Question

find the Tension in string when the Bob makes 30° with the vertical​

Answer 1

Solution

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Correct option is C)

For simple pendulum,

∴T=

r

mv

2

+mgcosθ...(i)

2

1

mv

2

=(rcos30°−rsin30°)mg...(energy conservation)

r

mv

2

=2[

2

3

−

2

1

]mg=(

3

−1)mg

∴ Substituting

r

mv

2

in equation (i)

We get,

T=(

3

−1)mg+mg(

2

3

)

∵T=mg(

2

3

3

−1) Thus option C