Question

A conical pendulum of length $120cm$ moves making an angle of ${16}^o$ with the vertical. What is the period of circular motion of the bob? (in $s$)

$g=9.8m/s^2$

• A. $2.14$
  
• B. $2.96$
  
• C. $2.23$
  
• D. $2.155$
  

Answer 1

The correct option is D $2.155$

lenght of string l=120cm=1.2m
The time period of pendulum is given by $T=2\pi \sqrt{\left(\frac{lcosQ}{g}\right)}$
$T=2\pi \sqrt{\left(\frac{1.2cos{16}^0}{9.8}\right)}=2.155s$