Friction can be a car's best friend on a slippery road. If the road is too slippery the tyres slide or skid. Local authorities monitor roads to make sure they are not too slippery. They measure the friction between the road surface and the car, and the information is sent to the local county council who will fix the road if necessary.
After watching this clip students could be asked to describe in their own words what friction is, noting that friction is a force which exists between objects moving across a surface and opposes motion. Students could be asked to bring in their sports shoes or trainers, and to consider what physical characteristics a trainer needs to be effective. With trainers do we want a lot of friction or as little as possible? Students could consider that they need to make quick turns on the surfaces on which they play sports. They could then look at their trainers and consider how they have been designed to achieve this desired level of friction, with particular focus on the tread of the shoes.
Students could then conduct an experiment to test their trainer on a range of different surfaces. As a class, students could decide upon four or five floor surfaces for example; grass, tile, carpet, polished wood, concrete or gravel. Challenge students could then predict which surface the trainer will move along most smoothly and easily, which will require least force to move the trainer, noting that the more the force required the more friction present. Students could then use a forcemeter to test their predictions, recording their results and then analysing the data.
Using two wooden blocks the same size students should chose from a range of materials e.g. cling film, sandpaper, cotton, satin and cover one block with a material that will cause the least friction and the other with material that will cause the most friction. They could then visit a local park to test their predictions by sliding the blocks down the slide. They should record their results and share them with the class.