Build a ball or pompom run using just cardboard tubes and tape!
This a really creative engineering activity that involves considering the materials you are using to build your structure, thinking about how gravity and friction will act on the marble and solving structural challenges.
All you’ll need is: Cardboard tubes (from toilet, wrapping paper or paper towel rolls – the more you have, the longer your track can be), tape (patch test if using the wall to check it won’t damage the surface – masking/painter’s tape is usually a good option), scissors, wall space or other surface, paper and pencil, a pompom or small ball.
Here’s how it’s done:
1. Using the paper and pencil, draw a design for your track or run. You could also use a ruler to help you be accurate. The track needs to start at the highest point and end at the lowest point, as you’ll be using the pull of gravity to get the ball from the start to the finish point.
Start with a simple design – the ball could zigzag, drop through a hole from one level to another, go down a mix of gentle and steep slopes and so on.
Just make sure the track is always generally going downwards towards the floor (it is possible to have the ball go upwards slightly or over a jump, but you’ll need to make sure it’s going fast enough beforehand, so try having the upwards section after a steep slope).
2. Now build your track by taping the rolls to the wall or your chosen space (we actually used a large cardboard box). Don’t build it all in one go! Test it frequently by putting the ball through it to make sure it works. You can cut some or all of the rolls in half lengthways if you want to be able to see the ball or car making its way down the track. This will give you more cardboard to build the track with too.
3. Now enjoy your finished wall track or run! You can try putting different small balls, small toy cars or other round objects through it, and you can also experiment with different designs.
Get thinking about these questions. Tell someone what you think, and ask them what they think too!
Why do you think the ball travels towards the ground? What would you have to do to get the ball to travel upwards? Is there anything you could do to make the ball travel faster or slower? Were there any parts of your track that made the ball travel more quickly or more slowly? Why do you think that was?
Here’s a rundown of some science behind this engineering challenge!
When you pick up the ball and raise it up in the air, this gives it gravitational potential energy. When you let go of it at the starting point, gravity starts to pull it towards the ground and the energy turns into kinetic (movement) energy. Friction or hitting the sides of the track can slow the ball down as it loses energy. The energy will be converted to heat or sound – which is why you’ll hear the sound of the ball hitting the cardboard, for example.
You want the track to be as smooth as possible so that the ball only loses a small amount of energy to friction and collisions. This will help it to have enough energy to make a jump or loop on the track, or travel upwards.
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