The braking car problem: A challenging and stimulating test bench for beginning mechanical engineering students

Introductory courses of physics should provide engineering students – especially mechanical engineering students – with a working knowledge of the laws of conservation of mechanical quantities, plus the capability of analyzing the kinematics and dynamics of simple mechanical systems (for instance, rolling wheels, which are a basic component of innumerable machines). Moreover, introductory courses of physics should teach the principle of relativity of classical mechanics which – within limits – allows to switch from an inertial reference frame to another. Experience proves that this is not always the case. The braking car problem is a challenging exercise which stimulates the ingenuity of beginning mechanical engineering students with its paradoxical nature. At the same time, the problem stress-tests their understanding of the basic tenets of mechanics and thermodynamics, preparing them for more advanced technical topics such as gears, cams, hydraulic machines, jet propellers.