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Results: Measurement of Young's modulus
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A set of results for the steel strip are given below.

load, m (kg)
deflection, δ (10-3 m)
0 0
0.05 3
0.10 6.5
0.15
9
0.20 13
0.25
16

A graph of these results gives:

Graph of deflection vs load

The gradient of this graph is

Equation

In addition

width of strip (w) = 0.01 m
thickness of strip (h) = 0.001 m
length of strip (L) = 0.15 m

So, using equation (2)

Equation

From equation (1) with P = mg, a graph of δ against m will have a gradient

Equation

and hence

Equation

So the steel from which the strip is made has a Young's modulus of 210 GPa (close to the figure given in the properties table).

Repeating the experiment for the aluminium and polycarbonate strips gives Young's moduli of 70 GPa and 5.5 GPa respectively. These results will be used later in the TLP.

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