Question

A stone of mass 100 g is suspended from the end of a weightless string of length 1 m and is allowed to swing in a vertical plane.The speed of the mass is $2m{s}^{-1}$ when the string makes an angle of ${60}^o$ with the vertical .Calculate the tension in the string at $\theta$=${60}^o$.

• A. 2.89 N
• B. 89.9 N
• C. 0.89 N
• D. none of these

Answer 1

The correct option is C 0.89 N

$\begin{array}{c}\text{let, tension}=T\\ V=2m/s^2\\ \text{Tension in the String will be}\\ T=\frac{m{v}^2}{\gamma }+mq\cos {60}^{\circ }\\ =\frac{100}{1000}(\frac{4}{1}+9.8\times 1/2)\\ =0.89N\end{array}$

Ans. Option C