Question

Could you please provide an accurate answer for the following question. Please only answer if you are 100% certain you can solve it correctly. I will leave feedback that matches the effort and quality of your response. Thank you.

This is a vibrations question. Th image below shows a bifilar pendulum. The length of the strings is given as H. The length of the rod is given as 2H. There is a mass (which is idendical to the rod mass) located in the centre of the rod as a point mass. When the bifilar pendulum swings it has 3 modes. 4 H 2H i. What are the 3 modes? Why are only 2 of the 3 modes important?

Answer 1

periodic time DOMS" Page No. Angular displacement Angular accelerat Date Ho tp = 21 40 tp=2 / 012 tp-a 27 K2 GH no. of oscillath Ep 9H alik v 1 n = NOH RTK H =H2 pendulum, d. The equation of a bar, can be written according to If both angles are small ten = ptylo do HO (2H) o $=0 The restoring force at the point of attachment of the thread Band B1 will be Mg spada Mgo (forsmall o) dicular vertical

DOM5 Page No. Date / 41 since o= do the restoring force- Mg do 22 and restoring couple Mad do al Given on equation of motion IP --M9d20 40 0 + Mad²o 4I0 T= att 4 Il . The motion is SH.M. of periodic time Mad² T= 21 4 mk²4 The acc H Mg4H2 To 2TK VgH Three modes of Swinging of biftar perdum Swinging in a co-plane of the strings and the bar is called Mode 1 Swinging in a vertical plane perpandicular to bar is prodea. mode 3 is torsional oscillation about vertical axis att wi

DOM5 Page No. Page No. Date because of at one mode rod /pendum pendulum rotate in rolling motion So it will not effect So 2 out of 3 modes important