Question

Two point size bodies of same mass are knotted to a horizontal string one at the end, and the other at the mid point of it. The string is rotated in horizontal plane with the other end as centre. If T is tension in the string between centre of circles and first body then the tension in the string between the two bodies is

• A. $\frac{T}{2}$
• B. $2T$
• C. $\frac{2T}{3}$
• D. $\frac{3T}{2}$

Answer 1

The correct option is C $\frac{2T}{3}$

Let T' is tension in outer string and T is tension in inner string.

Now, from FBD of outer mass,

$T^{\prime }=m\ast 2L\ast {\omega }^2$

From FBD of inner mass,

$T-T^{\prime }=m\ast L\ast {\omega }^2$

$T=3mL{\omega }^2$

$T^{\prime }/T=2/3$

$T^{\prime }=2T/3$

Option C is correct.