Help with easy problems that I just can't seem to get right

  • #1
I think I am doing these right, but I keep getting them wrong...can anyone show me what I am doing wrong.

1. What is the wavelength of a 29.00E9 Hz radar signal.
I did wavelength = c/f = 3.00E8m/s divided by 29.00 Hz and got 0.01034, but it is telling me that it is wrong.


2. An em wave has a wavelength of 850nm, what is the frequency.
I did f = c/wavelength = 3.00E8m/s divided by 850E-9 m and got 3.53E14, and it told me it was wrong.

3. Calculate the frequency of green light with a wavelength of 540nm and yellow light with a wavelength of 580nm. I did freq of green = c/wavelength = 3.00E8/540E-9 and got 5.56E14 which was wrong, and 3.00E8/580E-9 = 5.17E14 which was also wrong.

4. A start is 2.1 light years away. How far is it away in meters? I converted 2.1 years to seconds, and then divided 3.00E8/2.1 years in seconds and got 9.06m, which was also wrong.
I know these problems are easy but I am frustrated with them because I can't get them right, I would really appreciated it if someone could help me out.
 

Answers and Replies

  • #2
1,357
0
supermenscher said:
... but it is telling me that it is wrong.
What is "it"? Are you submitting these answers online or something? Or does "it" refers to the answers in your book? Do you have these answers? Can you post these answers?
 
  • #3
It is submitting the answers online
 
  • #4
1,357
0
Make sure you are submitting your answer in the proper format.
 
  • #5
I am, do you have any other help besides submitting in the correct format
 
  • #6
krab
Science Advisor
893
2
I'm guessing your answers to 1-3 are wrong because you did not enter any units. Number 4 you get 9 metres? The star is 9 metres away? Seriously? Read up on the definition of a lightyear.

Supermenscher, you've started 16 threads in this forum. They all have exactly the same format. You copy a problem verbatim from your assignment and ask us to give an answer. On 4 occasions, you were given a detailed answer and the exact result. On those 4 occasions you said thanks. On the other 12, we tried to get you to solve it yourself. In not one of those 12 did you respond with saying you found the answer as a result of the help. It appears you are not interested in learning physics, only in getting us to do your homework for you. Read the very first thread at the top of this forum again.
 

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