A body of mass m is attached to a spring with constant k = 100 N/m. When extended by 0.2 m and released, the maximum acceleration is 50 m/s². The mass is:

The correct answer is A: 0.4 kg. Max acceleration occurs at maximum extension. F = kx = 100×0.2 = 20 N. Using F = ma: 20 = m×50, m = 0.4 kg

A particle undergoes circular motion with radius 2 m and completes one revolution in 4 seconds. What is its centripetal acceleration?

The correct answer is A: π² m/s². Angular velocity ω = 2π/4 = π/2 rad/s. Centripetal acceleration = ω²r = (π/2)² × 2 = π² m/s²

The maximum possible efficiency of a heat engine operating between 400 K and 500 K is:

The correct answer is B: 20%. Maximum efficiency is Carnot efficiency: η_max = 1 - T_c/T_h = 1 - (400/500) = 1 - 0.8 = 0.2 = 20%.

A monatomic ideal gas undergoes an isochoric process where its pressure increases from 1 atm to 3 atm. If initial temperature is 300 K, what is the heat absorbed per mole? (R = 8.314 J/(mol·K))

The correct answer is C: 3741 J/mol. Isochoric: T₂/T₁ = P₂/P₁ = 3, so T₂ = 900 K. For monatomic gas: Cv = (3/2)R. Q = nCvΔT = 1 × (3/2) × 8.314 × 600 = 7482 J for 1 mole... Recalculating: Q = (3/2) × 8.314 × 600 = 7482 J. Let me check options again. Actually for this calculation: (3/2) × 8.314 × (900-300) = (3/2) × 8.314 × 600 = 7482 J

A railway engine of mass 10 tonnes pulls three coaches of mass 5 tonnes each on a horizontal track. The driving force is 50000 N and resistance per tonne is 500 N. What is the acceleration of the train?

The correct answer is B: 2.5 m/s². Total mass = 10 + 5 + 5 + 5 = 25 tonnes = 25000 kg. Total resistance = 25 × 500 = 12500 N. Net force = 50000 - 12500 = 37500 N. Acceleration = 37500/25000 = 1.5 m/s². Wait, let me recalculate: 37500/25000 = 1.5. But option says 2.5. Let me check: If driving force is applied to engine only and resist

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NEET Physics

Physics questions for NEET UG — Mechanics, Thermodynamics, Optics, Modern Physics.

72 Q 3 Topics Take Mock Test

Difficulty: All Easy Medium Hard 41–50 of 72

Topics in NEET Physics

All Mechanics & Laws of Motion 100 Thermodynamics 100 Optics 1

Q.41 Easy Mechanics & Laws of Motion

A body of mass 5 kg is moving with a velocity of 10 m/s. What force is required to stop it in 2 seconds?

A 25 N

B 50 N

C 75 N

D 100 N

Correct Answer: A. 25 N

EXPLANATION

Using F = ma, where a = (v-u)/t = (0-10)/2 = -5 m/s². Therefore F = 5 × 5 = 25 N

Test

Q.42 Easy Mechanics & Laws of Motion

An object is thrown vertically upward with initial velocity 20 m/s. At what time does it reach maximum height? (g = 10 m/s²)

A 1 s

B 2 s

C 3 s

D 4 s

Correct Answer: B. 2 s

EXPLANATION

At maximum height, v = 0. Using v = u - gt, 0 = 20 - 10t, therefore t = 2 s

Test

Q.43 Easy Mechanics & Laws of Motion

A car of mass 1000 kg experiences friction of 2000 N while moving. If the engine provides 5000 N of force, what is the net acceleration?

A 2 m/s²

B 3 m/s²

C 4 m/s²

D 5 m/s²

Correct Answer: B. 3 m/s²

EXPLANATION

Net force = 5000 - 2000 = 3000 N. Using F = ma, a = 3000/1000 = 3 m/s²

Test

Q.44 Easy Mechanics & Laws of Motion

A book rests on a table. The normal force on the book is 10 N. What is the weight of the book? (g = 10 m/s²)

A 0.5 kg

B 1 kg

C 2 kg

D Cannot be determined

Correct Answer: B. 1 kg

EXPLANATION

At rest, normal force equals weight. N = mg, 10 = m × 10, therefore m = 1 kg

Test

Q.45 Easy Mechanics & Laws of Motion

A 2 kg mass is subjected to forces of 3 N (east) and 4 N (north). What is the magnitude of acceleration?

A 1.5 m/s²

B 2.0 m/s²

C 2.5 m/s²

D 3.5 m/s²

Correct Answer: C. 2.5 m/s²

EXPLANATION

Net force = √(3² + 4²) = 5 N. Using F = ma, a = 5/2 = 2.5 m/s²

Test

Q.46 Easy Mechanics & Laws of Motion

A person pushes a box on a horizontal surface with a force of 50 N. If the box moves with constant velocity, what is the friction force?

A 0 N

B Less than 50 N

C Exactly 50 N

D Greater than 50 N

Correct Answer: C. Exactly 50 N

EXPLANATION

For constant velocity, acceleration = 0. By Newton's first law, net force = 0. Therefore, friction force must equal applied force = 50 N.

Test

Q.47 Easy Mechanics & Laws of Motion

Which of the following is NOT an inertial reference frame?

A A train moving at constant velocity

B A freely falling elevator

C A merry-go-round rotating at constant angular velocity

D A spaceship moving with constant velocity in space

Correct Answer: C. A merry-go-round rotating at constant angular velocity

EXPLANATION

An inertial frame has zero acceleration. A rotating frame undergoes centripetal acceleration, making it non-inertial. All others have constant velocity (zero acceleration).

Test

Q.48 Easy Mechanics & Laws of Motion

A train accelerates uniformly from rest. If it covers 100 m in the first 10 seconds, what is its acceleration?

A 1 m/s²

B 2 m/s²

C 4 m/s²

D 5 m/s²

Correct Answer: B. 2 m/s²

EXPLANATION

Using s = ut + ½at², where u = 0, s = 100 m, t = 10 s. Therefore, 100 = 0 + ½a(100), giving a = 2 m/s²

Test

Q.49 Easy Mechanics & Laws of Motion

A particle of mass 2 kg moving with velocity 10 m/s is acted upon by a constant force in the direction of motion for 5 seconds. If the final velocity is 20 m/s, the magnitude of force is:

A 2 N

B 4 N

C 5 N

D 10 N

Correct Answer: B. 4 N

EXPLANATION

Using v = u + at: 20 = 10 + a(5), a = 2 m/s². F = ma = 2×2 = 4 N

Test

Q.50 Easy Mechanics & Laws of Motion

A car moving at 20 m/s comes to rest in 5 seconds with uniform deceleration. The deceleration is:

A 2 m/s²

B 4 m/s²

C 5 m/s²

D 10 m/s²

Correct Answer: B. 4 m/s²

EXPLANATION

Using v = u + at: 0 = 20 + a(5), a = -4 m/s². Deceleration = 4 m/s²

Test

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