Dropping a coin into an empty glass sounds pretty ordinary at first. How about trying out a more creative and scientifically sound way to get a penny into a cup? This experiment will demonstrate Newton’s law of inertia. You will need a notecard, an empty glass, some coins and safety glasses.
Place the card on top of the glass. Make sure there is enough space to give one edge of the card a good flick without smacking your finger on the glass. Place a single coin on top of the card so that it rests over the cup’s opening.
Flick an exposed edge of the notecard. Don’t flick the card from underneath. Flick directly from the side of the card’s edge. The coin drops straight into the glass.
Newton’s first law of motion can be summed up like this: an object at rest will stay at rest unless an outside force acts upon it. An object that is moving will stay moving until something stops it. In the case of our coin drop trick, the coin is at rest while it sits on top of the card and glass. When you flick the card out from under the coin, you enable gravity (an outside force) to act upon the coin and pull it into the glass.
When the coin drops, the bottom of the glass stops the coin. That doesn’t explain why the coin doesn’t take off with the card though, does it? If you flicked the card right, it slides out from between the glass and coin without enough friction to pull the coin with it.
Try challenging yourself to drop as many coins as possible into the cup using this method. What’s your record? Does the type of coin you use matter? Is there a type of card that doesn’t work? Try flicking index cards, Pokemon cards, or whatever you can think of.
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