First slide
Simple harmonic motion
Question

A pendulum of  length 1cm hangs from an inclined wall. Suppose that this pendulum is released at an initial angle of  10 and it bounces off the wall elastically when it reaches an angle of  5 as shown in the figure. (Take g=π2 m/s2) The period of this pendulum is (in second)

Moderate
Solution

In  right half of oscillation of bob it oscillates 10 so amplitude is  θ0=10°

In left half it undergoes only 5° due to the obstruction of wall. It travels only 5° that is θ02.
Using the equation for angular SHM  θ=θ0sinωt ……( 1 )
Time (t) to travel from 0 to  θ02,substituting θ=θ02 in equation ( 1 )
θ02=θ0sinωt
ωt=30
ω=2πT
t=T12
Simple harmonic oscillator takes  T12 seconds. So total time period of the oscillation is
T'=T4+T12+T4+T12=23T
where T=2πlg=2s
T'=23.2=43=1.33s
Therefore, the correct answer is 1.33
 

Get Instant Solutions
When in doubt download our app. Now available Google Play Store- Doubts App
Download Now
Doubts App