A work of 2 x 10^-2 J is done on a wire of length 50 cm and area of cross-section 0.5 mm². If the Young's modulus of the matenal of the wire is 2 × 10¹⁰ Nm^-2, then the wire must be

• elongated to 50.1414 cm

• contracted by 2.0 mm

• stretched by 0.707 mm

• of length changed to 49.293 cm

32.

In a cubic unit cell of bcc structure, the lattic points (i.e., number of atoms) are

• 2

• 6

• 8

• 12

The modulus of elasticity is dimensionally equivalent to

• strain

• force

• stress

• coefficient of viscosity

A wire of length L and area of cross-section A is stretched through a distance x metre by applying a force F along length, then the work done in this process is : (Y is Young's modulus of the material)

• $\frac{1}{2} \left(\mathrm{A} . \mathrm{L}\right) \left(\frac{\mathrm{Yx}}{\mathrm{L}}\right) \left(\frac{\mathrm{x}}{\mathrm{L}}\right)$

• $\left(\mathrm{A} . \mathrm{L}\right) \left(\mathrm{YL}\right) \left(\frac{\mathrm{x}}{\mathrm{L}}\right)$

• $2 \left(\mathrm{A} . \mathrm{L}\right) \left(\mathrm{YL}\right) \left(\frac{\mathrm{x}}{\mathrm{L}}\right)$

• $3 \left(\mathrm{A} . \mathrm{L}\right) \left(\mathrm{YL}\right) \left(\frac{\mathrm{x}}{\mathrm{L}}\right)$

A uniform plank of Young's modulus Y is moved over a smooth horizontal surface by a constant horizontal force F. The area of cross-section of the plank is A. The compressive strain on the plank in the direction of the force is

• $\frac{\mathrm{F}}{\mathrm{AY}}$

• $\frac{2\mathrm{F}}{\mathrm{AY}}$

• $\frac{1}{2}\frac{\mathrm{F}}{\mathrm{AY}}$

• $\frac{3\mathrm{F}}{\mathrm{AY}}$

Young's modulus of perfectly rigid body material is

• infinite

• zero

• 10 × 10¹⁰ / m²

• 1 × 10¹⁰ N/m²

Which one of the following is not a unit of Young's modulus?

• Nm^-1

• Nm^-2

• dyne cm^-2

• Mega pascal

Which of the following substances has the highest elasticity ?

• Sponge

• Steel

• Rubber

• Copper

The following four wires of length L and radius r are made of the same material. Which of these will have the largest extension,when the same tension is applied ?

• L = 1000 cm, r = 0.2 mm

• L = 2000 cm, r = 0.4 mm

• L = 3000 cm, r = 0.6 mm

• L = 4000 cm, r = 0.8 mm

The ratio of hydraulic stress to the corresponding strain is known as

• Young's modulus

• compressibility

• Rigidity modulus

• Bulk's modulus