In terms of inertia what happens when a card is flicked away?

Answer 1

Inertia affects everything all the time. One way to look at inertia is that it is the "change of state" of a thing regarding its motion, or lack of motion. If we move something that was still, stop something that was moving, or change the speed or direction of travel of anything that is moving, we are effecting an inertial change. We're changing the inertia of the object. Make sense? Before a card is flicked away, it starts from a stationary point. Its inertia is that it is not moving and does not want to move unless it is acted on by an outside force. When it is actually flicked away, it is accelerated by the fingers to set it in motion. It will be launching, and it will begin to move away from the fingers, and it will begin to spin. During this acceleration, it gains energy. We say that its inertia, that is, its inertial moment, has changed. The card is now in flight, and, because it is moving, it will not want to stop. It now is in a new inertial state. It used to be still, and now it's moving (and spinning). Remember that inertia is the resistance to a change of motion - any motion. Any change of motion. In flight, the card is being acted on by two forces. One is gravity. The other deals with the complex forces applied to the card by air. The air is stationary (mostly), and the card is moving through it and is spinning. The air will affect the flight of the card (change of direction), and will cause the card to slow down. The card is pushing air out of the way to move through the medium. Air resistance is affecting the flight of the card. The card's spin and the affect of the air also cause subtle forces to act on the card and change its direction of flight. All of the effects of air on the card cause its inertia to change. Gravity continuously pulls the card down, and eventually the card comes to a stop. The card has shed all its energy. The card had an inertial moment associated with it being still in the hand. It was then accelerated when energy was applied to overcome its "inertia of stillness" and launch it. Our card was in motion, and it had the "inertia of movement" as it flew. Then the card was acted on by air and by gravity, and its direction was changed, changing its inertia. Also, the energy it had was gradually being stolen by air resistance, which acted to change its inertia again back toward "stillness" like at the beginning. Finally, our card is pulled out of the air (gravity is changing its inertia all the while) and it hits something and stops. All its energy has been removed. It has returned to the inertial state it had at the beginning of its flight.