1R20.15 • Tensile and Compressive Stress: Young’s Modulus

Photo Shows the Demonstration Used by the University of Texas at Austin.

Instructions and Notes:

• A solid steel wire is wrapped around a rotating axle that has a mirror attached to it.
• A laser beam shines into the mirror and is reflected back towards a reference point.
• At the bottom of the wire is a 1 kg hanger to which additional kilogram masses can be added. Two 2kg masses are available for this.
• Adding weight to the bottom of the hanger stretches the wire, causing the angle of reflection to change. TO AVOID BREAKING THE WIRE, DO NOT EXCEED 5KG
• Take note of the degree measurements after each weight is added to the hanger.
• As you remove the masses, students can observe where the reflected beam returns to.
• Note: Have this demo face a wall such that the red light can be seen.

Last updated on April 4, 2023