Liidlii Kue/Fort Simpson - Students applied their scientific knowledge to everyday questions at the Bompas elementary school's science fair last week.

Alex Keefe prepares to launch a toy car using the trebuchet he constructed for his Bompas elementary school science fair project. - Roxanna Thompson/NNSL photo

On Nov. 21 students put their projects on display in the school's gym and invited the public in to learn more about a wide range of topics.

For Alicia Norris the idea for her project was created when her father started looking under the hood of the family vehicle.

"My dad wanted to change his summer oil to winter oil so I wondered why you had to do this," she said.

The question launched Norris on a scientific investigation to find out if temperature affects the viscosity of engine oil.

To test her theory that temperature does have an effect, she started with three different oil grades - 0W, 5W and 10W. With the oil at room temperature, Norris poured a measuring spoon full of each on a ramp and timed how long it took for the oil to flow to a set mark on the ramp. Next the three bottles of oil were stored in a freezer to cool the oil and the experiment was conducted again.

The results of the experiments have given Norris the knowledge needed to give people advice on their oil choices. For winter conditions Norris recommends 0W-30 because it's a thin oil. Summer driving requires something thicker like a 10W-30. The project won Norris first place in the Class 6 competition and was worth the effort, she said.

"I found it really interesting and it was really fun to do," said Norris.

"I learned a lot of new things."

Taking second place in Class 6 was another father-inspired project.

Watching her dad put plaster on the walls of their house in preparation for painting gave Katrina Browning the idea to test what type of reinforcement works best in plaster.

Using straightened paper-clips as reinforcement bars, Browning experimented on which length of paper-clip provides the most support for cylinders of plaster cast in paper towel tubes.

Browning thought full-sized paper-clips would provide the most support, but discovered otherwise. The cylinder reinforced with paper-clips cut into thirds supported the most weight at 31 pounds.

"I was really surprised," she said.

Also coming out of Class 6 was a project with a historic focus. For Alex Keefe the burning scientific question was how to build the best possible trebuchet.

Trebuchets are siege engines dating back to the Middle Ages that are used to throw projectiles at, or over walls. Keefe became interested in the war machines after seeing a life-size one in England throw a burning projectile during a family vacation.

"It's really interesting because I saw a real one," said Keefe.

Working on a smaller scale, Keefe started by building a model out of Lego that could launch Lego bricks. A second wooden model was built with the help of his father.

After trying a number of different design variations, Keefe is confident he has worked out the bugs in the models.

Keefe's advice for would-be siege parties is to build trebuchets with a shortened throwing arm and a heavy counter-weight.