University:
Cypress College
Course:
PHYS 201 C | College Physics I
Academic year:

2021
Views:

5

Pages:

22
Author:

NikkiP24

Chapter 6: Mechanical Properties of Solids EXERCISES [PAGE 112] Exercises | Q 1. (1) | Page 112 Choose the correct answer. Change in dimensions is known as 1. deformation 2. formation 3. contraction 4. strain SOLUTION Change in dimensions is known as deformation. Exercises | Q 1. (II) | Page 112 Choose the correct answer. The point on the stress-strain curve at which strain begins to increase even without Increase in stress is called 1. elastic point 2. yield point 3. breaking point 4. neck point SOLUTION The point on the stress-strain curve at which strain begins to increase even without increase in stress is called yield point. Exercises | Q 1. (iii) | Page 112 Choose the correct answer. Strain energy of a stretched wire is 18 x 103 J and strain energy per unit volume of the same wire and same cross-section is 6x103 J/m². Its volume will be 1. 3cm³ 2. 3 m³ 3. 6 m² 4.6 cm³ SOLUTION Strain energy of a stretched wire is 18 x 10-3 J and strain energy per unit volume of the same wire and same cross-section is 6x10 J/m³. Its volume will be 3 m³ Exercises | Q 1. (iv) | Page 112 Choose the correct answer. is the property of a material which enables it to resist plastic deformation. 2 1. elasticity 2. plasticity 3. hardness 4. ductility SOLUTION Hardness is the property of a material that enables it to resist plastic deformation. Exercises | Q 1. (v) | Page 112 Choose the correct answer. The ability of a material to resist fracturing when force is applied to it, is called, 1. toughness 2. hardness 3. elasticity 4. plasticity SOLUTION The ability of a material to resist fracturing when force is applied to it, is called toughness. Exercises | Q 2. (0) | Page 112 Answer in one sentence. Define elasticity. SOLUTION If a body regains its original shape and size after removal of the deforming force. It is called an elastic body and the property is called elasticity. Exercises | Q 2. (II) | Page 112 Answer in one sentence. What do you mean by deformation? SOLUTION The change in shape, size, or both of a body due to an external force is called deformation. Exercises | Q 2. (iii) | Page 112 Answer in one sentence. State the SI unit and dimensions of stress. SOLUTION 1. Sl unit: N m² or pascal (Pa) 2. Dimensions: [L-MT-2] 3 Exercises | Q 2. (iv) | Page 112 Answer in one sentence. Define strain. SOLUTION The strain is defined as the ratio of change in dimensions of the body to its original dimensions. change in dimensions Strain- original dimensions Exercises | Q 2. (v) | Page 112 Answer in one sentence. What is Young's modulus of a rigid body? SOLUTION Young's modulus is the modulus of elasticity related to change in length of an object like a metal wire, rod, beam, etc., due to the applied deforming force. Exercises | Q 2. (vi) | Page 112 Answer in one sentence. Why bridges are unsafe after very long use? SOLUTION A bridge during its use undergoes recurring stress depending upon the movement of vehicles on it. When bridge is used for long time, it loses its elastic strength and ultimately may collapse. Hence, the bridges are declared unsafe after long use. Exercises | Q 2. (vii) | Page 112 Answer in one sentence. How should be a force applied on a body to produce shearing stress? SOLUTION A tangential force which is parallel to the top and the bottom surface of the body should be applied to produce shearing stress. Exercises Q 2. (viii) | Page 112 Answer in one sentence. State the condition under which Hooke's law holds good.