Kinematics Question 555
Question: A stone of mass M is tied to a string and it’s moved in a vertical circle of radius r making n revolutions per minute.The total tension in the string when the stone is at it’s lowest point is [Kerala (Engg.) 2001]
Options:
A) $ mg $
B)$ m(g+\pi nr^{2}) $
C) $ m(g+\pi nr) $
D)$ m{g+({{\pi }^{2}}n^{2}r)/900} $
Show Answer
Answer:
Correct Answer: D
Solution:
$ T=mg+m{{\omega }^{2}}r=m{g+4{{\pi }^{2}}n^{2}r} $
$ =m{ g+( 4{{\pi }^{2}}{{( \frac{n}{60} )}^{2}}r ) }=m{ g+( \frac{{{\pi }^{2}}n^{2}r}{900} ) } $
