Cumulonimbus clouds are associated by severe weather. They are thunderstorm clouds that bring heavy rain, snow, hail, lightning and even tornadoes.
Answer:

Explanation:
Ok, the average speed can be calculate with the next equation:
(1)
Basically the car cover the same distance "d" two times, but at different speeds, so:

and the total time would be the time t1 required to go from A to B plus the time t2 required to go back from B to A:

From basic physics we know:

so:


Using the previous information in equation (1)

Factoring:
(2)
Finally, replacing the data in (2)

Do you remember this formula for the distance traveled while accelerated ?
<u>Distance = (initial speed) x (t) plus (1/2) x (acceleration) x (t²)</u>
I think this is exactly what we need for this problem.
initial speed = 20 m/s down
acceleration = 9.81 m/s² down
t = 3.0 seconds
Distance down = (20) x (3) plus (1/2) x (9.81) x (3)²
Distance = (60) plus (4.905) x (9)
Distance = (60) plus (44.145) = 104.145 meters
Choice <em>D)</em> is the closest one.
Convection. When a fluid such as air or water touches a hot object, it can heat up and then move in bulk as a fluid, thereby carrying the heat quickly to new locations. Hot air rising is a common example of heat convection.