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### Ch.1 #41

Posted: **Thu Oct 12, 2017 11:24 pm**

by **Jocelyn Martinez-1K**

We are asked to "find the velocity of a neutron of wavelength 100. pm" so we set the equation to v=h/mλ. So h=6.62608x10^-34, λ= 100 (given), and m=1.67493x10^-27 kg. My question is where did we get 'm' from? Is m a constant? Looking for clarification of where we get m=1.67493x10^-27 kg.

### Re: Ch.1 #41 [ENDORSED]

Posted: **Thu Oct 12, 2017 11:34 pm**

by **Gwen Peng 1L**

So yes the mass of a neutron is always constant. The mass of a neutron is 1 amu. Therefore you convert this to kilograms and get:

1 amu = 1.67493x10^-27 kg

Hope this was helpful :)

### Re: Ch.1 #41

Posted: **Sun Oct 15, 2017 11:42 am**

by **Lily Sperling 1E**

Yes, Gwen is correct. The mass of a neutron, like that of a proton, or planks constant, or Avogadro's number are all constant and therefore, will not change. The mass of a neutron is typically given in grams, so you have to convert by dividing by 1000 in order to get kg.

### Re: Ch.1 #41

Posted: **Tue Apr 17, 2018 11:06 am**

by **Yadira Flores 1G**

You have to convert the picometers into meters before plugging it into the equation right?

### Re: Ch.1 #41

Posted: **Sat Apr 21, 2018 10:22 am**

by **ErinKim1I**

Yes, you have to convert picometers to meters because m is the standard SI unit

### Re: Ch.1 #41

Posted: **Sun Apr 22, 2018 7:47 pm**

by **Emely Reyna 1F**

to convert from pm to m in order to use the equation you can multiply 100 pm by 10^-12

### Re: Ch.1 #41

Posted: **Sun Nov 03, 2019 9:39 pm**

by **Aman Sankineni 2L**

The answer is 3956 m/s.