waecE-LEARNING
Physics Paper 2, May/June. 2010  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Main
General Comments
Weakness/Remedies
Strength











Question 2

A force of 40 N is applied at the free end of a wire fixed at one end to produce an
extension of 0.24 nun. if the original length and diameter of the wire are 3 m and 2.0 nun
respectively, calculate the:
(a)       stress on the wire;
(b)       strain in the wire.

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Observation

Many candidates messed up with the calculations of the cross-sectional area of the wire as they could not convert millimeters to metres and in the poor handling of the standard form (decimals) Not much difficulty was encountered with the correct formula and computation for strain.
The expected answers are:
(a)        Stress = Force = F
                            Area    A
            
          =        40
3.14 (1.0 X 10-3)2
= 1.27 X 10-7 Nm-2
(b)       Strain = Extemion or       e
                           Length                l
= 0.24 X 10-3
3
= 8.0 X 10-5

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