Free Physics of Solids MCQs with Answers

271. if both the length and radius of the rod are doubled, then modulus of elasticity will:

• A. inerease
• B. Deerease
• C. Remains the same
• D. Be doubled

Explanation: When the length ( L ) and radius ( r ) of a rod are doubled, the new length and radius are ( 2L ) and ( 2r ) respectively. The modulus of elasticity ( E ) is defined as the ratio of stress to strain, and is given by: E= Stress/StrainBy solving it, we find that modulus of elasticity become half.But it is an intrinsic property of a material, meaning it does not change with the dimensions of the material. Therefore, if both the length and radius of the rod are doubled, the modulus of elasticity will remain unchanged.

272. A force of 500 N is applied to one end of a cylindrical steel rod of diameter 50cm, the tensile stress is;

• A. 1.5 x 10^5Nm- 2
• B. 2.5 x 10^5Nm- 2
• C. 2.5 x 10^3Nm- 2
• D. 1 x 10^5Nm- 2

Explanation: We use the formula: σ= F/A Given:Force (F) = 500 NDiameter of the rod = 50 cm = 0.5 mThe cross-sectional area of a cylinder is calculated using the formula for the area of a circle ( A = πr2 ), where ( r ) is the radius of the circle.The radius is half of the diameter, so:r =0.5m/2 =0.25mNow, we can calculate the area:A = π(0.25)2 = π(0.0625 = 0.19635m² (rounded to 5 decimal places)Finally, we can calculate the tensile stress: σ = 500/0.19635 = 2546.48 Nm-2So, the tensile stress is approximately 2546.48 or 2.5×103Nm- 2.

273. Which of the following is the Young Modulus of steel?

• A. 20 x 10^9N/m2
• B. 3.9 x 10^-9N/m2
• C. 2 x 10^11N/m2
• D. 1.5 x 10^9N/m2

Explanation: The young modulus of steel is 20×1010 Pa which is 20×109N/m2.

274. A wire is stretched to four times of its length its strain is

• A. 0.5
• B. 4
• C. 3
• D. 1

Explanation: As, Strain= ΔL/Lwhere, ΔL=4L-L=3LSo, the strain is: Strain= ΔL/L =3L/L =3So, the strain is 3. This is a unitless quantity as it is a ratio of lengths.

275. If a material becomes more resistant to shear deformation, then shear modulus will

• A. increase.
• B. decrease.
• C. become zero.
• D. remain constant.

Explanation: A higher shear modulus indicates that a material is more resistant to shear deformation. Conversely, a material that is easily deformed under shear stress will have a lower shear modulus.Conclusion:Therefore, if a material becomes more resistant to shear deformation, its shear modulus will increase.

276. Which of the following is classified as a main rock?

• A. Metamorphic
• B. Sedimentary
• C. Igneous
• D. Both Options A and B are correct

Explanation: Option A; Metamorphic rocks started out as some other type of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Option B: Common sedimentary rocks include sandstone, limestone, and shale. These rocks often start as sediments carried in rivers and deposited in lakes and oceans. When buried, the sediments lose water and become cemented to form rock.Option C: Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface.

277. Ancient glass becomes milky due to

• A. Refraction
• B. Crystallization
• C. Volatilization
• D. Dispersion

Explanation: Ancient glass, an amorphous solid, undergoes alternate heating due to exposure to the sun during the day and cooling at night and is converted into partly crystalline form which results in the milky appearance. Refraction is the bending of light as it moves from a transparent substance into another. Volatilization is when a solid or liquid chemical substance is converted into vapours.

278. Which one of them is known as super cooled liquids?

• A. Glass
• B. Diamond
• C. Silica
• D. Carbon

Explanation: Amorphous solids have the tendency to flow slowly. It does not form a crystalline solid structure as particles in solids do not move but here it moves. Hence it is called a supercooled liquid.Glass is amorphous solid

279. A piece of copper is drawn into continuous wire. What behavior is the copper exhibiting?

• A. Brittle only
• B. Elastic only
• C. Plastic Only
• D. Both brittle and elastic

Explanation: For stresses beyond the elastic limit, a material exhibits plastic behaviour. This means the material deforms irreversibly and does not return to its original shape and size, even when the load is removed.

280. The force applied on unit area to produce any change in the volume or length of a body is called:

• A. Strain
• B. Stress
• C. Elasticity
• D. Equilibrium

Explanation: When the force applied produces a change in length or volume of the object then is it called stress, otherwise the term strain is used.