## Aerospace Materials Questions and Answers Part-1

1. The property of being liquefied due to heat is known as ______
a) stress
b) contraction
c) normalizing
d) fusibility

Explanation: The property of being liquefied due to heat is known as fusibility. Contraction is the reduction in length of material and stress is the load on the material.

2. Hardness is inversely proportional to strength.
a) True
b) False

Explanation: Hardness is directly proportional to strength. As the hardness of a material increases, it’s strength increases. Hardness is the tendency of a material to resist penetration. Strength of a material is its capacity to withstand a load.

3. Which of the following property of a material is preferred in the construction of an aircraft?
a) Ductility
b) Elasticity
c) Hardness
d) High density

Explanation: Ductility, elasticity and hardness are all preferred in the construction of an aircraft. High density is not preferred. Instead, low density is preferred.

4.What is the temperature at which steel fuses?
a) 1100°F
b) 200K
c) 2500°F
d) 3500°F

Explanation: Steel fuses at around 2500°F. Aluminium alloys fuse at around 1100°F. Fusibility is the liquefaction of a material due to heat.

5. Why do metals contract and expand?
a) Due to cooling and heating
b) Due to displacement
c) Due to repairs
d) Due to false recognition

Explanation: The cooling and heating of metals causes contraction and expansion respectively. That is the reason why railway tracks expand in summer.

6. A material elongated to 35m due to certain conditions. If it’s initial length is 7m, what is the strain of the material?
a) 21m
b) 5m
c) 7m
d) 35m

Explanation: Strain = $$\frac{Change \,in \,length}{Original \,length} = \frac{35}{7}$$ = 5m.

7. The tendency of a material to fracture without changing it’s shape is known as ______
a) brittleness
b) hardness
c) elasticity
d) carburizing

Explanation: The tendency of a material to fracture without changing it’s shape is known as brittleness. Hardness of a material is its tendency to resist penetration. Elasticity of a material is the property of the material to return to its original shape once the force causing the distortion of shape is removed.

8. Steel is one of the few materials that has a definite yield point.
a) True
b) False

Explanation: The yield point is a point after which there is an increase in deformation without a load increase. Steel is one the few materials that has a definite yield point.

9. If a material is loaded beyond its elastic limit _________
a) it returns back to it’s original shape
b) it acquires softness
c) it is permanently distorted
d) it turns to liquid