Room 11 – ‘Physical Forces’
Room 11 has been integrating the investigation of physical forces in Science with design technology. Over two lessons our task was to investigate a way to use air to create a thrust force in order to increase the speed of model cars.
We set about constructing our cars by using equipment on hand, including cardboard, plastic wheels, wooden skewers and tape. We worked out how we could use straws and a balloon to create a thrust force and how to attach the apparatus to our car. Using a stopwatch, we timed how long it took for our model cars to travel one metre and we completed the test 3 times, recording the information in our booklet.
Our next step was to decide on some variables that we could change to improve the speed of our cars. To make it a fair test we could only change one variable at a time. We predicted what would happen before we tested each variable. We reflected on what worked and what didn’t work and the reasons why.
Tyler, Billy and Liam’s group changed the shape of the car from rectangular to triangular to create aerodynamics. Tyler said, “We noticed the car wasn’t moving and there was air leaking out of the straw, so we taped it up and it worked. The balloon was causing friction so we put skewers in to hold the balloon away from the wheels and it flew to the end for the first time!”
Riiana discovered the more her group’s balloon was inflated the slower the car actually went as it created a drag. Her team- mate Junsei made the following observations, “When we first made the car the base was really big and there were bits that we didn’t need. On the next design we took the left over cardboard off. On the third design we decided to make the base lower. Then we blew the balloon up to medium size and it went as usual. Then we blew it up to full size and the drag held it back. When we blew it up to just smaller than medium sized it went really fast!”
Alex, Toby and Luella predicted that cutting the straw smaller would allow the air to come out quicker and so the car would move faster. Mackenzie thought her group’s car would go faster with smaller wheels. Louis predicted that making the wheels smoother would reduce friction. Miles, Liam, Alannah and Stella decided to change the terrain that their car was tested on from rough (carpet) to smooth (hard surface). Alannah thought that if the car was smaller it would move faster.
Oliver S said that the whole process of constructing the model car and testing the variables was fun but there were some moments that did not go well. It was a fun experience that he would like to do again!