Hi! I have just performed some experiments with my phones accelerometer, and plotted the acceleration as a function of time from the raw data. The experiments I did was: jumping down from a chair jumping from the floor and up let the device fall toward a bed When I analyze the graphs, I think it's strange that the absolute value of the acceleration is more than g during the jumps, but close to g during the free fall (about 1.5g and 2.0g for jump from a 40 cm high chair and straight from the floor, respectively, during the free fall it seems). Can it be something I do during the jump (is technically possible without being stucked to the floor)? During the jumping, the phone was fixed in the waist belt. I attach the 3 graphs. Someone here who has an explanation for the marked strange parts in the graphs (it should be values of about -1, I think)?