System of Particles and Rotational Motion JEE Questions, Download PDF

System of Particles and Rotational Motion JEE Questions are extremely useful for building a strong foundation in mechanics. This chapter consistently appears in JEE Main and JEE Advanced, usually contributing 1-2 marks every year. Students must understand the concepts of centre of mass, torque, angular momentum, moment of inertia, and rotational dynamics to score well.

Practising System of Particles and Rotational Motion JEE Questions sharpens understanding of rotational dynamics and rigid body motion, which are frequently tested. Regular problem-solving improves accuracy, helps identify common pitfalls, and speeds up the application of formulas during exams.

System of Particles and Rotational Motion JEE Questions PDF Download

System of Particles and Rotational Motion JEE Questions PDF offers a structured collection of previous years’ problems with solutions. The PDF aids in comprehensive understanding by providing theory along with a variety of questions from basics to advanced levels. 

Practising these questions enhances problem-solving skills, clears doubts with detailed explanations, and improves scoring ability in exams.

Here are some questions from the PDF: 

Q1.  A particle of mass m is dropped from a height h above the ground. At the same time another particle of the same mass is thrown vertically upwards from the ground with a speed of sqrt(2gh). If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of sqrt(h/g) is:
(A) sqrt(1/2)
(B) sqrt(3/4)
(C) 1/2
(D) sqrt(3/2)

Q2.  Mass per unit area of a circular disc of radius a depends on the distance r from its centre as
σ(r) = A + B r.
The moment of inertia of the disc about the axis, perpendicular to the plane passing through its centre is:
[JEE Main 2020, 7 Jan (Shift 2)]
(A) 2πa^4 ( 4A/4 + B/5 )
(B) 2πa^4 ( A/4 + aB/5 )
(C) πa^4 ( 4A/4 + aB/5 )
(D) 2πa^4 ( A/4 + B/5 )

Q3. Four identical solid spheres each of mass m and radius a are placed with their centres on the four corners of a square of side b. The moment of inertia of the system about one side of square where the axis of rotation is parallel to the plane of the square is:
(A) (4/5) m a^2
(B) (8/5) m a^2 + m b^2
(C) (8/5) m a^2 + 2 m b^2
(D) (4/5) m a^2 + 2 m b^2

Q4. A system consists of two identical spheres each of mass 1.5 kg and radius 50 cm at the end of light rod. The distance between the centres of the two spheres is 5 m. What will be the moment of inertia of the system about an axis perpendicular to the rod passing through its midpoint?

For more System of Particles and Rotational motion JEE questions and answers, download the PDF from the link below: 

System of Particles and Rotational Motion JEE Questions PDF Download

Sample System of Particles and Rotational Motion JEE Questions

Here are some important system of particles and rotational motion JEE questions with solutions, similar to those commonly asked in the exam:

Q1. Two particles of masses 2 kg and 4 kg are located at (2, 0) and (6, 0). Find the centre of mass of the system.

Solution:
x_CM = (2×2 + 4×6) / (2+4)
x_CM = (4 + 24) / 6 = 28/6 = 4.66 m

Q2. A constant torque acts on a body initially at rest. If its angular acceleration is α, what is the angular displacement in time t?

Solution:
θ = (1/2) α t²

Q3. A wheel of moment of inertia 0.6 kg m² rotates at 10 rad/s. Find its rotational kinetic energy.

Solution:
K = (1/2) Iω²
K = 1/2 × 0.6 × 10² = 30 J

Q4. A force of 5 N acts at a distance of 0.2 m from a pivot. Find the torque produced.

Solution:
τ = rF
τ = 0.2 × 5 = 1 N·m

Q5. A disc rolls without slipping on a surface. What is its total kinetic energy in terms of mass m, radius R, and velocity v?

Solution:
K_total = (1/2 mv²) + (1/2 Iω²)
For disc, I = (1/2)mR² and ω = v/R
K_total = 1/2 mv² + 1/4 mv² = 3/4 mv²

Important Concepts for System of Particles and Rotational Motion JEE Questions

Below are the key concepts required to solve system of particles and rotational motion JEE questions and answers effectively:

How to Prepare Using System of Particles and Rotational Motion JEE Questions PDF?

Start by revising basic definitions and formulas like torque, COM, angular momentum, moment of inertia, and rolling motion. Here are some preparation tips: 

• Revise formulas and understand their physical meaning while solving system of particles and rotational motion JEE important questions. 
• Solve numerical and diagram-based questions daily.
• Focus on standard moment of inertia values (disc, ring, rod, sphere).
• Practice mixed conceptual and mathematical problems from the PDF.
• Solve previous year questions to understand JEE patterns.
• Attempt questions under timed conditions.
• Revisit weak areas and check detailed solutions for improvement.