Question

The effective length of a pendulum is 1m and the mass of its bob is 5√2×10^-3 kg. The bob is  drawn to a side until the string is horizontal and released. Find its velocity when the string  makes an angle 45 degree with the vertical.


plz plz plz do it in step by step.............​

Answer 1

Explanation:

Mass of the bob = 100 g = 0.1 kg.

Length of the String = 1 m.

Kinetic Energy = Potential Energy when the angle is 0°

therefore, K.E. = mgh

∴ K.E. = 0.1 × 9.8 × 1

K.E. = 0.98 J.

When the angle will be 30°, then the Vertical height will be hcos30°.

hcos30° = 1 × √3/2 = √3/2 m.

∴ K.E. = 0.1 × 9.8 √3/2

∴ K.E. = 0.98√3/2

∴ K.E. = 0.49√3 J.

Hope it helps.