- Take any backpack
- Put any object inside the backpack, for example a pack of 12 gauge cartridge
- Try putting your backpack in the car
Empty things and bags should take up little space in the car, and take up more space as they fill their internal volume. I assume some difficulty in implementing such a dependency. But at least you need to make it possible to put things and backpacks in a machine with a filled volume, without having to empty the internal volume of the backpack, pants and jacket.