7.1 Define the following terms: 7.1.1 Stress: Stress is the internal resistance of a body to an external force or load - NSC Mechanical Technology Welding and Metalwork - Question 7 - 2021 - Paper 1

Hooke's law articulates that the deformation of a material is directly proportional to the applied load, as long as that load does not exceed the material's elastic limit. This relationship is commonly expressed in the equation:

$ext{Stress} = E imes ext{Strain}$

where E is the modulus of elasticity of the material.

To construct the space diagram:

1. Start by plotting points A, B, C, and D according to the measurements given in the problem statement.
2. From point D, draw a vertical line to represent the 200 N force acting downward.
3. Draw the lengths of member AD at the angle of 60° and member CD at the angle of 30°, ensuring accurate angular representation.
4. Label each member clearly and indicate all forces acting on the structure.

To build the vector diagram:

1. Begin at point D and draw the reaction forces based on the dimensions specified.
2. From point D, construct the vector for the 200 N force downward.
3. Using the scale, represent each force as a line: 200 N, 150 N, and 50 N, accordingly.
4. Ensure to preserve the angle between the members and accurately represent the overall force system.

Using the vector diagram:

1. For member AD: The calculated force is between 172 N to 176 N, indicating it is a structural member supporting tension.
2. For member BD: The force measured is 100 N to 104 N, showing it also operates in tension.
3. For member CD: The force in this member is between 87 N to 91 N suggesting it functions as a tie member.