Teach Kids About Friction, Smoothly!

I have found from experience that making kids understand the concept of friction is bit of a hard nut to crack though the concept is very simple and clear once understood properly so here is a way to make the concept of friction slip down smoothly through their throats.

Take the kids out to a park where we have the slides as shown in figure 1 below. Ask them one by one to climb on top of the slide via the stairs and make them skid. Of course they must have done this a dozen times before but this time it is with a perspective to learn the effects of friction. Calculate the time required for a child to skid down the entire slope from start to the end.

Now put a coase material such as a gunny bag under their butt and ask them to repeat the process of skidding down. You will notice that the time required to come down has increased to a certain extent

You can repeat the same experiment by pouring a water bucket on top of the slide and then noting that the time to slide down has decreased*

Lastly just place a board or something with rollers under the kids and watch them slide down faster than ever*

*However please note that the last two steps could be dangerous so only perform when at least two people are around the kid to hold him/her in case the speed is too fast

We will only consider two types of friction here for simplicity

• When an object slides over another it is the sliding friction which comes into play
• When an object rolls over another it is the rolling friction which comes into play

When you see an object that is very smooth and feels almost like silk to touch just examine it under a microscope. You will find that it is made up of irregular surfaces which might be very small for the eye to see. So when these irregular surfaces lock up against each other it requires a sufficient force to move them. Apart from that there are also forces of molecular adhesion which do not want objects to move apart and these forces have to be overcome in order to make objects move, hence the experience of friction.

I started off by suggesting an experiment and later on little bit of theory was explained and here is where they both meet

• When the kids were sliding down normally, it was a case of sliding friction
• When the kids were sliding upon water, it was still sliding friction but decreased due to lubricant (water in this case)
• When the kids were literally gliding down on roller boards, it was rolling friction

So the results from the experiment are

• friction is always present between two surfaces
• rolling friction is less than sliding friction
• lubricants decrease friction