Center of Mass and How it Works!

Unlock the wonders of balance with your Rope Runner! 🌟 Every part of it, from the wheels to the weights, is designed to find the perfect point where it all evens out—this is the Center of Mass. 🎯 Located directly under the rope, it’s like a magic spot that keeps your runner gracefully dancing in the air. 🕊️

And those wooden balls? They’re not just pretty; they pull the center of mass down low, helping your Rope Runner stay upright. It’s like a tightrope walker using a pole for balance! 🤹‍♂️

Remember, if your Rope Runner is leaning or flipping, it’s all about the science of weight distribution. Adding too much decor on one side or the top might just tip it over—so decorate smartly! 🌈✨ It’s a fun way to learn about gravity’s pull—straight down, keeping your runner on track unless you add a twist! Can you experiment and find out the best way to keep it balanced? It’s a challenge that combines creativity with physics! 🚀🔍

What is Gravity?

Mass vs. Weight

Gravity 🌌 is a force that pulls objects together. Everything in the universe has gravity: the stars ✨, the sun ☀️ and moon 🌙, our Earth 🌎, even you have gravity. Gravity is a “UNIVERSAL FORCE” 🔄.

In everyday life, what we mostly notice is the Earth’s gravity 🌍 pulling on us. But, we too, are pulling the Earth 🤲. The Earth’s pull is much stronger than ours, though, because it has so much MASS ⚖️. Objects with small mass do not pull very hard, which is why you don’t see pencils ✏️ clinging to your fingers, or your breakfast 🍳 stuck to your plate.

Gravity can reach over huge distances. The Earth and the sun are 93 million miles apart 🛣️, but their combined gravitational force is strong enough to keep our planet from flying right out of the SOLAR SYSTEM 🌌. Even tiny Pluto, 3.6 billion miles from the sun, is held in its orbit because of the sun’s mighty gravitational field! ☀️🪐

Mass is the amount of MATTER 🧱 in an object. The amount of matter depends on how many ATOMS ⚛️ there are. These atoms can be squeezed tightly together, in something dense, like a rock 🪨. Or they can have big spaces between the atoms, like in a piece of cotton 🌬️. If you had pieces of rock and cotton that were the same size, the rock would have the greater mass.

The amount of gravitational force pulling any two objects together depends on the amount of their MASS—the greater their combined mass, the greater the attraction 🧲.

Weight is similar, but not quite the same thing as mass. Weight is a measure of the pull of gravity on an object 🌍. The pull we usually think of is that of the Earth, since that is where we usually are standing. But on planets with different mass, you would have a different weight 🌌. And in outer space, far from any major gravitational pull, you would weigh virtually nothing 🛸!

For further exploration visit: 🚀

Center of Mass Practice

Sometimes the center of mass is not where you’d think, try making this gravity-defying Songbird.

You need:

  • A copy of picture of a songbird
  • (It should measure 4 1/2″ X 5 1/2″)
  • 2 Standard paper clips
  • 1 pencil
  • Sissors
  • Crayons or Markers (Optional)

Click to Enlarge the Songbird for Printing


  1. Cut out the 2 paper designs ✂️, Roll the tube with the face-side out, up to the line and tape 📏📜
  2. Tape one end shut 🛑
  3. Drop the marble in 🌌, and tape the other end shut.
  4. Use the other paper as a stencil to trace Trudi onto the felt 🖍️
  5. Cut Trudi out, being very careful cutting the slits ✂️
  6. Stop before the edge of the felt! ⚠️
  7. Slide the tube into the slits as shown 👆
  8. Then roll Trudi down a ramp covered with fabric! 🛹🎀