(Last Friday) (I know, I've been lazy, shut up!)
The Chicken: Hey Dad?
Me: Hey Chicken.
Chicken: Do you know how the gas makes the car go?
Me: Yes.
Chicken: Will you tell me?
Me: It's kind of long. Are you going to pay attention?
Chicken: Yes.
Me: Ok. You know how we put the gas into the gas tank, right?
Chicken: Yes.
Me: There's a pump, the fuel pump, that pulls the gas out of the tank and through the fuel line up to the engine.
In the engine the gas goes into the fuel injectors where it's mixed with ordinary air. See, the car runs on air with a little gasoline added. It's about 14:1 air to gas and it's called the "fuel/air mixture."
From there the mixture goes into the cylinders, where combustion happens. Cars are "four stroke" engines, meaning that each piston has four states.
The first is intake, where the piston drops down and creates vacuum pressure to pull the mixture into the cylinder.
Then the valves at the top of the cylinder close and the second stroke begins: compression. The piston moves up to squeeze the mixture.
The third is the power stroke. The spark plug will create, well… a spark inside the cylinder. This makes a little explosion as the mixture ignites. The piston is forced downward, creating all the energy of the engine.
The fourth is exhaust, where the other valve at the top of the cylinder opens and the piston moves up to push out the leftover gases from the power stroke.
Each of the pistons is connected at the bottom to a rod called the cam shaft. The movement of each piston is linked to all the others. When one piston is moving down, another is being pushed up. The little explosion from one piston's power stroke creates the force used in another piston's compression stroke. All of the pistons firing together create a continuous rotation on the cam shaft.
The cam shaft runs into the transmission where a series of gears will adjust how the motion of the cam shaft is used, like different gears on a bicycle.
Different cars do the next part in different ways, but basically the transmission connects to the axle and turns the rotation of the cam shaft into rotation of the axle. The wheels are connected to the axle, so when that turns the car rolls down the road.
(pause)
Me: You understand?
(pause)
Me: Chicken?
Chicken: Oh, sorry, I wasn't listening. Tell me again.
(Tuesday night)
Chicken: Mom?
Bunny: Yeah?
Chicken: Do my nails look girly?
Bunny: Your finger nails?
Chicken: Yeah.
Bunny: Lemme see.
(He shows her)
Bunny: They're getting long. They do look a little girly. We should trim those when we get home. Will you remind me to trim your nails when we're at home?
Chicken: I don't want my nails trimmed! How am I going to scratch myself?