SpaceLight

Presently, two things I need clarity on, please. Thing 1: I found this on youtube I organized it in the following and hope it's good for arriving at fair approximations of torque and rpm... T = I x alpha = F x r x sin(theta): By example... A rotor Mass of 100 kg, 'r' of 2 meters, A force of 75 Newtons, point of force at a 90 degree angle. First filling in T = F x r x sin(theta), as such: T = 75 N x 2 m x sin(90) = 150 N*m T = 150 N*m Next, add the other part of the equation, T = I x alpha; I = 1/2Mr^2, hence: T = 150 N*m = 1/2M x r^2 x alpha Resolved progressively... T = 150 N*m = 50 kg x 2^2 x alpha T = 150 N*m = 50 kg x 4 x alpha T = 150 N*m = 200 x alpha Next, for alpha: alpha = 150 divided by 200 = .75 rad/s^2 Next, convert .75 rad/s^2 to RPM using this equation: ([rad/s]/6.28318530718) x 60 = RPM (Note: 6.28318530718 was Pi x 2, I just filled it in....) Solved progressively... ([.75 rad/s]/6.28318530718) x 60 = RPM .11936620731891365 x 60 = RPM .11936620731891365 x 60 = 7.161972439134819 RPM .75 rad/s^2 = 7.161972439134819 RPM Correct? Thing 2: Please refer to attachment "thing 2". The only known variables: 1) One angle (at the location depicted in the diagram). 2) Distance between A & B. Objective: Find line 3 (the dotted line) given the two known variables; line 3 needs to be perpendicular to line 2. Note: The one known angle is not 90 degrees. If you could write the solution out simply enough with an example, that would be helpful. Sincerely grateful for your guidance. Thing2.bmp