This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “Stress and Strain”.
1. If the stress is S and the Young’s modulus is Y of material of a wire, the energy stored in the wire per unit volume is?
a) 2Y/S
b) S/2Y
c) 2S2 Y
d) S2/ 2Y
View Answer
Explanation: Elastic potential energy stored per unit volume,
u=1/2×Stress×Strain=1/2×Stress×Stress/Y=S2/2Y.
2. Two wires have the same material and have the same volume. However wire 1 had cross sectional area A and wire 2 has cross sectional area 3A. If the length of wire 1 increases by ∆x on applying force F, how much force is needed to stretch wire 2 by the same amount?
a) F
b) 4F
c) 6F
d) 9F
View Answer
Explanation: Y=F/A l/∆l=F/A2 Al/∆x=FV/(A2 ∆x)
F=Y∆x/V A2
FαA2
F‘=(3A)2
F‘/F=9
F‘=9F.
3. Amorphous solids are true solids.
a) True
b) False
View Answer
Explanation: Amorphous solids have disordered arrangement of atoms or molecules. The molecules of the liquid are free to move but the molecules of an amorphous solid are almost fixed at their positions. That is why we say amorphous solids are super-cooled liquids of high velocity.
4. An example of a perfectly plastic body is ___________
a) Quartz
b) Crystal
c) Putty
d) Rubber
View Answer
Explanation: If on the removal of deforming force, a body does not regain its original configuration even a little, then it is said to be a perfectly plastic body. This putty is a perfectly plastic body.
5. No material is perfectly elastic.
a) True
b) False
View Answer
Explanation: All materials undergo a change in their original state, howsoever small it may be, after the removal of deforming force. Hence, there is no such material that is perfectly elastic.
6. A given quantity if an ideal gas is at pressure P and absolute temperature T. What is the isothermal bulk modulus of the gas?
a) 2P/3
b) P
c) 3P/2
d) 2P
View Answer
Explanation: Isothermal bulk modulus of a gas = Pressure of the gas = P.
7. A wire fixed at the upper end stretches by length l by applying a force F. What is the work done in stretching?
a) F/2l
b) Fl
c) 2Fl
d) Fl/2
View Answer
Explanation: W = 1/2 Stretching force×increase in length
W = 1/2 Fl.
8. The term liquid crystal refers to a state that is intermediate between ___________
a) Crystalline solid and amorphous liquid
b) Crystalline solid and vapour
c) Amorphous liquid and its vapour
d) A crystal immersed in a liquid
View Answer
Explanation: Liquid crystal is a state intermediate between crystalline solid and amorphous liquid.
9. Which of the following have well defined geometrical external shapes?
a) Amorphous solids
b) Liquids
c) Gases
d) Crystalline solids
View Answer
Explanation: Crystalline solids have well defined geometrical external shapes because the atoms and molecules are arranged in a definite geometrical repeating manner throughout the body of the crystal.
10. A body of weight mg is hanging on a string that extends in length by l. The work done in extending the string is ___________
a) mgl
b) mgl/2
c) 2mgl
d) 0
View Answer
Explanation: W=Average force × extension
W=1/2 F×l=1/2 mg×l=mgl/2.
Sanfoundry Global Education & Learning Series – Engineering Physics.
To practice all areas of Engineering Physics, here is complete set of 1000+ Multiple Choice Questions and Answers.
