Determining the Young's Modulus of a material (3.4)

Question 1

What equipment do you need to determine the Young’s modulus of a material?

Answer 1

G-clamp, test wire, tape marker, ruler with mm markings, pulley, weights, micrometer

Question 2

Why should the test wire when determining Young’s Modulus be as long and thin as possible?

Answer 2

The longer and thinner the wire, the more it extends under the same force, reducing the uncertainty in measurements

Question 3

How do you set up the experiment to find the Young’s Modulus of a wire?

Answer 3

1) Clamp one end of the wire with a G-clamp to the bench. 2) Make sure there is at least 2 metres of wire over the bench before it reaches the pulley
3) Hang the smallest weight necessary to straighten the wire on the end.
4) Attach a marker about 3/4 of the way down the wire

Question 4

How do you find the Young’s Modulus of a wire (assuming equipment has been set up)?

Answer 4

1) First, take diameter readings at five points along the wire using a micrometer. Average these to get a reading for diameter, and calculate the cross sectional area using _
2) Measure the distance between the clamped end of the wire and the marker, record as original length L
3) Place 0mm of ruler at the marker
4) Add weights to the end of the wire in 1N intervals, recording the extension in mm from the ruler
5) Use the results to calculate stress and strain at each interval
6) Plot a scatter graph of stress against strain
7) The gradient of the line of best fit is the Young’s Modulus