Exam-style Questions: Deformation of Solids
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The images A and B show two different kinds of fracture.
State the two kinds of fracture, for each suggesting a material that fractures in this way.
A shows .....................................fracture,
a possible materials is ................................ .
B shows .................................... fracture,
a possible material is .................................. .
(4 Marks)
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A metal wire is suspended from a fixed point. Increasing weights are added to the lower end of wire. The stress and strain in the wire are as follows.
a) On the axis below, plot the points and draw the graph of stress against strain.
(2 Marks)
b) Use the graph (i) to calculate the Young modulus of the maetrial of the wire.
Young modulus = .......................... Pa
(3 Marks)
(Marks available: 5)
Answer outline and marking scheme for question:
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A: ductile / plastic fracture AW
e.g. metals / copper / plastics / pvc (all correct)
B: brittle / clean fracture AWv
e.g. glass / cermaic / named alloy / (cast) iron (all correct)
(4 Marks)
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a) All points plotted correctly;
Correct graph shown: straight section through origin and curve.
(2 Marks)
b) Use of point on straight line / gradient of straight line used;
Correct data from graph;
Young modulus between 1.2 x 1011 Pa and 1.3 x 1011 Pa
(3 Marks)
(Marks available: 5)