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Mechanical Properties of Solids appeared 21 times across 3 years — 2.4% of Physics. This question is from Elasticity and Hooke's Law.

Year 2026 2025 2024 Total
Questions 4 9 8 21

Two metallic wires P and Q have same volume and are made up of same material. If their area of cross sections are in the ratio 4:1 and force F₁ is applied to P, an extension of Δ l is produced. The force which is required to produce same extension in Q is F₂. The value of (F₁)/(F₂) is:

Numerical Answer Type:
Enter a numerical value Answer: 16 to 16 +4 marks

Solution & Explanation

Related Formula

The Young's modulus Y is:

Y = StressStrain = (F / A)/(Δ l / l) = (F l)/(A Δ l)

Solving for extension Δ l:

Δ l = (F l)/(A Y)

Since volume V = A l, we substitute l = (V)/(A):

Δ l = (F V)/(A² Y)
Core Logic

We are given that the wires are made of the same material (Y is constant) and have the same volume (V is constant). Also, we want to achieve the same extension (Δ l is constant).

Thus, from the formula:

Δ l ∝ (F)/(A²) F ∝ A²
Step 1: Calculate the Force Ratio

Using the proportionality for both wires:

(F₁)/(F₂) = ( (A₁)/(A₂) )²

Given the cross-sectional area ratio is 4:1:

(A₁)/(A₂) = (4)/(1)

Substitute this into the ratio equation:

(F₁)/(F₂) = ( (4)/(1) )² = 16
Pattern Recognition

For a constant volume and material, extension Δ l ∝ (F)/(A²). Since area ratio is 4, the required force ratio is 4² = 16.

Chapter Mix

Class 11 Physics: Mechanical Properties of Solids

Reference Study Guides

More Mechanical Properties of Solids Previous-Year Questions — Page 5

Q58 jee_main_2024_31_jan_morning Bulk Modulus
The depth below the surface of sea to which a rubber ball be taken so as to decrease its volume by 0.02% is ________ m. (Take density of sea water = 10³ kgm⁻³, Bulk modulus of rubber = 9 × 10⁸ Nm⁻², and g = 10 ms⁻²)
Numerical Answer. Answer: 18 to 18

Solution

Related Formula
β = (-Δ P)/((Δ V)/(V)) Δ P = ρ g h
Core Logic

The change in pressure Δ P is the hydrostatic pressure at depth h.

Δ P = -β (Δ V)/(V) ρ g h = -β (Δ V)/(V)
Step 2: Calculation

Given values: ρ = 10³ kg/m³ g = 10 m/s² β = 9 × 10⁸ N/m² (Δ V)/(V) = -0.02% = -(0.02)/(100)

Substitute into the equation:

10³ × 10 × h = - (9 × 10⁸) × (-(0.02)/(100)) 10⁴ × h = 9 × 10⁸ × 2 × 10⁻⁴ 10⁴ h = 18 × 10⁴ h = 18 m
Chapter Mix

Class 11 Physics: Mechanical Properties Of Solids Class 11 Physics: Mechanical Properties Of Fluids

More Mechanical Properties of Solids Questions — jee_main_2024_29_january_evening

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