I think about physics every day but it's not every day that I use the knowledge in a practical way. There is a lot of physics involved in building a car but you don't need to understand the principles you just need to screw the bits together. Maybe Ohm's law might come in handy doing the wiring? Not really. I did use an ohm meter but only to find out where the other ends of the wires are, not to measure resistance. One thing did come in handy. I know that a car battery can deliver a lot of current so must have a low internal resistance, If you short circuit the terminals with a wire, the wire will melt, this doesn't happen with a school power supply. Therefore, when testing car circuits it´s much better to use a 12V lab supply than a car battery. Don't ask how I know this.