Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum Nov 29th 2009, 10:58 AM #1 Senior Member   Join Date: Sep 2009 Location: St. John's, NL Posts: 124 distance...? M, a solid cylinder (M=2.43 kg, R=0.115 m) pivots on a thin, fixed, frictionless bearing. A string wrapped around the cylinder pulls downward with a force F which equals the weight of a 0.670 kg mass, i.e., F = 6.573 N. Calculate the angular acceleration of the cylinder. If instead of the force F an actual mass m = 0.670 kg is hung from the string, find the angular acceleration of the cylinder. *********** How far does m travel downward between 0.550 s and 0.750 s after the motion begins? the problem i am having with is *********** How far does m travel downward between 0.550 s and 0.750 s after the motion begins? ***** this part of questions. i found first answer: 47.3 rad/s^2 second answer: 30.3 rad/s^2 and for the third one, i've tried d=(0.5)(a)(t)^2 at 0.550s d=(0.5)(a)(t)^2 =(0.5)(30.3)(0.550)^2 = 4.58 m at 0.750s d=(0.5)(a)(t)^2 =(0.5)(30.3)(0.750)^2 = 8.52 m and i subtracted them and got 3.94 m but its wrong i've tried -3.94 as well but wrong as well what did i do wrong?   Nov 29th 2009, 11:20 AM #2 Senior Member   Join Date: Sep 2009 Location: india Posts: 409 use a=r alpha ie a=.115*30.3 and then the formula s=1/2 a(t2^2-t1^2)=0.46 metres   Nov 30th 2009, 12:20 AM #3 Member   Join Date: Oct 2009 Posts: 58 To the first question : Calculate the Moment of Inertia of the cylinder , then the the Moment of the force ... So M=(I)(theta'') theta'' = M/I  Tags distance Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post Saloom Energy and Work 2 Apr 5th 2013 03:18 PM stealth Kinematics and Dynamics 5 Mar 13th 2010 10:47 AM juggalomike Advanced Mechanics 1 Jan 14th 2010 05:49 AM Book Periodic and Circular Motion 1 Dec 7th 2009 10:22 PM christina Kinematics and Dynamics 2 Oct 28th 2009 06:26 PM 