Physics Mock Test 2 Practice

1. One light year is a unit of:

• A. Time
• B. Speed
• C. Distance (Correct)
• D. Energy

Explanation: One light year is the distance travelled by light in one year in vacuum ≈ 9.46 × 10¹⁵ m.

2. The derivative of sin x with respect to x is:

• A. −sin x
• B. cos x (Correct)
• C. −cos x
• D. tan x

Explanation: d(sin x)/dx = cos x . This is a fundamental derivative formula in calculus.

3. In a velocity-time graph, a straight line with positive slope represents:

• A. Uniform velocity
• B. Uniform deceleration
• C. Uniform acceleration (Correct)
• D. Non-uniform motion

Explanation: Slope of v-t graph = acceleration. A straight line with positive slope means constant positive acceleration — uniform acceleration .

4. A satellite orbits Earth at radius r with speed v. The time period T is:

• A. 2πr/v (Correct)
• B. πr/v
• C. 2πv/r
• D. πv/r

Explanation: Circumference = 2πr, Speed = v. Time = distance/speed = 2πr/v .

5. Blocks of 2 kg and 5 kg together on frictionless surface. F = 21 N on 5 kg block. Both move together. Acceleration is:

• A. 3 m/s² (Correct)
• B. 4.2 m/s²
• C. 7 m/s²
• D. 10.5 m/s²

Explanation: a = F/(m₁+m₂) = 21/7 = 3 m/s² .

6. Bullet mass doubles (same v). New KE:

• A. Same
• B. Halved
• C. Doubled (Correct)
• D. 4 times

Explanation: KE = ½mv². m→2m at same v: KE is doubled .

7. Angular momentum L = Iω. Its SI unit is:

• A. kg·m/s
• B. kg·m²/s (Correct)
• C. N·m
• D. J·s

Explanation: L = Iω. Units = kg·m² × rad/s = kg·m²/s (same as J·s).

8. Escape velocity formula:

• A. √(gR)
• B. √(2gR) (Correct)
• C. √(gR/2)
• D. 2√(gR)

Explanation: v_e = √(2GM/R) = √(2gR) .

9. Water (B = 2×10⁹ Pa) is subjected to extra pressure 2×10⁷ Pa. Fractional volume decrease:

• A. 1/100 (Correct)
• B. 1/1000
• C. 1/10
• D. 1/200

Explanation: ΔV/V = P/B = 2×10⁷/2×10⁹ = 1/100 .

10. A ship can float in sea because:

• A. It is large
• B. Its average density < seawater density (Correct)
• C. Made of steel
• D. Driven by engine

Explanation: Ship floats because its average density (including air) .

11. A spring of constant 140 N/m is compressed by 0.1 m. Energy stored is:

• A. 14 J
• B. 0.7 J (Correct)
• C. 1.4 J
• D. 0.35 J

Explanation: Spring energy = (1/2)kx^2 = 0.5 x 140 x 0.01 = 0.7 J.

12. Which of the following pairs are both base (fundamental) SI units?

• A. Ampere and Newton
• B. Kilogram and Metre (Correct)
• C. Joule and Watt
• D. Pascal and Hertz

Explanation: The 7 SI base units include kilogram (mass) and metre (length). Newton, Joule, Watt, Pascal, and Hertz are all derived units.

13. The resultant of two vectors is minimum when the angle between them is:

• A. 0°
• B. 45°
• C. 90°
• D. 180° (Correct)

Explanation: R = √(A² + B² + 2AB cosθ). When θ = 180°, cosθ = −1, R = |A − B| which is minimum.

14. Two bodies of different masses are dropped simultaneously from the same height in vacuum. They reach the ground:

• A. At different times
• B. Simultaneously (Correct)
• C. Heavier one first
• D. Lighter one first

Explanation: In vacuum, all bodies fall with the same acceleration g. They reach the ground simultaneously (Galileo's law).

15. A cricket ball is hit at 45° with velocity 20 m/s. Time of flight (g = 10 m/s²) is:

• A. √2 s
• B. 2√2 s (Correct)
• C. 4 s
• D. 2 s

Explanation: T = 2usinθ/g = 2×20×(1/√2)/10 = 40/(10√2) = 4/√2 = 2√2 s .

16. The angle of friction λ and coefficient of friction μ are related by:

• A. μ = sinλ
• B. μ = cosλ
• C. μ = tanλ (Correct)
• D. μ = cotλ

Explanation: At the angle of friction λ: tanλ = friction/normal = μ .

