In a string of length L, the wavelength of the n-th harmonic of the standing wave produced in the string is given by:
The length of the string in this problem is L=3.5 m, therefore the wavelength of the 1st harmonic of the standing wave is:
The wavelength of the 2nd harmonic is:
The wavelength of the 4th harmonic is:
It is not possible to find any integer n such that 
, therefore the correct options are A, B and D.
Answer:
fo = 378.52Hz
Explanation:
Using Doppler effect formula:
where
f' = 392 Hz
C = 340m/s
Vb = 20m/s
Va = 31m/s
Replacing these values and solving for fo:
fo = 378.52Hz
The answer is c: <span>1960 J
</span>Potential Energy :
<span>PE = m x g x h = 40*9.8*5=1960
</span>
Action-reaction pairs.
This is in reference to Newton’s second law of motion.
It would be best to cover the cardiac, smooth, and skeletal muscles! =)
