Ever wonder why it’s harder to maintain your balance when you have a heavy backpack? It is hard to tip a toddler’s sippy cup over. How does tightrope walker manage their amazing circus acts? You might also want to learn how to reduce the likelihood of your toy car tipping over while racing around a curve. This activity will teach you how to balance marshmallows, toothpicks, and skewers. For some delicious, sticky, balanced fun, read on!
Everything has to do with how much weight an object is distributed. It might be easy to stand on the curb edge with a heavy backpack in front of your face, but it becomes more difficult if that backpack is higher up on your back. These scenarios change the way your backpack and center of mass change.
The center of mass is the point at which the object’s entire mass can be represented as being concentrated in physics. It is the average weight of all the mass particles in the object. If the mass is evenly distributed, such as with a hula hoof, it will be at the center of the object. However, it can shift to the heavier side of an item if the mass distribution is uneven (such as with a car). Sometimes the center of mass can be defined as a point in space that is not connected to the object. The center of mass in a hula hooper is, for example, its empty middle.
* Large marshmallows
* Two bamboo or wood skewers. Be careful with sharp edges.
* A pen or pencil and paper
Place one marshmallow on each end of a skewer. Try to balance the structure with your finger by placing the tip of the finger underneath the middle marshmallow. Is it possible to balance it? Is it difficult or easy? If it is difficult to balance, you can move the middle marshmallow slightly to one side or another until you reach the spot where you are able to balance the structure using your finger. This spot will be called the original balance point.
Each end marshmallow should be poked with a toothpick. Connect one marshmallow to each end of each toothpick. Then, connect the two new marshmallows together with another skewer to create a rectangular shape.
Put your finger below the original balance point of your rectangular structure. The structure should be at the bottom. Is it possible to balance it? Do you find it more difficult or easier to balance the simpler structure? You can balance the rectangle by moving the middle marshmallow slightly to one side until you are able.
You can draw the structure on a piece of paper. Then, balance it by placing your finger back under the original balance point. Is it horizontal or tilted? Rotate the paper you are drawing on to ensure it is at the same angle as the actual structure. Mark the location of your finger with an “X” on your drawing, and then draw a vertical line from that point.
Balance the structure by placing your finger under one of the toothpicks. Do you see the structure hanging vertically? Or is it tilted? Rotate the paper you are drawing on to ensure it is at the same angle as the actual structure. Draw a vertical line from the X to mark your finger.
Balance the structure by placing your finger under the marshmallows at the corners. Do you see the structure hanging vertically or tilted? Rotate the paper you are drawing on to ensure it is at the same angle as your actual structure. Draw a vertical line from the X to mark your finger.
* The center of mass for your structure is located in the area where three lines intersect on your drawing. What is the location of the center mass in your structure? It is located in relation to the middle marshmallow.
Reorient the structure so that your middle marshmallow is at the top. Attach two marshmallows clustered close to the middle marshmallow using toothpicks. Try to balance the balance point by placing your finger below it. Is it possible to balance it? Do you find it more difficult or easier than the balance of the previous structure?
* Continue the previous steps to draw the intersections of the lines and determine the center mass. The center mass of your new structure is located based on your drawing. It is located in relation to the middle marshmallow. How has it changed? What do you think the reason is?
* Additional: Make other structures with marshmallows, toothpicks, and skewers. What is the center mass for your other structures, and what are its dimensions? You can alter it by adding marshmallows at specific locations.
* Additional: Look for non-symmetrical objects like a toy truck and determine how their mass distribution affects their stability. How will the weight of the toy truck be affected by its position on a hill?
* Additional: Now, use a skewer to place one marshmallow at each end and one in the middle. Use toothpicks for stacking marshmallows on top. Each time you add another marshmallow, balance the structure with your finger. Can you stack more marshmallows until the structure is no longer balanced? You can make other structures and stack marshmallows until they become unstable. Are there other structures that can hold more marshmallows?
Results and observations
Did you notice that the original rectangular structure’s center of mass was right below the middle marshmallow? Did you notice a shift in the center of mass when you added two marshmallows to the middle marshmallow?
A vertical line drawn from the center of mass to balance an object will make it more stable. The balance point is the spot marked with an X. This was where your finger was. The vertical line from the center of mass to the object’s center of mass passes through the balance point. This vertical line is also called the plumb line. You can determine the center of mass by finding the intersections of the vertical lines. The first rectangular structure had its center of mass at the bottom of the middle marshmallow. The second rectangular structure was located higher up within the middle marshmallow. The center of mass should have been moved higher by adding two marshmallows to the top of the middle marshmallow. A balanced object is one that has its center mass below the balance point. It should also be stable if it is higher than the balance point. Therefore, the original rectangular structure with three marshmallows should be less stable than those made from two marshmallows.