Don’t try this at home (even if you are an expert bus driver). Driving on two wheels is only a gendanken problem for a physics course. How the centre of gravity of a ‘bus’ changes with the position of the load (f.ex. the passengers)? Let’s draw a bus on a piece of paper and stuck it to thick card. Add two 10 g masses clipped to the bottom in order to simulate the mass of the engine. The centre of gravity is measured using the standard school method. Students can observe the angle at which the line of action of the centre of gravity acts outside the base. They can see that if the passengers all sit on the top deck, then the centre of gravity rises and the bus becomes unstable. Drivers can use this to perform stunts (as shown in the youtube video above). There is always a trick behind it. John Kinchin, “Investigation into the centre of gravity and stability of a bus,” Phys. Educ. 45: 577-578, 2010. Note that your students could substitute the bus by another vehicle, f.ex. a trunk, see below.