How Does It Work
Inertia comes from Newton’s First Law of Motion. An object in motion (or at rest) tends to stay in motion (or at rest) unless a force acts on it to change its speed, to stop it, to change its direction, or to get it moving. This means that the balanced bottle wants to stay in the position it has and you want to help it do that to get the cash. In other activities, you’ve seen how some sudden, quick motions have been used to overcome inertia successfully. The key to safely removing the bottle from the money this time, however, is just the opposite: slow and steady wins the race. When you attempt to remove the dollar bill by pulling it out, you apply an outside force that causes the bottle to topple every time. Game over.
This is a case where friction takes center stage and you have to work around it. There is some serious friction between the bill and the bottle and the bill and the tabletop . There is so much friction, in fact, that the bill pulls the empty bottle with it every time. To reduce the impact of friction, you have to roll the currency right up to the edge of the bottle opening and then nudge and coax the bottle to slide a little as you roll. This process is slow-moving, but doesn’t provide enough force to tip the bottle.
