The echo is heard 2.80 s later, this means this is the time the sound takes to travel to the reflecting object and then back to us. So, during this time, the sound wave has covered the distance L between us and the object twice:

The speed of the sound wave is:

, and since it is moving by uniform motion, we can find the distance covered by the wave using

And we said this corresponds to twice the distance between us and the reflecting object, so:

so, the object is 480 meters away.
Answer:
<em>c. ABBA counterbalancing
</em>
Explanation:
The student should not use the method because it is a progressive error management technique for each subject by introducing all <em>treatment circumstances twice, first in one sequence, then in the other (AB, BA) by subject counterbalancing.</em>
If participants experience conditions more than once, they experience the conditions first in one order, then the opposite order.
Answer:
High amplitude is equivalent to loud sounds.
Explanation:
Answer:

Explanation:
From the question we are told that:
Distance of wall from CD 
Second bright fringe 
Let
Strontium vapor laser has a wavelength \lambda= 431 nm=>431 *10^{-9}m
Generally the equation for Interference is mathematically given by

Where


