Find the angle in radian though which a pendulum swings if its length is 75 cm and the tip describes an arc of length
(i) 10 cm (ii) 15 cm (iii) 21 cm

Solution:

Given that the length of the pendulum swings is 75 cm. ⇒ radius is 75 cm.

We know that, in a circle of radius r, the length of the arc is l that subtend at an angle θ radian at the centre, then θ = l / r radian

(i) l = 10 cm

⇒ θ = l / r radian

⇒ θ = 10 / 75 radian = 2/15 radian.

(ii) l = 15 cm

⇒ θ = l / r radian

⇒ θ = 15 / 75 radian = 1/5 radian.

(iii) l = 21 cm

⇒ θ = l / r radian

⇒ θ = 21 / 75 radian = 7/25 radian

NCERT Solutions Class 11 Maths Chapter 3 Exercise 3.1 Question 7

Find the angle in radian though which a pendulum swings if its length is 75 cm and the tip describes an arc of length. (i) 10 cm (ii) 15 cm (iii) 21 cm

Summary:

Thus, the angle in radian though which a pendulum swings are (i) 2/15 radian, (ii) 1/5 radian, and (iii) 7/25 radian