Question

One end of a string of length $1.0m$ is tied to a body of mass $0.5kg$. It is whirled in a vertical circle with angular velocity $4rad/s$. The tension in the string when body is at the lower most point of its motion is equal to [Take $g=10m/s^2$].

• A. $3N$
• B. $5N$
• C. $8N$
• D. $13N$

Answer 1

The correct option is D $13N$

$T-mg=\frac{m{v}^2}{r}$

or, $T-mg=m{\omega }^{2}r$

$\therefore T=mg+m{\omega }^{2}r$

$=(0.5\times 10)+(0.5\times 4^2\times 1)$

$=5+8=13N$