NEET Physics · Flashcards
This deck has 15 flashcards on System of Particles - Kinematics for NEET Physics, from NCERT Class 11. It follows the NCERT chapter System of Particles and Rotational Motion.
A visual and concept-driven flashcard deck mastering Center of Mass, Torque, Angular Momentum, and Rolling Mechanics for NEET Physics.
The first 8 cards are below with their answers. Sign up free to study all 15 cards with spaced repetition.
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Card 1 of 15
State the Law of Conservation of Angular Momentum.
Hint: Example: A diver tucking their body in reduces I, which increases ω to keep L constant.
Answer
If the net external torque acting on a system is zero (τₑₓₜ = 0), the total angular momentum of the system remains constant (L = constant, or I₁ω₁ = I₂ω₂).
Card 2 of 15
What is Moment of Inertia (I)?
Hint: It depends on mass, the shape/size of the body, and the distribution of mass about the axis of rotation.
Answer
It is the property of a body by virtue of which it resists a change in its state of rest or rotational motion. I = Σ mr²
Card 3 of 15
Define Radius of Gyration (k).
Hint: It changes if you change the axis of rotation.
Answer
The perpendicular distance from the axis of rotation at which the whole mass of the body could be concentrated to give the same moment of inertia. I = Mk² or k = √(I/M)
Card 4 of 15
What is the formula for the Center of Mass (CoM) of a two-particle system?
Hint: The CoM always lies closer to the heavier mass.
Answer
R = (m₁r₁ + m₂r₂) / (m₁ + m₂)
Card 5 of 15
How does the Center of Mass move if the net external force on the system is zero?
Hint: Think of an exploding bomb in mid-air: the CoM of the fragments continues on the original parabolic path.
Answer
The Center of Mass moves with a constant velocity (acceleration of CoM is zero). Internal forces cannot change the motion of the CoM.
Card 6 of 15
Define Torque (τ) and give its mathematical formula.
Hint: Unit is Newton-meter (N·m).
Answer
Torque is the rotational analogue of force (turning effect). τ = r × F Magnitude: τ = rF sin(θ)
Card 7 of 15
Define Angular Momentum (L) and its relation to Linear Momentum (p).
Hint: For a rigid body rotating about a fixed axis, L = Iω.
Answer
Angular momentum is the moment of linear momentum. L = r × p Magnitude: L = rp sin(θ) = mvr sin(θ)
Card 8 of 15
What is the relationship between Torque and Angular Momentum?
Hint: This is Newton's Second Law for rotational motion (analogous to F = dp/dt).
Answer
The net external torque acting on a system is equal to the rate of change of its angular momentum. τₑₓₜ = dL/dt
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