Every falling object will produce some force and it’s same with you falling of the route. Energy that will be produced is larger, lager the fall is. The piece of equipment that will absorb most of this force is your rope. More rope there is available to absorb the forces safer the fall will be.
This can be measured by using a ratio known as a fall factor. The fall factor is simply a distance fallen, divided by overall length of rope available to absorb the fall. Lower the factor, safer the fall is.
Fall distance isn’t important in this sometimes short falls can be much harder then long ones. The important is how much of this force is absorbed by rope. Climber falling for 2 meters with 10 meters of rope available will produce fall factor (2/10) 0.2 - soft fall .Climber falling 2 meters with 2 meters of rope available will produce fall factor (2/2)=1. Climber falling 4 meters with 2 meters of rope (no protection falling below the belayer) will produce fall factor (4/2)=2 this will be very hard fall. High fall factor falls are dangerous and could cause injury to climber.
In real world some force will be absorbed by a belayer and rope slipping through belay and by knots tightening . Remember that runners introduce friction and that will cause the fall factor to be larger than if rope was running completely free.
Climbing ropes are designed to limit the force of climbers weight (80Kg) in a worst case fall (Fall factor 2) to no more than 12kN thus rest of the gear can be designed to work with this known maximum force.