Term

Definition
One full cycle of motion is from maximum height at one side to maximum height on the other side then back to the first side. 


Term
LOWEST POINT OF AN OSCILLATION 

Definition
Is the equilibrium point; in motion the object is said to oscillate about equilibrium 


Term
DISPLACEMENT OF THE OBJECT 

Definition
From equilibrium changes during motion: decreases as returns to equilibrium; reverses and increases moving away from equilibrium in opposite direction; decreases as it returns to equilibrium; increases as it moves away from equilibrium towards starting position 


Term

Definition
Maximum displacement of the oscillating object from equilibrium 


Term

Definition
Constant amplitude with no frictional forces 


Term

Definition
Time for one complete cycle of oscillations 


Term

Definition
Number of cycles per second 


Term

Definition


Term

Definition
If two things do not oscillate correspondingly they have a phase difference because they are not in phase.
Phase difference in radians = 2∏♦t / T 


Term
PHASE DIFFERENCE IN DEGREES 

Definition
2∏ radians = 360º
so phase difference = 360 x ♦t / T 


Term
PRINCIPLES OF SIMPLE HARMONIC MOTION 

Definition
Oscillating objects speed up as it returns to equilibrium; slows down when it moves away from equilibrium 


Term
VARIATION OF VELOCITY WITH TIME 

Definition
Gradient of the displacement time graph 


Term
WHEN IS VELOCITY GREATEST? 

Definition
When gradient of displacement time graph is greatest; at zero displacement 


Term
VARIATION OF ACCELERATION WITH TIME 

Definition
Gradient of velocity time graph 


Term
WHEN IS ACCELERATION GREATEST? 

Definition
When gradient of velocity time graph is greatest so when velocity is zero and displacement is maximum in opposite direction 


Term
WHEN IS ACCELERATION ZERO? 

Definition
When displacement is zero. When gradient of velocity time graph is zero 


Term
ACCELERTATION AND DISPLACEMENT 

Definition
Acceleration is always in the opposite direction to the displacement (opposite signs) 


Term

Definition
The oscillating motion in which the acceleration is proportional to the displacement and always in the opposite direction to the displacement
acceleration = constant x displacement
a = (2∏f)^{2}x 


Term
WITH SINE AND CO SINE CURVES 

Definition


Term

Definition
Resulting force acting toward the equilibrium position ALWAYS 


Term
RESTORING FORCE, ACCELERATION AND DISPLACEMENT 

Definition
If the restoring force is proportional to the displacement to equilibrium, acceleration will also be equal to displacement (always towards equilibrium) THE OBJECT OSCIALLATES WITH SIMPLE HARMONIC MOTION 


Term
TWO STRETCHED SPRINGS AND A TROLLEY 

Definition
Half cycel can be recorded using a ticker tape attatched to one end of the trolley. When trolley is released, the ticker timer prints dots on the tape at 50 dots per second.
Graph of displacement against time can be plotted which can measure time period
Motion sensor linked to computer can record osciallting motion 


Term
CHANGING THE FREQUENCY OF THE OSCILLATIONS OF A LOADED SPRING 

Definition
Adding extra mass  increases interia; at certain displacement trolley would be slower without extra mass. INCREASING TIME FOR EACH CYCLE
Weaker springs  Restoring force would be less at any given displacement , so INCREASES TIME FOR EACH CYCLE OF OSCILLATION 


Term

Definition
An object oscillates with a constant amplitude because there is no friction force acting on it.
Only forces acting on it combine to form the restoring force.
If friction was present, the amplitude of oscillations would gradually decrease and stop
Friciton is usually present even if you can't see the change in amplitude after one cycle 


Term

Definition
At maximum displacement, velocity is 0 so potential energy is at it's maximum and kinetic energy is 0
At 0 displacement, velocity is at it's maximum so potential energy is 0 and kinetic energy is maximum 


Term

Definition
Total energy of system remains constant and equal to maximum potential energy 


Term

Definition


Term

Definition
When dissipative forces are present 


Term

Definition
Dissipate the energy of the system to the surroundings as thermal energy. 


Term

Definition
Time period is independent of amplitude.
Each cycle takes the same length of time as the oscillations die
Amplitude gradually decreases reducing by the same fraction each cycle. 


Term

Definition
Just enough to stop the system oscillating after it has been displaced and released from equilibrium.
Oscillating object returns to equilibrium in shortest possible time without over shooting. Important in mass spring systems such as vehicle suspension. 


Term

Definition
Damping is so strong that the displaced object returns to equilibrium much more slowly than if it critically damped. No oscillating motion occurs. e.g mass on a spring in thick oil. 


Term

Definition
A coiled spring near each wheel, between wheel axle and car chassis. When wheel is jolted , the srping smoothes out the force on the jolts. The oil damper fitted with each spring prevents the chassis from bouncing up and down too much. Flow of oil through valves in the piston of each damper provides frictional force that damps oscillating motion. Dampers ensure chassis returns to equilibrium in the shortest possible time  so close to critical damping 


Term

Definition
E.g pushing someone on a swing 


Term

Definition
Pushes on a swing are an example.
Force that varies regularly in magnitude with a definate time period 


Term

Definition
When a system oscillates without a periodic force being applied to it 


Term
AS APPLIED FREQUENCY REACHES NATURAL FRQUENCY OF THE MASS  SPRING SYSTEM 

Definition
The amplitude of oscillations of the objects increase more and more
Phase difference between the displacement and periodic force increases from zero to 1/2∏ at the natural frequency 


Term

Definition
Applied frequency is equal to natural frequency of mass spring system
Amplitude of oscillations become very large; lighter the damping, the larger the amplitude becomes
Phase difference between displacement and the periodic force is 1/2∏
Periodic force is in phase with the velocity of the oscillating object. 


Term
APPLIED FRQUENCY GREATER THAN NATURAL FREQUENCY 

Definition
Amplitude of oscillations decrease more and more
Phase difference between displacement and periodic force increases from 1/2∏ until it is ∏ out of phase with the periodic force. 


Term
WHEN IS THE AMPLITUDE GREATEST 

Definition
When applied frequency is equal to natural frequency providing damping is light
here:
applied frequency of periodic force =
natural frequency of a system 


Term
OSCILLATING SYSTEM WITH LITTLE OR NO DAMPING AT RESONANCE 

Definition
Applied frequency of periodic force = natural frequency of system 


Term

Definition
The periodic force acts on the object at the same point in each cycle causing the amplitude to increase to a maximum value limited only by damping.
Max amplitude, energy supplied by periodic force is lost at the same rate because of the effects of damping 


Term
APPLIED FREQUENCY AT RESONANCE 

Definition
Resonant frequency = natural frequency when there is little/no damping
The lighter the damping, the closer the resonant frequency to natural
Resonance occurs at a slightly lower frequency than natural 


Term
PENDULUMS OF THE SAME LENGTH 

Definition
If one pendulum is displaced, the other of the same length is forced to oscillate too and responds much more than if it were at any other length. It has the same time period so same natural frequency so oscillate in resonance. Response of other lengths depends on how close they are to initial pendulum. 


Term

Definition
If wind speed means the periodic force is equal to natural frequency, resonance can occur in absence of damping
e.g collapse bridge 


Term
STEADY TRAIL OF PEOPLE ON A BRIDGE


Definition
With insufficient damping, people in step with each other can cause resonant oscillations 

