Question

5. A pendulum consisting of a mass m = 0.2 kg attached to a massless rod of length L = 0.3 m is pulled to an angle θ = 15° and released. The speed of the mass at the bottom of the swing is
a) 0.742 m/s

b) 1.03 m/s

c) 0.254 m/s

d) 0.448 m/s

e) 0.595 m/s

Answer 1

Answer:

option D

Explanation:

given,

mass of pendulum = 0.2 Kg

length of rod = 0.3 m

angle of inclination = 15°

speed of mass at bottom = ?

using conservation of energy  

PE is converted into kinetic energy

$mgh = \dfrac{1}{2}mv^2$

h = L - L cos θ

h = 0.3 - 0.3 cos 15°

h = 0.0102 m

now,

$9.8\times 0.0102 = \dfrac{1}{2}\times v^2$

    v = √0.2

   v = 0.448

hence, the correct answer is option D