Answer:
Explanation:
The change of frecuency of sound due to the movement of the source is colled Doppler Effect.
As James (the source) is running toward the wall, the frecuency reaching the wall (so the eco sound) will be higher than the source. In this case the frecuency at the wall will be:
where is the speed of source, 2 m/s
and is the speed of sound, given that we have wind movind the air in the opposite direction respect to the wall, the speed of sound would be:
Replacing the values:
Now the wall becames the new source, and James (the observer is aproaching the source), for an observer aproaching the source the new frecuency will be:
Now the waves are traveling in the direction of wind, so the velocity of sound will be:
Replacing:
If you look at the units of density, g/cm^3 you will see it's grams divided by volume (cm^3).
218.9 g / (0.5*1.55*25 cm^3) = 11.3 g/cm^3
i think its a, good luck on your test
In air, you'd call it air resistance, pilots call it drag. In water, some call it
water resistance, or just plain drag.
Whatever it's called, it's the friction between the object and the fluid, plus
the force needed to push the fluid out of the way to let the object get through.