An object accelerating only under the force of gravity is a) free fall or b) acceleration due to gravity

-- An object acted on by only the force of gravity, on or near Earth's surface,
accelerates downward at the rate of about 9.8 m/s² without air resistance. 

-- That number is "the acceleration due to gravity, on Earth".

-- The object in that situation is said to be in "free fall".

Electoral current force mechanical advantage if the wheel and axle is 2 n and the output force is 20 n