The Young modulus for the wire’s material can be measured with the apparatus shown in Fig. 3.1. One end of the wire is held at C, and a marker is fixed to the wire above scale S. Masses are added to the other end to apply a stretching force. The reading X from the marker on scale S is measured for a range of forces F acting at the wire’s end. Fig. 3.2 shows the relationship between X and F.
(a)[3]
When $F = 0$, the distance from C to the marker is $3.50\,\text{m}$. The wire’s diameter is $0.38\,\text{mm}$. Use the gradient of the line in Fig. 3.2 to calculate the Young modulus $E$ of the wire material in TPa.
(b)[1]
The test is carried out again with a thicker wire of the same material and length. State how the range of the force $F$ should be altered so that the scale readings cover the same range as in Fig. 3.2.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applies $E = \text{stress}/\text{strain} = (F/A)/(e/l)$” …