**Free-Fall Acceleration**

Free-Fall Acceleration An important example of straight-line motion with constant acceleration is that of an object rising or falling freely near Earth’s surface. The constant acceleration equations describe this motion, but we make two changes in notation: (l) we refer the motion to the vertical y axis with +y vertically up; (2) we replace a with – g, where g is the magnitude of the free-fall acceleration. Near Earth’s surface. g = 9.8 m/s2 (= 32 ft/s2).

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