17. Block (4 kg) starts from rest on rough incline (h = 5 m, μ = 0.2, θ = 30°, g = 10 m/s²). Speed at bottom:

• A. 8 m/s
• B. √80 m/s
• C. 6 m/s
• D. √60 m/s (Correct)

Explanation: L = h/sin30° = 10 m. W_net = mgh − μmg cos30°·L = 200 − 40√3. v ≈ √60 m/s .

18. A skater pulls arms in. Moment of inertia decreases. Angular velocity:

• A. Decreases
• B. Increases (Correct)
• C. Stays same
• D. Becomes zero

Explanation: L = Iω = constant. If I decreases, ω increases .

19. If mass of planet doubles and radius doubles, escape velocity:

• A. Same (Correct)
• B. √2 times
• C. 2 times
• D. Half

Explanation: v_e = √(2GM/R). M→2M, R→2R: v_e = √(2G×2M/2R) = √(2GM/R) = same .

20. A rubber block (G=0.4 MPa, area=1 cm², height=1 cm) is sheared by 1 N force. Lateral displacement:

• A. 0.025 mm
• B. 0.25 mm (Correct)
• C. 2.5 mm
• D. 0.0025 mm

Explanation: τ = F/A = 1/10⁻⁴ = 10⁴ Pa. shear strain = τ/G = 10⁴/(4×10⁵) = 0.025. Δx = shear strain × h = 0.025×10⁻² m = 0.025 mm? = 0.25 mm . Let me recalc: Δx = (F/A)/G × h = (10⁴/4×10⁵)×0.01 = 0.025×0.01 = 2.5×10⁻⁴ m = 0.25 mm .

21. Buoyant force on an object depends on:

• A. Shape of object
• B. Weight of object
• C. Volume submerged and fluid density (Correct)
• D. Speed of fluid

Explanation: F_B = ρ_fluid × V_submerged × g. Depends on volume submerged and fluid density .

22. A body moves in a circle of radius 4 m with speed 4 m/s. Centripetal acceleration is:

• A. 4 m/s^2 (Correct)
• B. 6 m/s^2
• C. 2 m/s^2
• D. 16 m/s^2

Explanation: Centripetal acceleration = v^2/r = 16/4 = 4 m/s^2.

23. The dimensional formula of work is same as that of:

• A. Force
• B. Power
• C. Energy (Correct)
• D. Pressure

Explanation: Work = Force × Displacement = [MLT⁻²][L] = [ML²T⁻²]. Energy also has the same dimensions [ML²T⁻²]. Work and energy are dimensionally equivalent.

24. sin²θ + cos²θ equals:

• A. 0
• B. 2
• C. sin 2θ
• D. 1 (Correct)

Explanation: sin²θ + cos²θ = 1 is the fundamental Pythagorean trigonometric identity, valid for all values of θ.

25. A train starts from rest and accelerates uniformly at 2 m/s². The distance covered in 10 seconds is:

• A. 20 m
• B. 100 m (Correct)
• C. 200 m
• D. 40 m

Explanation: s = ut + ½at² = 0 + ½(2)(100) = 100 m .

26. A stone (radius 0.5 m, 2 rev/s) has centripetal acceleration:

• A. 8π² m/s² (Correct)
• B. 4π² m/s²
• C. 2π² m/s²
• D. π² m/s²

Explanation: ω = 2πf = 4π rad/s. a = rω² = 0.5 × 16π² = 8π² m/s² .

27. Two blocks (3 kg and 5 kg) connected by string on frictionless surface. Force 16 N pulls the 5 kg block. Tension in string is:

• A. 6 N (Correct)
• B. 10 N
• C. 16 N
• D. 4 N

Explanation: a = 16/8 = 2 m/s². T = 3×2 = 6 N .

28. Work done moving charge q through potential difference V:

• A. q/V
• B. V/q
• C. qV (Correct)
• D. q²V

Explanation: W = qV. Answer: qV .

29. Particle (m=0.5 kg) moves in circle (r=2 m) at v=4 m/s. Angular momentum:

• A. 4 kg·m²/s (Correct)
• B. 8 kg·m²/s
• C. 16 kg·m²/s
• D. 2 kg·m²/s

Explanation: L = mvr = 0.5×4×2 = 4 kg·m²/s .

30. Orbital velocity of satellite at radius r (from centre, mass M):

• A. √(GM/r) (Correct)
• B. √(2GM/r)
• C. √(GMr)
• D. GM/r

Explanation: Orbital velocity v₀ = √(GM/r) .