Periodic motion definitions

Question 1

Amplitude

Answer 1

the maximum displacement of an oscillating object from its equilibrium position.

Question 2

Angular displacement

Answer 2

the angle an object in circular motion turns through. If its time period is T and its frequency is f, its angular displacement in time t, in radians = 2πft = 2πt/T.

Question 3

Angular speed ω

Answer 3

the rate of change of angular displacement of an object in circular (or orbital or spinning) motion.

Question 4

Angular frequency ω

Answer 4

essentially the same as angular speed, for an object oscillating at frequency f in simple harmonic motion, its angular frequency = 2πf.

Question 5

Centripetal acceleration

Answer 5

acceleration directed towards the centre of circular motion

Question 6

Centripetal force

Answer 6

the resultant force on an object that moves along a circular path, directed towards the centre of the circle

Question 7

Damped oscillations

Answer 7

oscillations that reduce in amplitude due to the presence of resistive force such as friction or drag.

Question 8

Light damping

Answer 8

Damping which causes the amplitude of the oscillations to gradually decraese

Question 9

Heavy damping

Answer 9

damping that results in the system slowly returing to equilibrium without oscillating.

Question 10

Critical damping

Answer 10

Damping that results in the system returning to the equilibrium position in the least possible time without oscillating.

Question 11

Dissipative forces

Answer 11

forces that transfer energy that is wasted.

Question 12

Equilibrium

Answer 12

state of an object when at rest or in uniform motion.

Question 13

Forced vibrations

Answer 13

vibrations (oscillations) of a system subjected to an external periodic force.

Question 14

Free vibrations

Answer 14

vibrations (oscillations) where there is no damping and no periodic force acting on the system, so the amplitude of the oscillations is constant.

Question 15

Frequency

Answer 15

of an oscillating object is the number of cycles of oscillation per second.

Question 16

Natural frequency

Answer 16

the frequency of free oscillations of an oscillating system (no damping and no periodic force acting on the system)

Question 17

Periodic force

Answer 17

a force that varies regularly in magnitude with a definite time period.

Question 18

Resonance

Answer 18

the amplitude of vibration of an oscillating system subjected to a periodic force is largest when the periodic force has the same frequency as the resonant frequency of the system.

Question 19

Resonant frequency

Answer 19

the frequency of an oscillating system in resonance (when the amplitude of oscillation is largest).

Question 20

Simple harmonic motion

Answer 20

motion of an object if its acceleration is proportional to the displacement of the object from equilibrium and is always directed in the opposite direction to the displacement (towards the equilibrium position).

Question 21

Time period

Answer 21

time taken for one complete oscillation

Question 22

Uniform circular motion

Answer 22

motion of an object moving at constant speed along a circular path.