Sapling Homework week 2 problem 5


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Lucy Weaver 1K
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Sapling Homework week 2 problem 5

Postby Lucy Weaver 1K » Fri Oct 23, 2020 3:52 pm

HI! I'm having a lot of trouble solving the 5th problem on sapling.

I muplipled planks constant by the speed of light, got 1.98644582 × 10-25 m3 kg / s2, then divided that by 9.33 * 10^-4 to get E. I found that E= 2.13 *10^-22.Then I divided that by 100 to turn it from centimeters to meters. I got 2.13*10^-24. Then I divided 51.5/2.13*10^-24 and it is giving me an incorrect.

I am not sure what I'm doing wrong, so if someone is able to help me understand that would be great!
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Lucy Wang 2J
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Re: Sapling Homework week 2 problem 5

Postby Lucy Wang 2J » Fri Oct 23, 2020 4:22 pm

Hey! I think you are doing it correct but you just need to convert from cm to m before you find Energy (J).

HannahRobinson3L
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Re: Sapling Homework week 2 problem 5

Postby HannahRobinson3L » Fri Oct 23, 2020 4:22 pm

Hi! I think you have to convert the wavelengths from cm to meters before you calculate the energy, or else you end up with a different answer. If you convert the wavelength first, you should get an energy of 2.13*10-20. Hope this helps.

Margia Adriano 2A
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Re: Sapling Homework week 2 problem 5

Postby Margia Adriano 2A » Fri Oct 23, 2020 4:23 pm

Hi! I think you should try (Planck's constant)(speed of light)/(9.33*10^-6) instead of (Planck's constant)(speed of light)/(9.33*10^-4). When you divide the latter by 100 instead of doing it like the former equation, I believe you get different answers. Hope this helps! If I'm wrong, please correct me!

Emma Strassner 1J
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Re: Sapling Homework week 2 problem 5

Postby Emma Strassner 1J » Fri Oct 23, 2020 4:26 pm

HannahRobinson2L wrote:Hi! I think you have to convert the wavelengths from cm to meters before you calculate the energy, or else you end up with a different answer. If you convert the wavelength first, you should get an energy of 2.13*10-20. Hope this helps.


Hi, I agree with this. Converting from cm to meters first is necessary to get the right answer for E. If you wait until after you won't be converting the right units, which is why you would get the wrong answer.

idella 1D
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Re: Sapling Homework week 2 problem 5

Postby idella 1D » Fri Oct 23, 2020 6:27 pm

Where do you get the 9.33x10^-6 from?

Melanie Lin 3E
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Re: Sapling Homework week 2 problem 5

Postby Melanie Lin 3E » Sun Oct 25, 2020 3:02 pm

idella 1F wrote:Where do you get the 9.33x10^-6 from?

Hi Idella! The problem said that the wavelength was 9.33x10^-4 cm so you have to convert it to meters before plugging it into the E=hc/wavelength. In meters, the wavelength would be 9.33x10^-6.

idella 1D
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Re: Sapling Homework week 2 problem 5

Postby idella 1D » Sun Oct 25, 2020 10:06 pm

Melanie Lin 3B wrote:
idella 1F wrote:Where do you get the 9.33x10^-6 from?

Hi Idella! The problem said that the wavelength was 9.33x10^-4 cm so you have to convert it to meters before plugging it into the E=hc/wavelength. In meters, the wavelength would be 9.33x10^-6.


thank you! i really appreciate it :')

AlyssaMaynard1C
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Re: Sapling Homework week 2 problem 5

Postby AlyssaMaynard1C » Sun Oct 25, 2020 11:54 pm

Margia Adriano 3C wrote:Hi! I think you should try (Planck's constant)(speed of light)/(9.33*10^-6) instead of (Planck's constant)(speed of light)/(9.33*10^-4). When you divide the latter by 100 instead of doing it like the former equation, I believe you get different answers. Hope this helps! If I'm wrong, please correct me!

Where is the 9.33*10^6 coming from?

AlyssaMaynard1C
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Joined: Fri Mar 06, 2020 12:15 am

Re: Sapling Homework week 2 problem 5

Postby AlyssaMaynard1C » Sun Oct 25, 2020 11:55 pm

Melanie Lin 3B wrote:
idella 1F wrote:Where do you get the 9.33x10^-6 from?

Hi Idella! The problem said that the wavelength was 9.33x10^-4 cm so you have to convert it to meters before plugging it into the E=hc/wavelength. In meters, the wavelength would be 9.33x10^-6.

I'm seeing the wavelength as 851nm on the question

Juliana Rosales 1H
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Re: Sapling Homework week 2 problem 5

Postby Juliana Rosales 1H » Sun Nov 01, 2020 11:01 pm

I had trouble with this one too! Lol

Juliana Rosales 1H
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Joined: Wed Sep 30, 2020 9:43 pm

Re: Sapling Homework week 2 problem 5

Postby Juliana Rosales 1H » Sun Nov 01, 2020 11:02 pm

I had trouble with this one too! Lol


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