1 kg of fat = 1000 g = 1000 × 37674 J = 37674 kJ

To consume the energy in 1 kg of fat the student therefore will run up the foight of stairs $\frac{37674 kJ}{45.432 kJ}$ times to make up the 37674 kJ energy contained in 1 kg of fat

That is $\frac{37674 kJ}{45.432 kJ}$ = 829.23 times

b. Power is the rate of doing work

That is Power output = $\frac{ WorkO utput }{Time}$ = $\frac{9086.5125 J}{57.5 s}$ = 158.026 watts

c. No as the activity student will have to spend a total time of

829.23 × 57.5 s = 47680.67 s climbing up the stairs alone and

47680.67 s = ‪13.24 Hours climbing up of which if the time to climb down is the same s climbing up, then we ave total time = 2× ‪13.24 Hours

= 26.49 hrs = 1.104 days exercising which is not humanly possible.

3 0

3 years ago