CP5 Determine the Young's Modulus of a Material

Question 1

How?

Answer 1

Clamp the wire to a fixed point and have the wire attached to a pulley making sure the system is taut.

Have paper strips on the wire with a ruler to find the original length

Find the cross-sectional area by measuring the diameter with a micrometre

Add 100g masses measuring the extension and force (mg)

Repeat until the wire snaps

Calc stress = f/a and strain = x/L

graph of stress against strain with gradient being young modulus

Question 2

Reduce uncertainty?

Answer 2

Use a large distance between the pieces of tape
Use a thick wire for a large range of values
Take multiple measurements of the diameter of the wire
Make sure there a larger extensions as they are easier to measure
Make sure the stretching (necking) is finished.

Question 3

Why should the temperature be kept constant?

Answer 3

As metals undergo thermal expansion when heated

Question 4

Why is the thickness of the wire important?

Answer 4

Too thick and the values of extension would be small and too thin and it will break/ plastically deform very early

Question 5

Why is the length important?

Answer 5

As if the length determines how much the wire will extend

Question 6

Safety hazards

Answer 6

Snapping wire and falling mass
So
Wear goggles and have a sand tray below mass

Question 7

Why is a long wire better?

Answer 7

More extension, so easier to read

Question 8

What is a good way to measure the diameter of the wire?

Answer 8

Measure 2 times perpendicular to each other to ensure it’s circular