A block of uniform mass M = 2.5 kg is at rest on a table. A disk of mass 2M, radius R = 60 cm and of the same height as the block, which is initially spinning about its axis with angular speed w = 3.5 rad/s, is placed on the table such that it touches the block.The block-disc system thus starts moving such that they are in contact throughout the motion.
a) What is the initial accelaration of the block-disc system?b) Determine the instants of time t* and t(tot) when pure rolling starts, and when the block comes to rest, respectively.
Friction between the disk and the block may be ignored, and coefficient of friction (static as well as kinetic) at all other surfaces of contact is µ = 0.3. Take acc. due to gravity to be g = 10 m/s^2.
You may check your answer at the judge in the format "5,4,6" if your answer for part a is 5 m/s^2, t*=4 deciseconds and t(tot)=6 deciseconds.
This comment has been removed by the author.
ReplyDelete@mayank, yar please don't post the answer so soon(post it only if u r getting a wrong answer or u want a confirmation}
ReplyDeletei'm getting same
but, i have a doubt::
w = 3.5 "Hz", -- i don't think its right to give 'Hz' as unit of ang. velocity.. we shud multiply by 2(pi)..
i also have confusion in the last part,
ReplyDeletei'll give my method( and doubt) after sometime
yes right, we cant use hertz for angular frequency or angular velocity
ReplyDeleteOk ok.. we'll take radian per second instead of hertz then..
ReplyDelete(:
someone please help me in the 3rd part..i got 1st and 2nd..
ReplyDeletejust keep in mind that when pure rolling starts the friction and normal reaction by block on disk changes
ReplyDelete