A bob hangs from a rigid support by an inextensible string of length - If it is displaced through a distance - from the lowest position keeping the string straight- then released- The speed of the bob at the lowest position is-

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Standard XII

Physics

Springs in Parallel and Series

A bob hangs f...

Question

A bob hangs from a rigid support by an inextensible string of length $ℓ$ . If it is displaced through a distance $ℓ$ (from the lowest position) keeping the string straight, & then released. The speed of the bob at the lowest position is:

\sqrt{g ℓ}

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\sqrt{3 g ℓ}

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\sqrt{2 g ℓ}

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\sqrt{5 g ℓ}

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Solution

The correct option is B $\sqrt{g ℓ}$
Distance= $l$
change in height= $l c o s 60 = l / 2$

From energy conservation,
PE at max height= KE at lowest point= $m g l / 2 = m v^{2} / 2$
$v = \sqrt{g l}$

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A bob hangs from a rigid support by an inextensible string of length ℓ. If it is displaced through a distance ℓ (from the lowest position) keeping the string straight, & then released. The speed of the bob at the lowest position is:

The correct option is B √gℓDistance= lchange in height= lcos60=l/2From energy conservation, PE at max height= KE at lowest point= mgl/2=mv2/2v=√gl

A bob hangs from a rigid support by an inextensible string of length $ℓ$ . If it is displaced through a distance $ℓ$ (from the lowest position) keeping the string straight, & then released. The speed of the bob at the lowest position is:

The correct option is B $\sqrt{g ℓ}$
Distance= $l$
change in height= $l c o s 60 = l / 2$

From energy conservation,
PE at max height= KE at lowest point= $m g l / 2 = m v^{2} / 2$
$v = \sqrt{g l}$