Transcript Document

External Forcing
SHO with an additional external force
Why this particular type of force?
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Fourier Series
For any arbitrary time varying force
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Solution using Fourier Series
Find solution for a single frequency
Superpose solutions
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
The equation
where
Solution=Complementary Function +
Particular Integral
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Particular Integral
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Amplitude and Phase
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Amplitude and Phase
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Low Frequency Response
Stiffness Controlled Regime
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
High Frequency Response
Mass Controlled Regime solution of
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Effect of Damping
Solution=Complementary Function +
Particular Integral
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Solutions
Complementary Functions are transients
Steady State behaviour is decided by the
Particular Integral
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Solution with Damping
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Amplitude and Phase (again)
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Amplitude and Phase (again)
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/
Some Key Points
High frequency and low frequency
behaviour unchanged by damping
Amplitude is finite throughout
Maximum Amplitude at
 Somnath Bharadwaj and Pratik Khastgir, Department of Physics and Meteorology, IIT Kharagpur, 721 302 India
http://www.cts.iitkgp.ernet.in/~phy1/