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
We know that in a circle of radius r unit, if an arc of length / unit subtends an angle θ radian at the centre, then .
\(θ=\frac{i}{r}\)
It is given that r = 75 cm
(i) Here, l = 10 cm
\(θ=\frac{10}{75}\,radian=\frac{2}{15}\,radian\)
(ii) Here, l = 15 cm
\(θ=\frac{15}{75}\,radian=\frac{1}{5}\,radian\)
(iii) Here, l = 21 cm
\(θ=\frac{21}{75}\,radian=\frac{7}{25}\,radian\)