In practice, it is challenging to achieve a completely free and uncontrolled drop of your arm due to the involuntary muscle contractions and reflexes that occur within the body. Even if you consciously try to relax your arm and let it drop, there will still be some level of muscle tension and control involved.
The body's natural response to a falling limb involves reflex actions and muscle contractions to prevent injuries or excessive impact. These reflexes, such as the stretch reflex, can cause muscles to contract and adjust the position of the limb to some extent.
Additionally, the nervous system continuously receives sensory feedback from various receptors in the body, including those in muscles and tendons. This feedback loop helps the body make constant adjustments to maintain balance and control.
While you can consciously minimize the control you exert over your arm during a drop, it is unlikely that you will achieve a completely free and uncontrolled drop due to the involuntary muscle contractions and reflexes that act to maintain stability and protect the body from harm.