Home STEM project relating to forces and motion. Below are the step by step instructions presented on the video. #homeeducation #stemprojects #funstemactivity

Home STEM Project No. 1 – Balloon Buggy

You’ll need:
Corrugated cardboard, thin card, a plastic tube about 16 cm long (e.g. garden hose – you can cut this off with large scissors or ask an adult to cut it with secateurs, or a felt tip pen tube), 2 round pencils or crayons (16cm or longer), 4 plastic milk bottle lids, a balloon, a small rubber band.

Tools need:
Ruler, scissors, Blu Tack (or modelling clay or Playdough), round felt tip pen (bigger diameter than pencil/crayon), Sellotape

Step 1: make the base
Mark out and cut a rectangle 9cm x 14cm from the cardboard.

Step 2: make the bearings
Mark and cut two pieces of card 5cm x 11cm. Wrap each piece in turn round the felt tip pen. Tape round both ends and then tape along the seam. Check the pencil spins easily in the bearings.

Step 3: make two wheels
Place a bottle lid, open end up, on the Blu Tack. Press straight down with the pencil to make a hole in the middle. If you don’t press straight down you break the lead. Twist and push the bottle lid along the pencil (without spiking your fingers). Repeat for the second bottle lid and pencil.

Step 4: make the other two wheels
Place a bottle lid, open end down, on the Blu Tack. Make a hole and push it onto the pencil. Repeat for the final bottle lid.

Step 5: attach the bearings
Tape each bearing to the bottom of the base. Be careful not to crush the bearing.

Step 6: fit the axles
Take the wheel off the pointed end the pencil. Push the pencil through a bearing and refit the wheel. Be careful not to crush the end of the bearing. Twist the wheels apart slightly to leave a small gap between the wheels and bearings. Hold the buggy and spin the wheels to check the axles turn freely.

Step 7: attach the balloon
Slide the balloon over the end of the plastic tube and hold it on with the rubber band so it doesn’t fly off when you blow up the balloon. You might need to double the rubber band over a few times.

Step 8: attach the tube
You need to tape the tube to the top of the base. Make sure the end is sticking out so you can blow into it. If the tube is curved, like the garden hose, make sure the balloon end is curving upwards. This stops the balloon rubbing on the floor as much, so the buggy goes faster.

Test!
Now you can try out the buggy. Blow up the balloon through the hose. Hold the neck of the balloon, put the buggy on a smooth floor and let go.

What else can you do?
You can decorate the buggy or colour it in.
You can compare how the buggy moves on different surfaces, such as a smooth floor, carpet and tarmac. You can adapt the buggy to run better on rougher surfaces, for example by preventing the balloon from rubbing on the floor

The science behind the project:
When you blow up the balloon, you store energy in it, both in compressing the air in the balloon relative to the air outside it, and in stretching the balloon itself. This stored energy is called potential energy.

The potential energy is converted partly to kinetic energy as the buggy accelerates. When you let go of the blown-up balloon a jet of air is pushed out of the back of the tube. This acts the same way as the jet coming out of a rocket, which pushes the rocket forwards. This is a demonstration of Newton’s third law.

Friction acts to slow the buggy down. This is a force between two surfaces which move, or try to move, relative to one another. For example, the balloon rubbing on the floor is a source of friction. The axles turning in the bearings, or the wheels rubbing against the edge of the bearings are further sources of friction. In the end all the energy is converted by friction to heat and sound.

This project is taken from my book Technology for Fun . For more ideas you can visit my Technology for Fun website: www.technologyforfun.co.uk

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