One more thing is certain: some beginners will trip up on physics concepts. It’s a new way of thinking, and it takes getting used to.
Dot Physics: Constant Force and Constant Motion
It seems that every semester when this discussion comes up, someone says this:
“Well, I think that a constant force will make the thing go at a constant speed. It just makes sense. Look at your car. You push on the gas pedal with a constant force and the car goes at a constant speed.”
For some reason, the students think of pushing the gas pedal with a constant force as the same as pushing the CAR with a constant force. Perhaps this is because the gas pedal is part of the car. Maybe they are just trying to bring one of their own experiences into the discussion.
I don’t think that this is unreasonable — a constant amount of gas to the engine should mean a constant force. But it’s not the only force, since there is air resistance and rolling friction balancing the effect of the engine. I think that the problem is more the difficulty in conceptualizing a single force without any other forces on the object — we don’t have much experience driving in a vacuum.
TThe modern gas pedal is typically fly-by-wire talking to the engine oxygen sensor. The oxygen sensor then adjusts fuel-air ratio. If the conversation bogs down, the driver can stomp and prod hardware all he likes – software doesn’t care.
Every car dashboard must include a big red mushroom-shaped button. Hit the button and a shaped charge severs the drive shaft. This could be inconvenient re playful children, sloppy drunks, and agile paramours. Said button shall be under a locked polcarbonate shield only disengaged by insertion and left-right-left turning of the ignition key in the shield’s lock. This brings up a glass cockpit alphanumeric keypad. Enter the five character case-sensitive factory-installed PIN and the shield disengages.
Prototypes disclose button subfunction if hit dead on. Coming in at a 25.7-degree angle from the passenger side works best. Buckling the center rear seat belt sometimes soft-triggers the button, but not often, mostly.