Question

A simple pendulum is oscillating with an angular amplitude ${60}^0$ . If mass of bob is $50g$, the tension in the string at mean position is:

Consider: $g=10m{s}^{-2}$, length of the string, $L=1m$.

• A. $0.5N$
• B. $1N$
• C. $1.5N$
• D. $2N$

Answer 1

Answer: (B)

$1N$

Apply work energy theorem between A and B
$mgL(1-cos\theta )=\frac{1}{2}m{v}^2$

$10\times 1\times (1-\frac{1}{2})=\frac{1}{2}m{v}^2$

$v^2=10$

Then, the tension in, $T=mg+\frac{m{v}^2}{R}$

$=\frac{50\times 10}{1000}+\frac{50}{1000}\times \frac{10}{1}$

$=1N$