A block of 3 kg is attached to a string whose other end is attached...

A block of $\sqrt{3}kg$ is attached to a string whose other end is attached to the wall. An unknown force $F$ is applied so that the string makes an angle of $30 °$ with the wall. The tension $T$ is : (Given g $= 10m{s}^{– 2}$ )

A block of 3 kg is attached to a string whose other end is attached to the wall. An unknown force F is applied so that

Options

A $20N$
B $25N$
C $10N$
D $15N$

Correct answer

A. $20N$

Step-by-step solution

A block of 3 kg is attached to a string whose other end is attached to the wall. An unknown force F is applied so that

From geometry, $\theta = 30 °$ .

For equilibrium,

Tcos\theta = mg $</p><p>$ ⇒ T = \dfrac{mg}{\cos 30 °} ⇒ T = \dfrac{\sqrt{3} \times 10}{\dfrac{\sqrt{3}}{2}} $</p><p>$ ⇒ T = 20N

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