Question

As a freely falling object speeds up, what is happening to its acceleration –does it increase, decrease, or stay the same? (a) Ignore air resistance. (b) Consider air resistance.

Short answer

In the absence of air resistance, the acceleration of a freely falling body remains constant and in the presence of air resistance, the acceleration decreases.

Step-by-step solution

Step 1. Definition of free fall

The motion of a body traveling under the sole influence of the earth’s gravity is known as free fall.

Step 2. Determination of the acceleration of the freely falling body in (a) the absence of air resistance

When air resistance is absent (or negligible), all freely falling bodies experience a similar downward acceleration, irrespective of their masses. The acceleration remains constant at$g=9.8\mathrm{m}/{\mathrm{s}}^2$ because the velocity increases at a constant rate.

Step 3. Determination of the acceleration of the freely falling body in (b) the presence of air resistance

Air resistance is a resistive force that opposes the relative motion of a body through air. It depends on the velocity and the surface area of the falling body. In this case, the net acceleration of a freely falling body becomes less than g because the air drag increases with the velocity of the body.