I am trying to work out the efficiency for a self built acrylic bow, but I am having some problems working out a predicted height my arrow will reach. For the experiment i fired the arrow into the air and recorded the height it travelled, I have also recorded the weight of the arrow and the force applied to the sting when firing the arrow. I then proceeded to do this for ten set forces 1N- 10N recording the results, after recording the results i worked out a way in which I could convert the area under a force extension graph into kinetic energy and then into GPE. Once I had the GPE I would divide the total by gravity and then by the mass of the arrow, giving me a predicted height. To work out the height the arrow would travel, I measured the distance the arrow travelled for each of my forces; I then drew a force extension graph, using my method I worked out that 2N my bow was 262% efficient and for 9N my bow was 0.8% efficient. A table of my results has been uploaded I worked out the predicted height by using this chain of thought Displacement under the graph = Kinetic Energy Kinetic Energy = Gravitational potential energy Gravitational potential energy / Mass and gravity I don’t think I am working out the predicted height correctly but I cant think of another way to do it, all help welcome.