15.6 Free,Damped and Forced Oscillations Flashcards
What is a free oscillation?
one in which no external forces would be acting on the oscillating body except the force that has given rise to the oscillation. This means the object oscillates at natural frequency and will do so forever due to conservation of charge.
Is a fully free oscillation possible?
Practically no. This is because it is impossible to remove resistive forces. Hence we often call oscillations in the air free oscillations
What is a damped oscillation?
one in which the energy is being transferred to the surroundings, resulting in oscillations of reduced amplitude and energy.
When the oscillation is damped is the principle of conservation of energy still upheld?
Yes, as energy is given to surroundings.
What happens when work is done against external forces by an oscillating body?
The energy is lost and so the oscillation dies away?
What can we do to avoid oscillation dying away if it is damped?
Provide a driving force.
Is frequency and period dependant on amplitude?
No, if amplitude is higher the oscillation willl get more speed to cover that distance in the same time slot
Why would systems be deliberately damped?
To stop or minimise effects of resonance.
What can damping vary from and to?
light to overdamping
Greater damping means what happens
The rate of decrease of amplitude is higher
What is critical damping?
Damping degree which stops oscillation fully in the shortest time possible.
What is critical damping used by?
Car suspensions
What is a process which is similar to damping?
Plastic deformation of ductile materials. This is because change of shape absorbs energy
What is a forced oscillation?
one that occurs if a force is continually or repeatedly applied to keep the oscillation going so that the system is made to oscillate at the frequency of the source and not at its natrual frequency.
What is a forced oscillation sometimes called?
the driving force
