Learner Resource 1 – Teacher instructions
Definitions of terms used in circular motion
It is suggested that learners are provided with this sheet. Teachers could choose to present it as a
matching exercise, with each statement on a separate piece of paper.
Term
Definition
Unit
Angular velocity, ω
Rate of change of angular
displacement
radians per second, rad s-1
Angle
Angle at centre of circle
subtended by an arc equal
to the radius
radian, rad
Period, T
Time taken for one
complete cycle
second, s
Frequency, f
Number of complete cycles
per second
Hertz, Hz
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Circular and Simple Harmonic Motion
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Equations
Term
Definition
Unit
Angular velocity, ω
ω = 2π / T, or ω = 2πf
rad s-1
Constant speed in a circle,
v
v=ωr
ms-1
Centripetal force, F
Centripetal acceleration, a
𝐹=
𝑎=
𝑚𝑣 2
𝑟
Newtons
𝑣2
𝑟
m s-2
Centripetal force, F
𝐹 = 𝑚𝜔2 𝑟
Newtons
Centripetal acceleration, a
𝑎 = 𝜔2 𝑟
m s-2
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Circular and Simple Harmonic Motion
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Definitions of terms used in oscillations
Term
Definition
Unit
Displacement, x
Overall change in position
from equilibrium point
metres, m
Amplitude, A
Period, T
Frequency, f
Angular frequency, ω
Phase difference
maximum magnitude of
displacement from
equilibrium point
the time taken for one
complete cycle
the number of complete
cycles in one second
angular displacement in unit
time
part of a cycle by which two
oscillations of the same
frequency are out of step
metres, m
seconds, s
Hertz, Hz
rad s-1
Radians
Acceleration in SHM, a
a = -ω2x (definition of SHM)
ms-2
Velocity, v
𝑣 = ±𝜔 √𝐴2 − 𝑥 2
ms-1
Maximum velocity, vmax
vmax = ωA
ms-1
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