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.
Weight is a force caused by gravity. The weight of an object is the gravitational force between the object and Earth.
To solve the problem it is necessary to identify the equation in the manner given above.
This equation corresponds to the displacement of a body under the principle of simple harmonic movement.
Where,
PART A) Our equation corresponds to
Therefore the value of omega is equivalent to that of
From the definition we know that the period as a function of angular velocity is equivalent to
This same point is the equivalent of the maximum point of the speed that the body can reach, since the internal expression of the 
Is equivalent to . So the maximum speed that the body can reach is,
Therefore the maximum felocity will be 5ft / s
PART B) The period of graph is the time taken to reach from one maximum point to next point maximum point, then
Answer:
Convection currents are the result of different heating. Lighter material (warm) rises while heavier (cold) material sinks. This movement of the materials is what causes convection currents! (BTW, it happens in water, in the atmosphere, and in the mantle of Earth!
Explanation:
I hope this helps a little! :)
