Inertia Magic with a Tower of Coins!

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Ready to combine a magic trick with some serious science and engineering?

The coin inertia experiment showcases inertia, a fundamental principle in physics. By striking the bottom coin in a stack, you apply a sudden force, causing it to accelerate. However, due to inertia, the upper coins resist immediate motion change.

The bottom coin moves out, leaving the rest hovering briefly. This illustrates that objects tend to stay at rest or in uniform motion unless acted upon by an external force.

This experiment is sure to give that “wow” factor! Let’s get started!

How to make the Inertia Magic Coin Tower science experiment

Supplies you will need

For this experiment, you will need the following:

  • A stack of coins (15-20)
  • Butter knife

Here’s a kid’s book all about force to read alongside this experiment!

Supplies needed for the Inertia Magic Coin Tower science experiment

Before you start

Small coins can be a choking hazard, so please watch your small children around this experiment.

Instructions

Here is how to do this experiment with your child:

Step 1: Stack all of the coins

First, stack all of the coins, one on top of the other, as straight as you can.

If any of the coins are sticking out, it might make the tower less stable and it will topple over during the experiment.

Stack all of your coins in a neat tower

Step 2: Lay the butter knife on the table at the base of the coin stack

In order to keep our butter knife level and only strike the bottom coin, we want to place the butter knife at the table to strike the bottom coin in the next step.

Lie the knife down on the table at the same level as the bottom coin

Step 3: Quickly strike only the bottom coin

Running the butter knife along the table toward the tower, quickly strike only the bottom coin. You should see the bottom coin shoot out from the stack while the rest of the stack stays intact on the table.

Striking the bottom coin

The science behind the Inertia Magic Coin Tower experiment

This experiment teaches:

  • Inertia
  • Conservation of momentum
  • Fine motor skills

How it works

The coin inertia experiment showcases inertia, a fundamental principle in physics. By striking the bottom coin in a stack, you apply a sudden force, causing it to accelerate. However, due to inertia, the upper coins resist immediate motion change.

The bottom coin moves out, leaving the rest hovering briefly. This illustrates that objects tend to stay at rest or in uniform motion unless acted upon by an external force. It also demonstrates the conservation of momentum, as the total momentum of the system remains constant.

Inertia

The experiment is an excellent demonstration of the concept of inertia. It shows that objects tend to stay at rest or in uniform motion unless acted upon by an external force.

In our case, our coin stack stays at rest before we strike the bottom coin. When we strike the bottom coin, we are only changing the motion of the bottom coin itself, so the rest of the stack stays at rest (after it drops slightly to the table, thanks to gravity).

Conservation of momentum

The experiment also illustrates the principle of conservation of momentum. The coins above the bottom one stay in place initially because they resist changes in their state of motion. This highlights the idea that the total momentum of the system remains constant unless an external force acts on it.

Fine motor skills

Performing the experiment involves coordination and dexterity in handling the coins, which can help improve fine motor skills. If your child is able to work with small coins to build a tower, have them go for it!

More experiments about force to try out with your child

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