How often has junior wanted to test his strength against his father.
Father of course plays the game and pretends to be weak enough for junior to lose with dignity! Most sports try to equalise performance by handicapping the better player and so we decided to find ways of doing this in trials of strength between father and son, or grandfather and grandson as the case may be.
The principle is well-known in engineering as mechanical advantage.
The pulley systems on sailing boats use this to provide greater force to the sailing rig than is possible by hand alone.
So is it possible to use a pulley system to make a tug of war that equalizes the strength of father and son? A simple pulley will offer an advantage of two to one.
A rope tied to the block of the pulley is pulled by father.
Another rope is tied to a fixed object such as a tree and then round the pulley wheel to the child.
This gives the child twice his actual strength.
This arrangement can again be doubled to give junior four times his strength by using two pulleys.
In this case the second pulley is attached as though it is the father and the two ends of the rope are attached to the tree.
It is possible to buy double pulleys that four times the advantage by doubling each time.
An alternative to the pulley is the lever.
The easiest example is a door where father pushes the door near the hinge while junior has the advantage of more leverage by pushing near the handle.
Various arrangements are possible by using a pole which is tied to a tree, either in the centre or at one end.
In the first case the participants will be on the same side of the pole, and in the second on the opposite side.
The strength needed can be varied by father pushing nearer the centre so that junior has greater leverage, this is easier to organise when the pole is held at one end so that there is more length and you are on opposite sides of the pole so there is more room.
There is the problem of finding a pole which is strong enough to cope with the force of two energetic people.
We tried it with a plank, we thought it would be stronger and less liable to break.
Rather than a tug-of-war perhaps these arrangements should be called a push-of-war!