Physics 9702 · AS & A Level · Centripetal acceleration

Centripetal acceleration — practice question

(a)[1]

Define the radian in terms of angle measurement.

(b)[2]

The minute hand of a clock turns at a steady angular speed about the clock face, making one complete turn each hour. A small piece of modelling clay is attached to the hand, with its centre of gravity at a distance $L$ from the fixed end of the hand, as shown in Fig. 1.1. Calculate the angular speed $\omega$ of the minute hand.

(c(i))[1]

In a time interval of $1400\,\text{s}$, the centre of gravity of the piece of modelling clay in Fig. 1.1 travels a total distance of $0.44\,\text{m}$. Calculate the angle through which the minute hand moves during this interval.

(c(ii))[2]

Determine the value of $L$.

(c(iii))[2]

Calculate the size of the centripetal acceleration of the piece of modelling clay.

(d)[2]

Use your answer in (c)(iii) to explain why the change with time in the magnitude of the force exerted by the minute hand on the piece of modelling clay is negligible while the minute hand completes one full revolution.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: The angle is subtended at the centre of a circle when the arc length is equal to the radius.

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