This diagram shows a turntable with a rod attached to it a distance 15 cm from the centre. The turntable is illuminated from the side so that a shadow is cast on a screen.

A simple pendulum is placed behind the turntable and is set oscillating so that it has an amplitude equal to the distance of the rod from the centre of the turntable.
The speed of rotation of the turntable is adjusted. When it is rotating at 1.5 revolutions per second the shadow of the pendulum and the rod are found to move back and forth across the screen exactly in phase.
a. Explain what is meant by the term in phase.
b. Write down an equation to describe the displacement x of the pendulum from its equilibrium position and the angular frequency of the oscillation of the pendulum.
c. The turntable rotates through 60° from the position of maximum displacement shown in the diagram.
i. Calculate the displacement (from its equilibrium position) of the pendulum at this point.
ii. Calculate its speed at this point.
iii. Through what further angle must the turntable rotate before it has this speed again?

Transcribed Image Text:

View from front View from above screen screen -pendulum -pendulum rod rod -turntable -turntable lamp to illuminate the setup 15 cm Figure 18.42