Answer:
C. it will not change.
Explanation:
While combing, the rubbing of the comb with the hair, transfer of electron takes place from the hair to the comb and the comb becomes negatively charged. But, this transfer of electron does not make any considerable change in the mass of the hair. This is because the mass of an electron is highly negligible. Now, neglecting the mass of an electron, the transfer of the electrons from the hair to the comb makes charging of the comb, but no loss of mass in the hair. So, the mass of hair will no change.
Answer: 0.4 m
Explanation:
Given
Speed of ambulance, vs = 61.9 m/s
Speed of car = 28.5 m/s
Frequency of ambulance siren, f = 694 Hz
Velocity of sound in air, v = 343 m/s
With speed of ambulance being (61.9 m/s) -> We solve using
fd = f(v + vr) / (v - vs), where vr = 0
fd = 694 * (343 + 0) / (343 - 61.9)
fd = 694 * (343 / 281.1)
fd = 694 * 1.22
fd = 847 Hz
Recall,
λ = v/f
λ = 343/847
λ = 0.4 m
Therefore, the wavelength of the sound of the ambulance’s siren if you are standing at the position of the car is 0.4 m
