In this study, the intuitive physics of free fall was explored using Information Integration Theory and Functional Measurement. The participants had to rate the speed of objects differing in mass and height of release at the end of an imagined free fall. According to physics, falling speed increases with height of release but it is substantially independent of mass. The results reveal that the participants hold a strong mass-speed belief, i.e., they believe that heavier objects fall faster than lighter ones. Mass and height of release are integrated according to a multiplicative rule. The results are interpreted as providing support to the hypothesis of the perceptual-motor origin of the mass-speed belief. Implications of the results for physics education are discussed.