I'd go with electricity source. Good luck!!
I believe it’s a liquid inside a beaker on a hot Bunsen burner (c)
This is because : Everyday Examples of Convection
Boiling water - The heat passes from the burner into the pot, heating the water at the bottom. Then, this hot water rises and cooler water moves down to replace it, causing a circular motion. Radiator - Puts warm air out at the top and draws in cooler air at the bottom.
Not sure if it’s right tho!
Answer:

Explanation:
The two cars are under an uniform linear motion. So, the distance traveled by them is given by:

is the same for both cars when the second one catches up with the first. If we take as reference point the initial position of the second car, we have:

We have
. Thus, solving for t:

Explanation:
The increase in the body temperature of pronghorn, the fastest North American animal, results from the chemical energy of the pronghorn converting into kinetic energy with efficiency less than 100%. The remaining energy is converted into heat energy. Thus, raising the temperature of pronghorn.
Due to the chemical energy it gains both kinetic and heat energy.
A is pulling the block straight down toward the center of the Earth, no matter what the slope of the plane may be. A is the force of gravity.
The directions of B and C both depend on the slope of the plane.
B is a force that's parallel to the plane, pulling the block UP the plane. B is the force of friction.
C is a force perpendicular to the plane, preventing the block from falling down through the plane. C is the normal force.