Answer:
the mass of the air in the classroom = 2322 kg
Explanation:
given:
A classroom is about 3 meters high, 20 meters wide and 30 meters long.
If the density of air is 1.29 kg/m3
find:
what is the mass of the air in the classroom?
density = mass / volume
where mass (m) = 1.29 kg/m³
volume = 3m x 20m x 30m = 1800 m³
plugin values into the formula
1.29 kg/m³ = <u> mass </u>
1800 m³
mass = 1.29 kg/m³ ( 1800 m³ )
mass = 2322 kg
therefore,
the mass of the air in the classroom = 2322 kg
Answer:
-48 N
Explanation:
mass of door (m) = 4 kg
acceleration of the door = 12 m/s^{2}
force exerted by the person = 48 N
From Newton's third law of motion, action and reaction are equal but opposite. Therefore the force exerted on the door by the person which is 48 N will be the same as the force exerted on the person by the door but opposite in its direction, and this would be - 48 N
<span>So we want to know what will happen when the fast moving car that is making loud noise that is initially approaching the person, passes the person and starts to move away. So Doppler effect is a phenomenon where when the source of a sound is approaching a person, the person hears the sound as higher than if the source was standing still with respect to the person because the wavelength is getting shorter, and as the source is moving avay from the person the sound is getting deeper because the wavelength is getting longer. So the correct answer is A. </span>
