Session 3: How can we change the friction force

Session 3: How can we change the friction force – Step 2 Scientific approach

Objective : Experiments with a scientific approach to the modification of area resisting motion.

Explanation

Material

Cars
Criteria to choose the cars: the car should not be to light, otherwise they are instable, but they should not be to heavy, because they should roll quite far when you push them.
After, trying different cars in common toy shops, we arrive to the conclusion that the best cars are the one’s designed for babies (18 mth), since they are not very strong and not very accurate in general those car are rolling well
Car ramp, simple slope
Either you build it yourself, either you take kids car ramp, the main point of a good ramp, is the fact that the passage between the floor and the ramp should be as smooth as possible, this is why most of the time the one you can by are thin and curced
Sheets of paper
Straws
Adhesive paper

Maximum duration

45 minutes

Main question to be asked

Introduction/Starters

Discuss with your students what happened in the previous session and how you are going to organise this one.

Main activities

Test with your students if the launching system of the car is reproducible, because they 6have to launch several times their car and measure the travelled distance.
Then propose they can start their first parameter for example with a simple square. They can measure the travelled distance, and then double the square area and measure again.
Then they can also take difference shapes, e.g. square, rectangle and circle, and perform the test with exactly the same surface but for different shape.
They can try a volume built in paper, to avoid increasing too much the weight of the car, and building a cylinder or using a ping-pong ball.

Mathematical aspects: again depending of the mathematical progress of your students, you can perform several mathematical exercises, to compare areas. You can either do it geometrically by folding a piece of paper if they are young (this works for triangles, squares and rectangles) of if they are older they can apply the formulae they have learnt.