A wedge of mass M with angle θ is on a frictionless horizontal surface. A block of mass m is placed on the wedge. The acceleration of the wedge is: (neglecting friction between block and wedge)

The correct answer is C: mg sinθ cosθ/(M+m sin²θ). This is a complex problem requiring analysis of relative acceleration. The normal force between block and wedge creates horizontal component that accelerates the wedge. Using constraint that block accelerates with wedge horizontally and down the slope: a = mg sinθ cosθ/(M + m sin²θ)

Two forces of 12 N and 5 N act on a body. The maximum resultant force possible is:

The correct answer is B: 17 N. Maximum resultant occurs when forces act in the same direction: R = 12 + 5 = 17 N

Which statement about entropy is correct for an isolated system?

The correct answer is B: Entropy always increases or remains constant. Second law of thermodynamics: For an isolated system, ΔS ≥ 0 (entropy increases for irreversible processes, constant for reversible).

The heat capacity at constant pressure (Cp) for an ideal gas is greater than at constant volume (Cv) because:

The correct answer is B: At constant pressure, work is done by the gas. At constant P, heat goes into both increasing internal energy and doing work: Q_p = ΔU + W. At constant V, heat only increases internal energy: Q_v = ΔU. Thus Cp > Cv by R.

A reversible heat engine operates between two reservoirs at temperatures T₁ = 400 K and T₂ = 300 K. What is the maximum possible efficiency of this engine?

The correct answer is A: 25%. Maximum efficiency = 1 - (T₂/T₁) = 1 - (300/400) = 1 - 0.75 = 0.25 = 25%

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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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