Fig 12 shows a metal bar that is being subjected to a turning force. One end of the bar is held firmly in a fixed clamp while a force is applied to the othe...
Question 1 Report
Fig 12 shows a metal bar that is being subjected to a turning force. One end of the bar is held firmly in a fixed clamp while a force is applied to the other end, causing the bar to twist along its length.
(a) Name the type of force being applied to the bar shown in Fig 12 that causes it to twist. [1]
(b) State the type of force that acts on a vertical column when a heavy roof pushes down on it. [1]
(c) Name the type of force produced when a material is stretched by being pulled apart from both ends. [1]
Answer Details
(a) The type of force causing the bar to twist is torsion. [1]
Torsion is a twisting force that occurs when one end of a member is rotated relative to the other end about its longitudinal axis. In the diagram, one end is held fixed by the clamp while a turning force (torque) is applied to the free end, causing the bar to twist along its length. Torsion creates shear stress within the material, with the maximum stress occurring at the outer surface of the bar.
(b) The force acting on a vertical column when a heavy roof pushes down on it is compression. [1]
Compression is a pushing/squeezing force that tends to shorten a member. The weight of the roof acts downward through the column, compressing it along its length. If the compressive force exceeds the column's capacity, it may crush (for short columns) or buckle (for slender columns).
(c) The force produced when a material is stretched by being pulled apart from both ends is tension. [1]
Tension is a pulling force that tends to elongate a material. The molecular bonds within the material resist being pulled apart. If the tensile force exceeds the material's ultimate tensile strength, it will fracture at its weakest cross-section.
Download The App On Google Playstore
Everything you need to excel in your exams
