Define the radian.
A horizontal circular metal disc rotates about a vertical axis, as shown in Fig. 1.1. A piece of modelling clay is fixed to the disc. At the instant when the modelling clay is in the position shown, draw on Fig. 1.1: (i) an arrow, labelled V, to show the direction of the velocity of the modelling clay; (ii) an arrow, labelled A, to show the direction of the acceleration of the modelling clay.
The metal disc in Fig. 1.1 has radius $9.3\,\text{cm}$. The centre of gravity of the modelling clay is $1.2\,\text{cm}$ from the edge of the disc and has a speed of $0.68\,\text{m s}^{-1}$. Calculate the angular speed $\omega$ of the disc.
At the instant when the modelling clay is in the position shown, draw on Fig. 1.1 an arrow, labelled $V$, to indicate the direction of the velocity of the modelling clay.
At the instant when the modelling clay is in the position shown, draw on Fig. 1.1 an arrow, labelled $A$, to show the direction of the acceleration of the modelling clay.
Calculate the acceleration $a$ of the centre of gravity of the modelling clay.
Complete Table 1.1 by placing one tick ($\checkmark$) in each row to show how the listed quantities compare for the two pieces of modelling clay.