<span>a) 13 seconds
b) 130 m/s
The formula for the distance an object moves while under constant acceleration is d = 1/2AT^2. So let's define d as 830 m, A as 9.8m/s^2, and solve for T
830 m = 1/2 9.8 m/s^2 T^2
830 m = 4.9 m/s^2 T^2
Divide both sides by 4.9 m/s^2
169.3878 s^2 = T^2
Take the square root of both sides
13.01491 s = T
Since we only have 2 significant figures, round the result to 13 seconds which is the answer to the first part of the question. To find out how fast the marble is moving, just multiply T and A together
13 s * 9.8 m/s^2 = 127.4 m/s
Since we only have 2 significant figures, round the result to 130 m/s.</span>
To listen the sound, the air particles must vibrates.
As the sound energy produce vibrations in the medium, so the air column exerts pressure, and then the air molecules set into vibrations and we hear sound as the diaphram set into vibrations.
