I'm learning about thermodynamics for the first time and have reached the chapter regarding expansion of materials due to change in temperature but an example in the book isn't adding up with the information they've provided already.
The example states that the mass of gasoline in a fuel tank in summer is less than in winter because it's expanded but that doesn't make sense to me. Like, if the tank had 10 litres of fuel in it, it would expand in the summer due to the higher temperature and therefore appear on the gauge as if you have more fuel than you actually do. In winter however, the gasoline hasn't expanded and so it appears like you have less fuel but the actual mass of gasoline hasn't changed, it's still 10 litres. The density would've changed because the volume has changed but the mass would still be the same, right?
Could someone explain what I'm missing?