Question

A pendulum swings through an angle of 30∘ and describes an arc 8.8 cm in length. Find the length of the pendulum in cm.

Options

• 16.8

• 17.3

• 15.1

• 14.5

Answer 1

16.8

Explanation:

Let r be the length of the pendulum

Length of arc = 8.8 cm

∠AOB = 30^∘

Length of an arc of a sector of an angle `theta = (theta/360) xx 2 pi "r"`

Length of arc `= theta/360 xx 2 pi r = 8.8`

`= (30/360) xx 2 xx (22/7) xx "r"`

`"r" = (8.8 xx 21)/11 = 16.8  "cm"`