1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: More circular motion questions:

  1. Dec 29, 2011 #1
    these are only short queries so i put them in the same thread.

    1) one end of a light inelastic string of length a is attached to a fixed point A and a particle of mass m is attached to the other end,B. The particle is held at the same level as A,at a distance of asin x away from A,and released. find
    a) the impulse in the string when it becomes tau
    b) the speed of the particle immediately after the string becomes taut
    c) the cosine of the angle between the string and the vertical when the particle first comes to instantaneous rest.

    for the last part i can get the answer only if i know the particle goes above my PE=0 line which i chose to be at the point of the jerk. is this obviously the case?

    a particle P of mass 2m is attached by a light inextensible string of length a to a fixed point O and is also attached by another light inextensible string of length a to a small ring Q of mass 3m which can slide on a fixed smooth vertical wire passing through O. the particle P describes a horizontal circle with OP inclined at an angle 60 with the downward vertical.

    a) find the tensions
    b) show speed of P is (6ga)^1/2
    c) find the period of revolution of the system

    how do i find part c)? i have used v to find w (angular velocity) but this does not give me the book answer.the radius of the circle being travelled is art(3)/2 if it helps.
  2. jcsd
  3. Dec 31, 2011 #2
    anyone able to tell me how to find period?
  4. Jan 2, 2012 #3
    a sly bump as the thread asking how to find a in f=ma has had more replies :0

    surely someone can tell me how to find the period of the system given the speed of

    the answer,if it helps, is 2pi(a/6g)^1/2
  5. Jan 4, 2012 #4
    have been assured my answer is correct for question 2,book is wrong. i have only the last part of question 1. is there an obvious reason the particle goes aboive my pe=0 line?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook