Home › Subjects › JEE Physics

JEE Physics

Physics questions for JEE Main — Mechanics, Electrostatics, Optics, Modern Physics.

434 Q 9 Topics Take Test

Difficulty: All Easy Medium Hard 411–420 of 434

Topics in JEE Physics

All Mechanics 100 Thermodynamics 100 Electrostatics 100 Current Electricity 100 Magnetism 100 Optics 100 Modern Physics 100 Semiconductors 100 Waves 100

Q.411 Medium Mechanics

Two identical springs with spring constant k are connected in series. The effective spring constant is:

A 2k

B k/2

C k

D 4k

Correct Answer: B. k/2

EXPLANATION

For springs in series: 1/k_eff = 1/k + 1/k = 2/k, so k_eff = k/2

Test

Q.412 Medium Mechanics

A particle moves in a vertical circle of radius r. At the highest point, the minimum speed needed to maintain contact is:

A √(gr)

B √(2gr)

C 2√(gr)

D √(gr/2)

Correct Answer: A. √(gr)

EXPLANATION

At highest point, for minimum speed, N = 0. mg = mv²/r, so v = √(gr)

Test

Q.413 Medium Mechanics

A body experiences two perpendicular forces of 3 N and 4 N. The resultant acceleration is 2 m/s². The mass is:

A 1.5 kg

B 2 kg

C 2.5 kg

D 3.5 kg

Correct Answer: C. 2.5 kg

EXPLANATION

Resultant force = √(3² + 4²) = √25 = 5 N. Mass = F/a = 5/2 = 2.5 kg

Test

Q.414 Medium Mechanics

A uniform rod of length L is suspended vertically from one end. Its center of mass falls from height L/2 to height 0 when released. The velocity of COM when it reaches bottom is:

A √(gL/2)

B √(gL)

C √(2gL)

D √(gL/4)

Correct Answer: A. √(gL/2)

EXPLANATION

For rotating rod, energy: mg(L/2) = (1/2)Iω² + (1/2)mv². With I = mL²/3 about pivot, v_cm = √(gL/2)

Test

Q.415 Medium Mechanics

Two blocks A (2 kg) and B (3 kg) are connected by a string on a frictionless surface. A 10 N force pulls the system. The tension in the string between A and B is:

A 4 N

B 6 N

C 8 N

D 10 N

Correct Answer: B. 6 N

EXPLANATION

Total acceleration = F/(m₁+m₂) = 10/5 = 2 m/s². Tension = F - m₁a = 10 - 2×2 = 6 N (or T = m₂a = 3×2 = 6 N)

Test

Q.416 Medium Mechanics

A 2 kg block slides down a 30° incline with initial velocity 5 m/s. If friction coefficient is 0.1, what is acceleration? (g = 10 m/s²)

A 3.6 m/s²

B 4.3 m/s²

C 5.1 m/s²

D 6.2 m/s²

Correct Answer: B. 4.3 m/s²

EXPLANATION

a = g(sinθ - μcosθ) = 10(sin30° - 0.1×cos30°) = 10(0.5 - 0.1×0.866) = 10(0.5 - 0.0866) = 4.134 ≈ 4.3 m/s²

Test

Q.417 Medium Mechanics

A ball is thrown from ground with initial velocity components: vₓ = 20 m/s and vᵧ = 30 m/s. At maximum height, what is its velocity?

A 20 m/s

B 30 m/s

C 25 m/s

D 40 m/s

Correct Answer: A. 20 m/s

EXPLANATION

At maximum height, vertical component vᵧ = 0. Horizontal component vₓ remains 20 m/s. Total velocity = 20 m/s

Test

Q.418 Medium Mechanics

A satellite orbits Earth at radius r with velocity v. If radius is doubled, what is new orbital velocity?

A v

B v/√2

C v√2

D 2v

Correct Answer: B. v/√2

EXPLANATION

Orbital velocity v = √(GM/r). If r → 2r, then v' = √(GM/2r) = v/√2

Test

Q.419 Medium Mechanics

A particle in circular motion has angular velocity ω = 2t rad/s. If radius is 5 m, what is tangential acceleration at t = 2s?

A 5 m/s²

B 10 m/s²

C 15 m/s²

D 20 m/s²

Correct Answer: B. 10 m/s²

EXPLANATION

Tangential acceleration at = r(dω/dt) = 5 × 2 = 10 m/s² (constant as dω/dt = 2)

Test

Q.420 Medium Mechanics

Two objects of mass 4 kg and 6 kg move towards each other with velocities 5 m/s and 3 m/s respectively. After perfectly inelastic collision, what is their common velocity?

A 0.2 m/s

B 0.4 m/s

C 0.6 m/s

D 0.8 m/s

Correct Answer: A. 0.2 m/s

EXPLANATION

By momentum conservation: 4(5) - 6(3) = (4+6)v → 20 - 18 = 10v → v = 0.2 m/s

Test

1…40 41 42 43 44

All Subjects & Topics

Govt. Exams

Entrance Exams

Teacher Exams

Subjects

Quick Links

JEE Physics