CAIE A-Level Physics 12.1 Kinematics of Uniform Circular Motion

Practise using radians, angular speed, period, frequency, radius and tangential speed in uniform circular motion and interpreting their relationships.

Exam points

define and use radians and angular speed for uniform circular motion
calculate angular speed, period, frequency, radius or linear speed using ω = 2π/T and v = rω
interpret the relationship between angular and tangential quantities

Covered syllabus points

12.1.1—The radian and express angular displacement in radians 12.1.2—The concept of angular speed 12.1.3—Ω = 2π / T and v = rω

[Maximum number: 3]

(a)

Define the radian.

[ 1 ]

(b)

The metal disc in Fig. 1.1 has a radius of 9.3 cm .

The centre of gravity of the modelling clay is 1.2 cm from the rim of the disc and moves with a speed of $0.68 \mathrm{~ms}^{-1}$ .

[ 2 ]

(i)

Calculate the angular speed $\omega$ of the disc.
$\omega=$ $\mathrm{rad\,s^{-1}}$

[ 2 ]

$v=r \omega$

C1

$\begin{aligned} \omega =0.68 /(0.093-0.012) =8.4 \mathrm{rad} \mathrm{~s}^{-1} \end{aligned}$

A1

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Covered syllabus points

12.1 Kinematics of uniform circular motion question 1

Question (a)

Question (b)

Question (i)