Question

A simple pendulum is executing simple harmonic motion with a time period T. If the length of the pendulum is increased by 21%, the increase in the time period of the pendulum of increased length is?

(a) 10%

(b) 30%

(c) 21%

(d) 50%

I had been asked this question in examination.

My question is from Wave Motion topic in division Waves of Engineering Physics I

Answer 1

Right answer is (a) 10%

For explanation I would say: As T is proportional to l, the percentage increase in a time period on increasing the length by 21%

=1/2×∆l/l×100=1/2×21=10.5%.