HSSC-II (12th Class) Physics Unit-17: Physics of Solids : Numerical Problems List (Punjab Curriculum and Text Board, Lahore) With Verified Answers

17.1 A 1.25 cm diameter cylinder is subjected to a load of 2500 kg. Calculate the stress on the bar in mega Pascal. (Ans: 200 MPa)

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17.2 A 1.0 m long copper wire is subjected to stretching force and its length increases by 20 cm. Calculate the tensile strain and the percent elongation which the wire undergoes. (Ans :0 .2 0 .2 0 % )

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17.3 A wire 2.5 m long and cross-section area 10⁻⁵ m² is stretched 1.5 mm by a force of 100 N in the elastic region. Calculate (i) the strain (ii) Young's modulus (iii) the energy stored in the wire. (Ans : 6.02 x 10⁻⁴, 66 x 10¹⁰  Pa, 7.5 x 10⁻² J)

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17.4 What stress would cause a wire to increase in length by 0.01% if the Young's modulus of the wire is 12 x 10¹⁰ Pa. What force would produce this stress if the diameter of the wire is 0.56 mm? (A n s: 1.2 x 10⁷ Pa, 2.96 N)

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17.5 The length of a steel wire is 1.0 m and its cross-sectional area is 0.03 x 10⁻⁴ m². Calculate the work done in stretching the wire when a force of 100 N is applied within the elastic region. Young's modulus of steel is 3.0 x 10¹¹ N m⁻². (Ans : 5.6 x 10⁻³ J )

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17.6 A cylindrical copper wire and a cylindrical steel wire each of length 1.5 m and diameter 2.0 mm are joined at one end to form a composite wire 3.0 m long. The wire is loaded until its length becomes 3.003 m. Calculate the strain in copper and steel wires and the force applied to the wire. (Young's modulus of copper is 1.2 ｘ 10¹¹ Pa and for steel is 2.0 ｘ 10¹¹ Pa). (Ans : 1.25 ｘ10⁻³, 7.5 ｘ  10⁻⁴,  471  N )

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