Translate please, i’d be able to help better:)
Answer:
835.29 Hz
Explanation:
When moving towards the source of sound, frequency will be given by
f*=f(vd+v)/v
Where f is the freqiency of the source, vd is the driving speed, v is the speed of sound in air, f* is the inkown frequency when moving forward.
Substituting 800 Hz for f, 340 m/s for v and 15 m/s for vd then
f*=800(15+340)/340=835.29411764704 Hz
Rounded off, the frequency is approximately 835.29 Hz
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➷ After 10,000 years the mass will be:
1,000 / 2 = 500
After 20,000 years the mass will be:
500/2 = 250
As you can see, the correct answer would be A. 20,000 years
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Any of the above depending on the direction of forces