Pressure

Pressure, is defined as P=F/A this in turn translates to pressure equals mass times acceleration divided by a surface area. in climbing the masses and acceleration are incredibly high for the total area. take the gentleman in the picture above for example he is essentially holding on with one hand. his feet are not touching the wall and his other hand is only helping him to balance, looking at size and build we can guess that he is about 160 pounds. Which in turn converts to about 73 kilograms.for our example we will say that acceleration due to gravity is 10 meters per second squared (instead of its actual 9.8m/s^2). we don't really have a way of telling the surface area that his hand covers so instead we will use an average for a male hand. this turns out to be about 12600 square mm which translates to approximately .0126 square meters. 

    So to get pressure we now just plug in the numbers, Pressure = 73kg x 10m/s^2 / 0.0126m^2 this comes out to be 57937 newtons per square meters. This number is fairly large, and in climbing it can get much larger. when you consider that all the pressure that is being put on the rock you have to think about what is translating back to the climbers joints, tendons and muscles. the stress that gets put on the joints is sometimes tremendous. this in turn causes some climbers to pop there pulley joints in there fingers or to rip right though the tendons in there arms. this is mostly known to happen when a climber is using a mono pocket (a very small hole in a rock surface that you can only fit one finger in) or when using very small crimps to stay on the wall.(crimps being hold that have almost nothing to hold onto, so you can only get the very tips of your fingers on them)  For instance lets say that our climber from earlier was supporting his weight on the use of one mono pocket. this is something that some climbers can do, although it is known to be quite hard. the only thing that changes from our original equation is the surface area, because now instead of supporting himself with one hand he is doing it with a single finger tip.  So we have  pressure = 73kg x 10m/s^2 / .00048 m^2 now the pressure that is caused by the climber onto the rock and in turn translates back to the climber is 1520833 newtons/m^2. hopefully you can see how large that is, and more importantly how important it is to think about pressure and such when you are climbing, it could help keep you from injury.