Answer:

Explanation:
From the conservation of mechanical energy




Solve to velocity v2




λ=v/f
λ-wavelength
v-speed
f-frequency
we have the wavelength(6.2 x 10^-6meters) and we use the speed of light which is equal to 3*10^8m/s
6.2*10^-6m=3*10^8m/s/f
f=(3*10^8m/s)/(6.2*10^-6)≈0.48*10^14Hz
Answer:
434 Hz
Explanation:
According to the Doppler effect, when a source of a wave is moving towards an observer at rest, then the observer will observe an apparent frequency which is higher than the original frequency of the source.
In this situation, Tina is driving towards Rita. Tina is the source of the sound wave (the horn), while RIta is the observer. Since the original frequency of the sound is 400 Hz, Rita will hear a sound with a frequency higher than this value.
The only choice which is higher than 400 Hz is 434 Hz, so this is the frequency that Rita will hear.
Answer:
I think the answer is
C) iron nails are attracted towards all materials