Kinematics Question 767
Question: A ball of mass 0.1 Kg. it’s whirled in a horizontal circle of radius 1 m. by means of a string at an initial speed of 10 R.P.M.Keeping the radius constant, the tension in the string is reduced to one quarter of it’s initial value.The new speed is[MP PMT 2001]
Options:
A) 5 r.p.m.
B)10 r.p.m.
C) 20 r.p.m.
D) 14 r.p.m.
Show Answer
Answer:
Correct Answer: A
Solution:
$ T=m{{\omega }^{2}}r $
therefore $ \omega \propto \sqrt{T} $ $ \frac{{\omega _{2}}}{{\omega _{1}}}=\sqrt{\frac{1}{4}}\Rightarrow {\omega _{2}}=\frac{{\omega _{1}}}{2}=5rpm $
