Along and across the grain of wood
Once trees have been cut into logs - they are then cut into ‘planks’ of wood, as shown.
Wood is much stronger in 1 direction, than it is in the other (opposite) direction. It is the direction of “the grain” which provides and determines the strength across the grain.
Which of these 2 scaffold-boards do you think will be stronger: 1 or 2?.
Which of these 2 arrangements do you think a karate expert
would find it easier
Many years ago trees used to be "chopped- down".
Why do you think saws were used