GCSE Engineering, Testing and drawing. Usually met in years 9 to 11.
Calculate pressure, stress, strain, Young’s modulus and factor of safety, the equations named in the AQA specification.
What you practise
Pressure and stress = force ÷ area
Strain and Young’s modulus
Factor of safety and round bars
Starts with pressure on a flat area and builds to the stress in a round bar. Practice moves up a level when a round goes well and down when it does not.
Sample questions
Each sample comes with the method and the reason every wrong option is wrong. Real practice rounds are ten questions at your level.
Sample question, level 2 of 5
A bar 8 mm wide and 10 mm thick carries a pulling force of 7,600 N. What is the stress in the bar?
95 N/mm²
422.222 N/mm²
0.011 N/mm²
211.111 N/mm²
950 N/mm²
Show the answer and method
Answer: A, 95 N/mm²
The method: Area = 8 × 10 = 80 mm². Stress = force ÷ area = 7,600 ÷ 80 = 95 N/mm².
Why the other options are wrong:
B, 422.222 N/mm²: The width and thickness were added. The cross-sectional area is width × thickness.
C, 0.011 N/mm²: The division is upside down. Stress = force ÷ area.
D, 211.111 N/mm²: That uses the perimeter. Use the cross-sectional area.
E, 950 N/mm²: Only the width was used. Divide by the whole cross-sectional area.
Sample question, level 4 of 5
A test piece is under a stress of 60 N/mm² and a strain of 0.001. What is its Young’s modulus?
