Hi all, first time posting so lets see how it goes! My problems are with a piece of physics coursework I'm doing for my A-level courses. I chose to investigate the 'torque effect' on single propeller planes. (If you are unsure of what this is, its basically newtons third law, reasoning that when a plane makes a propeller spin, the propeller makes the plane spin). So i need a way to calculate torque so i can compare it to forces produced on the plane. The setup i used for the experiment is show in the picture: [PLAIN]http://img827.imageshack.us/img827/1451/physicsforum1.png [Broken] Basically, its a suspended mock up of a plane, with a propeller on the front. I'm using a tachometer to measure rpm and scales to measure the 'weight' induced on the wing, which i could convert into a moment. How can i find the torque of the propeller from this? I've spent ages trawling the internet. The variables i know are: rpm, length and mass of propeller. I also changed the distance alone the 'wings' of the mockup which i measured the force from, using the scales to measure the 'force' the torque effect applied on them. So what i understand, is: ω = 2*(pi)*f a_tangential = Angular acceleration*R τ = I*α But how do i link angular frequency with angular acceleration. How could i do this? Could i just use the ideas in the picture and trigonometry? [URL]http://upload.wikimedia.org/wikipedia/commons/5/56/Acceleration.JPG[/URL] Many thanks to all!!