Welcome to the Open Kiasa University. For today’s lesson you will need:

1 x Soapbox car
1 x Seventy year old pensioner
1 x Teenager of the same size and weight as the pensioner
1 x Adjustable slope of considerable length

Step 1. Place the teenager in the soapbox car and allow multiple runs down the slope, adjusting the slope each time until you have compensated for friction and the soapbox car runs at very close to a constant speed.

Step 2. Replace the teenager in the soapbox car with the pensioner of equal size and weight.

Step 3. Conduct multiple run down the slope, and observe as the soapbox car begins to slow down on the slope with each run.

Indeed, given a slope of sufficient length, it has been shown that not only does the soapbox car slow down on the frictionless slope, but that it will eventually come to a complete standstill. Further experimentation is required to prove the corollary to this rule that the soapbox car will in fact begin to rise back up the slope.

I don’t know how pensioners do it, I really don’t, and believe me I’ve tried to figure it out. I’m following one in my car and each slope we go down I end up catching them up and having to break. They’re not touching their breaks, unless every pensioner in England happens to have broken tail lights; I’m assuming through sheer good will that they’re not pulling with both hands on the hand brake, and anyway one would expect more tire squeal and smoke to be evident; and having tried heavy engine breaking myself, I can only assume that if they are indeed engine breaking that they’ve somehow managed to get their 1.1 litre hatchback into first gear while doing forty miles an hour, and the poor car is redlining it’s way down the hill, with various bearings disintegrating and the drivetrain threatening to launch itself out through the boot in protest.