Question

A light string is warped round a cylindrical log of wood which is placed on a horizontal surface with its axis vertical an it is pulled with a constant force $F$ as shown in the figure. (Friction is absent everywhere)

• A. Tension $T$ in the string increases with increase in $\theta$
• B. Tension $T$ in the string decreases with increase in $\theta$
• C. Tension $T>F$ if $\theta >\pi /3$
• D. Tension $T>F$ if $\theta >\pi /4$

Answer 1

The correct option is A Tension $T$ in the string increases with increase in $\theta$

$F=2Tcos\theta$

As $\theta$ increases,$cos\theta$ decreases and therefore T increases