SHM Flashcards
What is the condition for SHM?
Acceleration is proportional to minus displacement.
What is the time period for SHM?
T, the time taken for one complete cycle. e.g max positive disp. to max negative disp. and back to max positive.
Explain an SHM pendulum system
in SHM if the angle to the vertical is small, as the small angle approx. can be used. T = 2pi root(l/g), T is time period, g is g and l is length of string. Forces at any point are obviously mgcos theta and mgsin theta.
Explain an SHM mass-spring system
F = -k x (k is spring constant, x is stretch). Time period is T = 2pi root(m/k). Can be set up horizontally or vertically.
Explain energy in SHM
With no damping, energy is constant; Et = Ep + Ek. All Ep at max disp, all Ek at minimum disp.
Explain damping in SHM
Process by which an oscillating object loses energy. Due to air resistance / friction etc. Light damping has oscillations and slowly reduces amp; heavy damping (overdamping) causes object to very slowly reach equilibrium with no osc; critical damping has the object reach equi quickly without osc.
What is the natural frequency of an object?
The frequency at which it would oscillate if left freely, with no driving/damping forces.
What is resonance?
The process that produces the maximum in the amp of a forced oscillation, when driving frequency = natural frequency.
How does damping affect resonance?
The lighter the damping the larger the max. amplitude at resonance, and the closer the resonant frequency is to the natural frequency. Higher damping reduces the frequency of the peak.
