AH Exp – Mechanics 04 – Variation of angular acceleration with torque

Aim – To investigate the relationship between the torque applied to a turntable and the angular acceleration.

Instructions

The apparatus is set up so that when the mass is released, it falls to the ground and applies a torque to the turntable.
The turntable has a mask attached to it which has a length of 30 cm and a width if 1 cm.
This passes through a light beam after one revolution and Timer 1 measures the time for the 1 cm width to pass through the beam.
Timer 2 can be used to measure the time taken for one revolution.
A brake is applied to bring the turntable to a halt in one further revolution.

▪ Start the turntable by releasing the mass. Timer 2 is started automatically. Stop Timer 2 when the turntable has completed one revolution.
▪ Note the time on Timer 1 and Timer 2. Repeat several times and find an average value of the time for the mask to pass through the light beam and an average time for the turntable to complete one revolution.
▪ Find the angular displacement of the turntable as the mask passes through the light beam. ( Find the width of the mask as a fraction of the circumference, radius 30 cm. Multiply this fraction by the number of radians in one revolution.
▪ Find the angular velocity as the mask passes through the light beam. (angular displacement / time).
▪ Find the angular acceleration of the turntable, using the equations of motion for circular motion.
▪ Each mass is 10 g. The pulley has a radius of 5 cm. Find the torque applied to the turntable
▪ Repeat for different values of mass applying a torque.
▪ Draw a graph to show the relationship between angular acceleration and torque.

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