Stress, strain and the Young modulusEdexcel A-Level Physics: Flashcards
What these 12 flashcards ask
- Define stress and give its unit.
- Define strain.
- Define the Young modulus.
- What is the gradient of a stress–strain graph?
- What is breaking stress?
- How do you find the breaking force from the breaking stress?
- How do you convert mm² to m²?
- What is the formula for the area of a wire from its diameter?
- In the Young modulus practical, why is a long, thin wire used?
- In the practical, which graph gradient gives E?
- Why is the diameter of the wire measured at several places?
- Why does the diameter give the largest percentage uncertainty in E?
Exam questions on Stress, strain and the Young modulus
- A steel wire of length 2.50 m and cross-sectional area 0.50 mm² supports a load of 80 N. The Young modulus of steel is 2.0 × 10¹¹ Pa, and the wire obeys Hooke's law.Calculate the extension of the wire.2 marks
- A student stretches a copper wire of diameter 0.60 mm and original length 1.80 m. A load of 50 N produces an extension of 1.4 mm.Explain why a long, thin wire is used in an experiment to measure the Young modulus of a metal.2 marks
- A metal rod of original length 0.400 m and cross-sectional area 1.0 × 10⁻⁴ m² is tested in tension until it breaks. The stress–strain graph is a straight line through the origin up to a stress of 2.8 × 10⁸ Pa, where the strain is 1.4 × 10⁻³. The breaking stress of the rod is 4.5 × 10⁸ Pa.Calculate the Young modulus of the metal.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).