Hypothesis: I think the car will go about 17cm because it is quite heavy in balloon car terms.
1. Take a lego chassis, add lego pieces and wheels to make a car.
2. Tape the straw to the balloon.
3. Fasten onto the chassis of the car with blue tac.
4. Blow into the straw for 5 seconds.
5. Calculate the distance travelled by the car.
6. Repeat steps 4-5 four more times.
Test 1: 28.5cm
Test 2: 31.5cm
Test 3: 33.5cm
Test 5: 19.2
Here is the graph of results for the Balloon Car
The average distance is 24.2cm. It is best to use lightweight materials and not to blow up the balloons too big because then there is too much friction and it won't travel as far.