Ch.1 #41 [ENDORSED]

[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.

[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 :)

[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.

[Yadira Flores 1G]

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

[ErinKim1I]

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

[Emely Reyna 1F]

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

[Aman Sankineni 2L]

The answer is 3956 m/s.

[Sabrina Galvan 3J]

The answer to this solution actually requires three sigfigs, signified by the dot at the end of 100. pm. Therefore the answer is 3960 m/s