when I walk gravity is always acting on me. all day long physics is acting on my body. when you fall you experience this because you are always being tied to the earth by gravity. when you jump in the air your being effected by gravity because you don't just keep going up into space. gravity is constantly bringing you back down to earth. also when you are falling you are constantly falling at a rate of 9.81 m/s2 down once you reach terminal velocity however you can no longer accelerate. however you will most likely not survive the fall at this point.